“Walking into a modern building can
sometimes be compared to placing your head inside a plastic bag that
is filled with toxic fumes.”
John Bower
Founder, Healthy House Institute
Introduction
We all face a variety of risks to our health as we go about our
day-to-day lives. Driving in cars, flying in airplanes, engaging in
recreational activities, and being exposed to environmental pollutants
all pose varying degrees of risk. Some risks are simply unavoidable.
Some we choose to accept because to do otherwise would restrict our
ability to lead our lives the way we want. Some are risks we might
decide to avoid if we had the opportunity to make informed choices.
Indoor air pollution and exposure to hazardous substances in the home
are risks we can do something about.
In the last several years, a growing body of scientific evidence has
indicated that the air within homes and other buildings can be more
seriously polluted than the outdoor air in even the largest and most
industrialized cities. Other research indicates that people spend
approximately 90% of their time indoors. Thus, for many people, the
risks to health from exposure to indoor air pollution may be greater
than risks from outdoor pollution.
In addition, people exposed to indoor air pollutants for the longest
periods are often those most susceptible to their effects. Such groups
include the young, the elderly, and the chronically ill, especially
those suffering from respiratory or cardiovascular disease [1].
Indoor Air Pollution
Numerous forms of indoor air pollution are possible in the modern
home. Air pollutant levels in the home increase if not enough outdoor
air is brought in to dilute emissions from indoor sources and to carry
indoor air pollutants out of the home. In addition, high temperature
and humidity levels can increase the concentration of some pollutants.
Indoor pollutants can be placed into two groups, biologic and
chemical.
Biologic Pollutants
Biologic pollutants include bacteria, molds, viruses, animal dander,
cat saliva, dust mites, cockroaches, and pollen. These biologic
pollutants can be related to some serious health effects. Some
biologic pollutants, such as measles, chickenpox, and influenza are
transmitted through the air. However, the first two are now
preventable with vaccines. Influenza virus transmission, although
vaccines have been developed, still remains of concern in crowded
indoor conditions and can be affected by ventilation levels in the
home.
Common pollutants, such as pollen, originate from plants and can
elicit symptoms such as sneezing, watery eyes, coughing, shortness of
breath, dizziness, lethargy, fever, and digestive problems. Allergic
reactions are the result of repeated exposure and immunologic
sensitization to particular biologic allergens.
Although pollen allergies can be bothersome, asthmatic responses to
pollutants can be life threatening. Asthma is a chronic disease of the
airways that causes recurrent and distressing episodes of wheezing,
breathlessness, chest tightness, and coughing [2]. Asthma can be
broken down into two groups based on the causes of an attack:
extrinsic (allergic) and intrinsic (nonallergic). Most people with
asthma do not fall neatly into either type, but somewhere in between,
displaying characteristics of both classifications. Extrinsic asthma
has a known cause, such as allergies to dust mites, various pollens,
grass or weeds, or pet danders. Individuals with extrinsic asthma
produce an excess amount of antibodies when exposed to triggers.
Intrinsic asthma has a known cause, but the connection between the
cause and the symptoms is not clearly understood. There is no antibody
hypersensitivity in intrinsic asthma. Intrinsic asthma usually starts
in adulthood without a strong family history of asthma. Some of the
known triggers of intrinsic asthma are infections, such as cold and
flu viruses, exercise and cold air, industrial and occupational
pollutants, food additives and preservatives, drugs such as aspirin,
and emotional stress. Asthma is more common in children than in
adults, with nearly 1 of every 13 school-age children having asthma [3].
Low-income African-Americans and certain Hispanic populations suffer
disproportionately, with urban inner cities having particularly severe
problems. The impact on neighborhoods, school systems, and health care
facilities from asthma is severe because one-third of all pediatric
emergency room visits are due to asthma, and it is the fourth most
prominent cause of physician office visits. Additionally, it is the
leading cause of school absenteeism—14 million school days lost each
year—from chronic illness [4].
The U.S. population, on the average, spends as much as 90% of its time
indoors. Consequently, allergens and irritants from the indoor
environment may play a significant role in triggering asthma episodes.
A number of indoor environmental asthma triggers are biologic
pollutants. These can include rodents (discussed in
Chapter
4),
cockroaches, mites, and mold.
Cockroaches
The droppings, body parts, and saliva of cockroaches can be asthma
triggers. Cockroaches are commonly found in crowded cities and in the
southern United States. Allergens contained in the feces and saliva of
cockroaches can cause allergic reactions or trigger asthma symptoms. A
national study by Crain et al. [5] of 994
inner-city allergic children from seven U.S. cities revealed that
cockroaches were reported in 58% of the homes. The Community
Environmental Health Resource Center reports that cockroach debris,
such as body parts and old shells, trigger asthma attacks in
individuals who are sensitized to cockroach allergen [6]. Special attention to cleaning must be
a priority after eliminating the presence of cockroaches to get rid of
the presence of any allergens left that can be asthma triggers.
House Dust Mites
Another group of arthropods linked to asthma is house dust mites. In
1921, a link was suggested between asthmatic symptoms and house dust,
but it was not until 1964 that investigators suggested that a mite
could be responsible. Further investigation linked
a number of mite species to the allergen response and revealed that
humid homes have more mites and, subsequently, more allergens. In
addition, researchers established that fecal pellets deposited by the
mites accumulated in home fabrics and could become airborne via
domestic activities such as vacuuming and dusting, resulting in
inhalation by the inhabitants of the home. House dust mites are
distributed worldwide, with a minimum of 13 species identified from
house dust. The two most common in the United States are the North
American house dust mite (Dermatophagoides farinae) and the
European house dust mite (D. pteronyssinus). According to Lyon [7],
house dust mites thrive in homes that provide a source of food and
shelter and adequate humidity. Mites prefer relative humidity levels
of 70% to 80% and temperatures of 75°F to 80°F (24°C to 27°C). Most
mites are found in bedrooms in bedding, where they spend up to a third
of their lives. A typical used mattress may have from 100,000 to 10
million mites in it. In addition, carpeted floors, especially long,
loose pile carpet, provide a microhabitat for the accumulation of food
and moisture for the mite, and also provide protection from removal by
vacuuming. The house dust mite’s favorite food is human dander (skin
flakes), which are shed at a rate of approximately 0.20 ounces per
week.
A good microscope, as well as a trained observer, are imperative in
detecting mites. House dust mites also can be detected using
diagnostic tests that measure the presence and infestation level of
mites by combining dust samples collected from various places inside
the home with indicator reagents [7]. Assuming the presence of
mites, the precautions listed below should be taken if people with
asthma are present in the home:
- Use synthetic rather than feather and down pillows.
- Use an approved allergen barrier cover to enclose the top and
sides of mattresses and pillows and the base of the bed.
- Use a damp cloth to dust the plastic mattress cover daily.
- Change bedding and vacuum the bed base and mattress weekly.
- Use nylon or cotton cellulose blankets rather than wool
blankets.
- Use hot (120°F–130°F [49°C–54°C]) water to wash all bedding, as well as
room curtains.
- Eliminate or reduce fabric wall hangings, curtains, and drapes.
- Use wood, tile, linoleum, or vinyl floor covering rather than
carpet. If carpet is present, vacuum regularly with a
high-efficiency particulate air (HEPA) vacuum or a household vacuum
with a microfiltration bag.
- Purchase stuffed toys that are machine washable.
- Use fitted sheets to help reduce the accumulation of human skin
on the mattress surface.
HEPA vacuums are now widely
available and have also been shown to be effective [8]. A conventional
vacuum tends to be inefficient as a control measure and results in a
significant increase in airborne dust concentrations, but can be used
with multilayer microfiltration collection bags. Another approach to
mite control is reducing indoor humidity to below 50% and installing
central air conditioning.
Two products are available to treat house dust mites and their
allergens. These products contain the active ingredients benzyl
benzoate and tannic acid.
Pets
According to the U.S. Environmental Protection Agency (EPA) [9],
pets can be significant asthma triggers because of dead skin flakes,
urine, feces, saliva, and hair. Proteins in the dander, urine, or
saliva of warm-blooded animals can sensitize individuals and lead to
allergic reactions or trigger asthmatic episodes. Warm-blooded animals
include dogs, cats, birds, and rodents (hamsters, guinea pigs,
gerbils, rats, and mice). Numerous strategies, such as the following,
can diminish or eliminate animal allergens in the home:
- Eliminate animals from the home.
- Thoroughly clean the home (including floors and walls) after
animal removal.
- If pets must remain in the home, reduce pet exposure in sleeping
areas. Keep pets away from upholstered furniture, carpeted areas,
and stuffed toys, and keep the pets outdoors as much as possible.
However, there is some
evidence that pets introduced early into the home may prevent asthma.
Several studies have shown that exposure to dogs and cats in the first
year of life decreases a child’s chances of developing allergies [10]
and that exposure to cats significantly decreases sensitivity to
cats in adulthood [11]. Many other studies
have shown a decrease in allergies and asthma among children who grew
up on a farm and were around many animals [12].
Mold
People are routinely exposed to more than 200 species of fungi indoors
and outdoors [13]. These include moldlike fungi, as well as
other fungi such as yeasts and mushrooms. The terms “mold” and
“mildew” are nontechnical names commonly used to refer to any fungus
that is growing in the indoor environment. Mold colonies may appear
cottony, velvety, granular, or leathery, and may be white, gray,
black, brown, yellow, greenish, or other colors. Many reproduce via
the production and dispersion of spores. They usually feed on dead
organic matter and, provided with sufficient moisture, can live off of
many materials found in homes, such as wood, cellulose in the paper
backing on drywall, insulation, wallpaper, glues used to bond carpet
to its backing, and everyday dust and dirt.
Certain molds can cause a variety of adverse human health effects,
including allergic reactions and immune responses (e.g., asthma),
infectious disease (e.g., histoplasmosis), and toxic effects (e.g.,
aflatoxin-induced liver cancer from exposure to this mold-produced
toxin in food) [14]. A recent Institute of Medicine (IOM) review
of the scientific literature found sufficient evidence for an
association between exposure to mold or other agents in damp indoor
environments and the following conditions: upper respiratory tract
symptoms, cough, wheeze, hypersensitivity pneumonitis in susceptible
persons, and asthma symptoms in sensitized persons [15].
A previous scientific review was more specific in concluding that
sufficient evidence exists to support associations between fungal
allergen exposure and asthma exacerbation and upper respiratory
disease [13]. Finally, mold toxins can
cause direct lung damage leading to pulmonary diseases other than
asthma [13].
The topic of residential mold has received increasing public and media
attention over the past decade. Many news stories have focused on
problems associated with “toxic mold” or “black mold,” which is often
a reference to the toxin-producing mold, Stachybotrys chartarum. This
might give the impression that mold problems in homes are more
frequent now than in past years; however, no good evidence supports
this. Reasons for the increasing attention to this issue include
high-visibility lawsuits brought by property owners against builders
and developers, scientific controversies regarding the degree to which
specific illness outbreaks are mold-induced, and an increase in the
cost of homeowner insurance policies due to the increasing number of
mold-related claims. Modern construction might be more vulnerable to
mold problems because tighter construction makes it more difficult for
internally generated water vapor to escape, as well as the widespread
use of paper-backed drywall in construction (paper is an excellent
medium for mold growth when wet), and the widespread use of carpeting.
Allergic Health Effects. Many molds produce numerous protein or
glycoprotein allergens capable of causing allergic reactions in
people. These allergens have been measured in spores as well as in
other fungal fragments. An estimated 6%–10% of the general population
and 15%–50% of those who are genetically susceptible are sensitized to
mold allergens [13]. Fifty percent of the 937 children tested in
a large multicity asthma study sponsored by the National Institutes of
Health showed sensitivity to mold, indicating the importance of mold
as an asthma trigger among these children [16]. Molds are
thought to play a role in asthma in several ways. Molds produce many
potentially allergenic compounds, and molds may play a role in asthma
via release of irritants that increase potential for sensitization or
release of toxins (mycotoxins) that affect immune response [13].
Toxics and Irritants. Many molds also produce mycotoxins that
can be a health hazard on ingestion, dermal contact, or inhalation [14].
Although common outdoor molds present in ambient air, such as Cladosporium cladosporioides and
Alternaria alternata, do not usually produce toxins, many other
different mold species do [17].
Genera-producing fungi associated with wet buildings, such as
Aspergillus versicolor, Fusarium verticillioides, Penicillium
aiurantiorisen, and S. chartarum, can produce potent toxins [17].
A single mold species may produce several different toxins, and a
given mycotoxin may be produced by more than one species of fungi.
Furthermore, toxin-producing fungi do not necessarily produce
mycotoxins under all growth conditions, with production being
dependent on the substrate it is metabolizing, temperature, water
content, and humidity [17]. Because species
of toxin-producing molds generally have a higher water requirement
than do common household molds, they tend to thrive only under
conditions of chronic and severe water damage [18]. For example, Stachybotrys
typically only grows under continuously wet conditions [19]. It has been suggested that very young
children may be especially vulnerable to certain mycotoxins [19,20].
For example, associations have been reported for pulmonary hemorrhage
(bleeding lung) deaths in infants and the presence of S.
chartarum [21,22,23,24].
Causes of Mold. Mold growth can be caused by any condition resulting
in excess moisture. Common moisture sources include rain leaks (e.g.,
on roofs and wall joints); surface and groundwater leaks (e.g., poorly
designed or clogged rain gutters and footing drains, basement leaks);
plumbing leaks; and stagnant water in appliances (e.g., dehumidifiers,
dishwashers, refrigerator drip pans, and condensing coils and drip
pans in HVAC systems). Moisture problems can also be due to water
vapor migration and condensation problems, including uneven indoor
temperatures, poor air circulation, soil air entry into basements,
contact of humid unconditioned air with cooled interior surfaces, and
poor insulation on indoor chilled surfaces (e.g., chilled water
lines). Problems can also be caused by the production of excess
moisture within homes from humidifiers, unvented clothes dryers,
overcrowding, etc. Finished basements are particularly susceptible to
mold problems caused by the combination of poorly controlled moisture
and mold-supporting materials (e.g., carpet, paper-backed sheetrock) [15]. There is also some evidence that mold spores from damp
or wet crawl spaces can be transported through air currents into the
upper living quarters. Older, substandard housing low income families
can be particularly prone to mold problems because of inadequate
maintenance (e.g., inoperable gutters, basement and roof leaks),
overcrowding, inadequate insulation, lack of air conditioning, and
poor heating. Low interior temperatures (e.g., when one or two rooms
are left unheated) result in an increase in the relative humidity,
increasing the potential for water to condense on cold surfaces.
Mold Assessment Methods. Mold growth or the potential for mold growth
can be detected by visual inspection for active or past microbial
growth, detection of musty odors, and inspection for water staining or
damage. If it is not possible or practical to inspect a residence,
this information can be obtained using occupant questionnaires. Visual
observation of mold growth, however, is limited by the fact that
fungal elements such as spores are microscopic, and that their
presence is often not apparent until growth is extensive and the fact
that growth can occur in hidden spaces (e.g., wall cavities, air
ducts).
Portable, hand-held moisture meters, for the direct measurement of
moisture levels in materials, may also be useful in qualitative home
assessments to aid in pinpointing areas of potential biologic growth
that may not otherwise be obvious during a visual inspection [14].
For routine assessments in which the goal is to identify possible mold
contamination problems before remediation, it is usually unnecessary
to collect and analyze air or settled dust samples for mold analysis
because decisions about appropriate intervention strategies can
typically be made on the basis of a visual inspection [25].
Also, sampling and analysis costs can be relatively high and the
interpretation of results is not straightforward. Air and dust
monitoring may, however, be necessary in certain situations, including
1) if an individual has been diagnosed with a disease associated with
fungal exposure through inhalation, 2) if it is suspected that the
ventilation systems are contaminated, or 3) if the presence of mold is
suspected but cannot be identified by a visual inspection or bulk
sampling [26]. Generally, indoor environments contain large reservoirs
of mold spores in settled dust and contaminated building materials, of
which only a relatively small amount is airborne at a given time.
Common methods for sampling for mold growth include bulk sampling
techniques, air sampling, and collection of settled dust samples. In
bulk sampling, portions of materials with visual or suspected mold
growth (e.g., sections of wallboard, pieces of duct lining, carpet
segments, or return air filters) are collected and directly examined
to determine if mold is growing and to identify the mold species or
groups that are present. Surface sampling in mold contamination
investigations may also be used when a less destructive technique than
bulk sampling is desired. For example, nondestructive samples of mold
may be collected using a simple swab or adhesive tape [14].
Air can also be sampled for mold using pumps that pull air across a
filter medium, which traps airborne mold spores and fragments. It is
generally recommended that outdoor air samples are collected
concurrent with indoor samples for comparison purposes for measurement
of baseline ambient air conditions. Indoor contamination can be
indicated by indoor mold distributions (both species and
concentrations) that differ significantly from the distributions in
outdoor samples [14]. Captured mold spores can be examined under a
microscope to identify the mold species/groups and determine
concentrations or they can be cultured on growth media and the
resulting colonies counted and identified. Both techniques require
considerable expertise.
Dust sampling involves the collection of settled dust samples (e.g.,
floor dust) using a vacuum method in which the dust is collected onto
a porous filter medium or into a container. The dust is then processed
in the laboratory and the mold identified by culturing viable spores.
Mold Standards. No standard numeric guidelines exist for
assessing whether mold contamination exists in an area. In the United
States, no EPA regulations or standards exist for airborne mold
contaminants [26].
Various governmental and private organizations have, however, proposed
guidance on the interpretation of fungal measures of environmental
media in indoor environments (quantitative limits for fungal
concentrations).
Given evidence that young children may be especially vulnerable to
certain mycotoxins [18] and in view of the potential severity or
diseases associated with mycotoxin exposure, some organizations
support a precautionary approach to limiting mold exposure [19].
For example, the American Academy of Pediatrics recommends that
infants under 1 year of age are not exposed at all to chronically
moldy, water-damaged environments [18].
Mold Mitigation. Common intervention methods for addressing mold
problems include the following:
- maintaining heating, ventilating, and air conditioning (HVAC)
systems;
- changing HVAC filters frequently, as recommended by
manufacturer;
- keeping gutters and downspouts in working order and ensuring
that they drain water away from the foundation;
- routinely checking, cleaning, and drying drip pans in air
conditioners, refrigerators, and dehumidifiers;
- increasing ventilation (e.g., using exhaust fans or open windows
to remove humidity when cooking, showering, or using the
dishwasher);
- venting clothes dryers to the outside; and
- maintaining an ideal relative humidity level in the home of
40%
to 60%.
- locating and removing sources of moisture (controlling dampness
and humidity and repairing water leakage problems);
- cleaning or removing mold-contaminated materials;
- removing materials with severe mold growth; and
- using high-efficiency air filters.
Moisture Control.
Because one of the most important factors affecting mold growth in
homes is moisture level, controlling this factor is crucial in mold
abatement strategies. Many simple measures can significantly control
moisture, for example maintaining indoor relative humidity at no
greater than 40%–60% through the use of dehumidifiers, fixing water
leakage problems, increasing ventilation in kitchens and bathrooms by
using exhaust fans, venting clothes dryers to the outside, reducing
the number of indoor plants, using air conditioning at times of high
outdoor humidity, heating all rooms in the winter and adding heating
to outside wall closets, sloping surrounding soil away from building
foundations, fixing gutters and downspouts, and using a sump pump in
basements prone to flooding [27]. Vapor
barriers, sump pumps, and aboveground vents can also be installed in
crawlspaces to prevent moisture problems [28].
Removal and Cleaning of Mold-contaminated Materials. Nonporous (e.g.,
metals, glass, and hard plastics) and semiporous (e.g., wood and
concrete) materials contaminated with mold and that are still
structurally sound can often be cleaned with bleach-and-water solutions.
However, in some cases, the material may not be easily cleaned or may
be so severely contaminated that it may have to be removed. It is
recommended that porous materials (e.g., ceiling tiles, wallboards,
and fabrics) that cannot be cleaned be removed and discarded [29].
In severe cases, clean-up and repair of mold-contaminated buildings
may be conducted using methods similar to those used for abatement of
other hazardous substances such as asbestos [30]. For example, in
situations of extensive colonization (large surface areas greater than
100 square feet or where the material is severely
degraded), extreme precautions may be required, including full
containment (complete isolation of work area) with critical barriers
(airlock and decontamination room) and negative pressurization,
personnel trained to handle hazardous wastes, and the use of full-face
respirators with HEPA filters, eye protection, and disposable
full-body covering [26].
Worker Protection When Conducting Mold Assessment and Mitigation
Projects. Activities such as cleaning or removal of
mold-contaminated materials in homes, as well as investigations of
mold contamination extent, have the potential to disturb areas of mold
growth and release fungal spores and fragments into the air.
Recommended measures to protect workers during mold remediation
efforts depend on the severity and nature of the mold contamination
being addressed, but include the use of well fitted particulate masks
or respirators that retain particles as small as 1 micrometer or less,
disposable gloves and coveralls, and protective eyewear [31].
Following are examples of guidance documents for remediation of mold
contamination:
New York City Department of Health and Mental Hygiene Guidelines
on Assessment and
Remediation of Fungi in Indoor Environments (available from URL:
http://www.nyc.gov/html/doh/html/epi/moldrpt1.shtml).
American Conference of Governmental Industrial Hygienists (ACGIH) 1999
document, Biosaerosols: Assessment and Control (can be ordered at URL
http://www.acgih.org/home.htm).
American Industrial Hygiene Association (AIHA) 2004 document,
Assessment, Remediation, and Post-Remediation Verification of Mold in
Buildings (can be ordered at URL
www.aiha.org)
Environmental Protection Agency guidance, Mold Remediation in Schools
and Commercial Buildings (includes many general principles also
applicable to residential mold mitigation efforts; available at URL:
http://www.epa.gov/iaq/molds/mold_remediation.html)
Environmental Protection Agency guidance, A Brief Guide to Mold,
Moisture, and Your Home (for homeowners and renters on how to clean up
residential mold problems and how to prevent mold growth; available at
URL:
http://www.epa.gov/iaq/molds/images/moldguide.pdf)
Figure 5.1 shows mold growth in the home.
Chemical Pollutants
Carbon Monoxide
Carbon monoxide (CO) is a significant combustion pollutant in the
United States. CO is a leading cause of poisoning deaths [32].
According to the National Fire Protection Association (NFPA),
CO-related nonfire deaths are often attributed to heating and cooking
equipment. The leading specific types of equipment blamed for
CO-related deaths include gas-fueled space heaters, gas-fueled
furnaces, charcoal grills, gas-fueled ranges, portable kerosene
heaters, and wood stoves.
As with fire deaths, the risk for unintentional CO death is highest
for the very young (ages 4 years and younger) and the very old (ages
75 years and older). CO is an odorless, colorless gas that can cause
sudden illness and death. It is a result of the incomplete combustion
of carbon. Headache, dizziness, weakness, nausea, vomiting, chest
pain, and confusion are the most frequent symptoms of CO poisoning.
According to the American Lung Association (ALA) [33], breathing low
levels of CO can cause fatigue and increase chest pain in people with
chronic heart disease. Higher levels of CO can cause flulike symptoms
in healthy people. In addition, extremely high levels of CO cause loss
of consciousness and death. In the home, any fuel-burning appliance
that is not adequately vented and maintained can be a potential source
of CO. The following steps should be followed to reduce CO (as well as
sulfur dioxide and oxides of nitrogen) levels:
- Never use gas-powered equipment, charcoal grills, hibachis,
lanterns, or portable camping stoves in enclosed areas or indoors.
- Install a CO monitor (Figure
5.2) in appropriate areas of the
home. These monitors are designed to provide a warning before
potentially life-threatening levels of CO are reached.
- Choose vented appliances when possible and keep gas appliances
properly adjusted to decrease the combustion to CO. (Note: Vented
appliances are always preferable for several reasons: oxygen levels,
carbon dioxide buildup, and humidity management).
- Only buy certified and tested combustion appliances that meet
current safety standards, as certified by Underwriter’s Laboratories
(UL), American Gas Association (AGA) Laboratories, or equivalent.
- Assure that all gas heaters possess safety devices that shut off
an improperly vented gas heater. Heaters made after 1982 use a pilot
light safety system known as an oxygen depletion sensor. When
inadequate fresh air exists, this system shuts off the heater before
large amounts of CO can be produced.
- Use appliances that have electronic ignitions instead of pilot
lights. These appliances are typically more energy efficient and
eliminate the continuous low-level pollutants from pilot lights.
- Use the proper fuel in kerosene appliances.
- Install and use an exhaust fan vented to the outdoors over gas
stoves.
- Have a trained professional annually inspect, clean, and tune up
central heating systems (furnaces, flues, and chimneys) and repair
them as needed.
- Do not idle a car inside a garage.
The U.S. Consumer Product
Safety Commission (CPSC) recommends installing at least one CO alarm
per household near the sleeping area. For an extra measure of safety,
another alarm should be placed near the home’s heating source. ALA
recommends weighing the benefits of using models powered by electrical
outlets versus models powered by batteries that run out of power and
need replacing. Battery-powered CO detectors provide continuous
protection and do not require recalibration in the event of a power
outage. Electric-powered systems do not provide protection during a
loss of power and can take up to 2 days to recalibrate. A device that
can be easily self-tested and reset to ensure proper functioning
should be chosen. The product should meet Underwriters Laboratories
Standard UL 2034.
Ozone
Inhaling ozone can damage the lungs. Inhaling small amounts of ozone
can result in chest pain, coughing, shortness of breath, and throat
irritation. Ozone can also exacerbate chronic respiratory diseases
such as asthma. Susceptibility to the effects of ozone varies from
person to person, but even healthy people can experience respiratory
difficulties from exposure.
According to the North Carolina Department of Health and Human
Services [34], the major source of indoor ozone is outdoor ozone.
Indoor levels can vary from 10% of the outdoor air to levels as high
as 80% of the outdoor air. The Food and Drug Administration has set a
limit of 0.05 ppm of ozone in indoor air. In recent years, there have
been numerous advertisements for ion generators that destroy harmful
indoor air pollutants. These devices create ozone or elemental oxygen
that reacts with pollutants. EPA has reviewed the evidence on ozone
generators and states: “available scientific evidence shows that at
concentrations that do not exceed public health standards, ozone has
little potential to remove indoor air contaminants,” and “there is
evidence to show that at concentrations that do not exceed public
health standards, ozone is not effective at removing many odor causing
chemicals” [35].
Ozone is also created by the exposure of polluted air to sunlight or
ultraviolet light emitters. This ozone produced outside of the home
can infiltrate the house and react with indoor surfaces, creating
additional pollutants.
Environmental Tobacco Smoke or Secondhand Smoke
Like CO, environmental tobacco smoke (ETS), also known as “secondhand smoke,”
like CO, is a product of combustion. The National Cancer Institute
(NCI) [36], states that ETS is the combination of two forms of smoke
from burning tobacco products:
- Sidestream smoke, or smoke that is emitted between the puffs of
a burning cigarette, pipe, or cigar; and
- Mainstream smoke, or the smoke that is exhaled by the smoker.
The physiologic effects of
ETS are numerous. ETS can trigger asthma; irritate the eyes, nose, and
throat; and cause ear infections in children, respiratory illnesses,
and lung cancer. ETS is believed to cause asthma by irritating
chronically inflamed bronchial passages. According to the EPA [37],
ETS
is a Group A carcinogen; thus, it is a known cause of cancer in
humans. Laboratory analysis has revealed that ETS contains in excess
of 4,000 substances, more than 60 of which cause cancer in humans or
animals. The EPA also estimates that approximately 3,000 lung cancer
deaths occur each year in nonsmokers due to ETS. Additionally, passive
smoking can lead to coughing, excess phlegm, and chest discomfort. NCI
also notes that spontaneous abortion (miscarriage), cervical cancer,
sudden infant death syndrome, low birth weight, nasal sinus cancer,
decreased lung function, exacerbation of cystic fibrosis, and negative
cognitive and behavioral effects in children have been linked to ETS [36].
The EPA [37] states that, because of their relative body size and
respiratory rates, children are affected by ETS more than adults are.
It is estimated that an additional 7,500 to 15,000 hospitalizations
resulting from increased respiratory infections occur in children
younger than 18 months of age due to ETS exposure.
Figure 5.3 shows
the ETS exposure levels in homes with children under age 7 years. The
following actions are recommended in the home to protect children from
ETS:
- if individuals insist on smoking, increase ventilation in the
smoking area by opening windows or using exhaust fans; and
- refrain from smoking in the presence of children and do not
allow babysitters or others who work in the home to smoke in the
home or near children.
Volatile Organic Compounds
In the modern home, many organic chemicals are used as ingredients in
household products. Organic chemicals that vaporize and become gases
at normal room temperature are collectively known as VOCs.
Examples of common items that can release VOCs include paints,
varnishes, and wax, as well as in many cleaning, disinfecting,
cosmetic, degreasing, and hobby products. Levels of approximately a
dozen common VOCs can be two to five times higher inside the home, as
opposed to outside, whether in highly industrialized areas or rural
areas. VOCs that frequently pollute indoor air include toluene,
styrene, xylenes, and trichloroethylene. Some of these chemicals may
be emitted from aerosol products, dry-cleaned clothing, paints,
varnishes, glues, art supplies, cleaners, spot removers, floor waxes,
polishes, and air fresheners. The health effects of these chemicals
are varied. Trichlorethylene has been linked to childhood leukemia.
Exposure to toluene can put pregnant women at risk for having babies
with neurologic problems, retarded growth, and developmental problems.
Xylenes have been linked to birth defects. Styrene is a suspected
endocrine disruptor, a chemical that can block or mimic hormones in
humans or animals. EPA data reveal that methylene chloride, a common
component of some paint strippers, adhesive removers, and specialized
aerosol spray paints, causes cancer in animals [38]. Methylene chloride
is also converted to CO in the body and can cause symptoms associated
with CO exposure. Benzene, a known human carcinogen, is contained in
tobacco smoke, stored fuels, and paint supplies. Perchloroethylene, a
product uncommonly found in homes, but common to dry cleaners, can be
a pollution source by off-gassing from newly cleaned clothing.
Environmental Media Services [39] also notes that xylene, ketones, and
aldehydes are used in aerosol products and air fresheners.
To lower levels of VOCs in the home, follow these steps:
- use all household products according to directions;
- provide good ventilation when using these products;
- properly dispose of partially full containers of old or unneeded
chemicals;
- purchase limited quantities of products; and
- minimize exposure to emissions from products containing
methylene chloride, benzene, and perchlorethylene.
A prominent VOC found in
household products and construction products is formaldehyde.
According to CPSC [40], these products include the glue or adhesive
used in pressed wood products; preservatives in paints, coating, and
cosmetics; coatings used for permanent-press quality in fabrics and
draperies; and the finish on paper products and certain insulation
materials. Formaldehyde is contained in urea-formaldehyde (UF) foam
insulation installed in the wall cavities of homes as an energy
conservation measure. Levels of formaldehyde increase soon after
installation of this product, but these levels decline with time. In
1982, CPSC voted to ban UF foam insulation. The courts overturned the
ban; however, the publicity has decreased the use of this product.
More recently, the most significant source of formaldehyde in homes
has been pressed wood products made using adhesives that contain UF
resins [41]. The most significant of these is medium-density
fiberboard, which contains a higher resin-to-wood ratio than any other UF pressed wood product. This product is generally recognized as being
the highest formaldehyde-emitting pressed wood product. Additional
pressed wood products are produced using phenol-formaldehyde resin.
The latter type of resin generally emits formaldehyde at a
considerably slower rate than those containing UF resin. The emission
rate for both resins will change over time and will be influenced by
high indoor temperatures and humidity. Since 1985, U.S. Department of
Housing and Urban Development (HUD) regulations (24 CFR 3280.308,
3280.309, and 3280.406) have permitted only the use of plywood and
particleboard that conform to specified formaldehyde emission limits
in the construction of prefabricated and manufactured homes [42]. This
limit was to ensure that indoor formaldehyde levels are below 0.4 ppm.
CPSC [40] notes that formaldehyde is a colorless, strong-smelling gas.
At an air level above 0.1 ppm, it can cause watery eyes; burning
sensations in the eyes, nose, and throat; nausea; coughing; chest
tightness; wheezing; skin rashes; and allergic reactions. Laboratory
animal studies have revealed that formaldehyde can cause cancer in
animals and may cause cancer in humans. Formaldehyde is usually
present at levels less than 0.03 ppm indoors and outdoors, with rural
areas generally experiencing lower concentrations than urban areas.
Indoor areas that contain products that release formaldehyde can have
levels greater than 0.03 ppm. CPSC also recommends the following
actions to avoid high levels of exposure to formaldehyde:
- Purchase pressed wood products that are labeled or stamped to be
in conformance with American National Standards Institute criteria
ANSI A208.1-1993. Use particleboard flooring marked with ANSI grades
PBU, D2, or D3. Medium-density fiberboard should be in conformance
with ANSI A208.2-1994 and hardwood plywood with ANSI/HPVA HP-1-1994
(Figure 5.4).
- Purchase furniture or cabinets that contain a high percentage of
panel surface and edges that are laminated or coated. Unlaminated or
uncoated (raw) panels of pressed wood panel products will generally
emit more formaldehyde than those that are laminated or coated.
- Use alternative products, such as wood panel products not made
with UF glues, lumber, or metal.
- Avoid the use of foamed-in-place insulation containing
formaldehyde, especially UF foam insulation.
- Wash durable-press fabrics before use.
CPSC also recommends the following actions to reduce existing
levels of indoor formaldehyde:
- Ventilate the home well by opening doors and windows and
installing an exhaust fan(s).
- Seal the surfaces of formaldehyde-containing products that are
not laminated or coated with paint, varnish, or a layer of vinyl or
polyurethane-like materials.
- Remove products that release formaldehyde in the indoor air from
the home.
Radon
According to the EPA [43], radon is a colorless, odorless gas that
occurs naturally in soil and rock and is a decay product of uranium.
The U.S. Geological Survey (USGS) [44] notes that the typical uranium
content of rock and the surrounding soil is between 1 and 3 ppm.
Higher levels of uranium are often contained in rock such as
light-colored volcanic rock, granite, dark shale, and sedimentary rock
containing phosphate. Uranium levels as high as 100 ppm may be present
in various areas of the United States because of these rocks. The main
source of high-level radon pollution in buildings is surrounding
uranium-containing soil. Thus, the greater the level of uranium
nearby, the greater the chances are that buildings in the area will
have high levels of indoor radon.
Figure 5.5 demonstrates the
geographic variation in radon levels in the United States. Maps of the
individual states and areas that have proven high for radon are
available at
http://www.epa.gov/iaq/radon/zonemap.html. A free video
is available from the U.S. EPA: call 1-800-438-4318 and ask for EPA
402-V-02-003 (TRT 13.10).
Radon, according to the California Geological Survey [45], is one of
the intermediate radioactive elements formed during the radioactive
decay of uranium-238, uranium-235, or thorium-232. Radon-222 is the
radon isotope of most concern to public health because of its longer
half-life (3.8 days). The mobility of radon gas is much greater than
are uranium and radium, which are solids at room temperature. Thus,
radon can leave rocks and soil, move through fractures and pore
spaces, and ultimately enter a building to collect in high
concentrations. When in water, radon moves less than 1 inch before it decays, compared to 6 feet or
more in dry rocks or soil. USGS [44] notes that radon near the surface
of soil typically escapes into the atmosphere. However, where a house
is present, soil air often flows toward the house foundation because
of
- differences in air pressure between the soil and the house, with
soil pressure often being higher;
- presence of openings in the house’s foundation; and
- increases in permeability around the basement (if present).
Houses are often constructed
with loose fill under a basement slab and between the walls and
exterior ground. This fill is more permeable than the original ground.
Houses typically draw less than 1% of their indoor air from the soil.
However, houses with low indoor air pressures, poorly sealed
foundations, and several entry points for soil air may draw up to 20%
of their indoor air from the soil.
USGS [44] states that radon may also enter the home through the water
systems. Surface water sources typically contain little radon because
it escapes into the air. In larger cities, radon is released to the
air by municipal processing systems that aerate the water. However, in
areas where groundwater is the main water supply for communities,
small public systems and private wells are typically closed systems
that do not allow radon to escape. Radon then enters the indoor air
from showers, clothes washing, dishwashing, and other uses of water.
Figure 5.6 shows typical entry points of radon.
Health risks of radon stem from its breakdown into “radon daughters,”
which emit high-energy alpha particles. These progeny enter the lungs,
attach themselves, and may eventually lead to lung cancer. This
exposure to radon is believed to contribute to between 15,000 and
21,000 excess lung cancer deaths in the United States each year. The
EPA has identified levels greater than 4 picocuries per liter as
levels at which remedial action should be taken. Approximately 1 in 15
homes nationwide have radon above this level, according to the U.S.
Surgeon General’s recent advisory [46]. Smokers are at significantly
higher risk for radon-related lung cancer.
Radon in the home can be measured either by the occupant or by a
professional. Because radon has no odor or color, special devices are
used to measure its presence. Radon levels vary from day to day and
season to season. Short-term tests (2 to 90 days) are best if quick
results are needed, but long-term tests (more than 3 months) yield
better information on average year-round exposure. Measurement devices
are routinely placed in the lowest occupied level of the home. The
devices either measure the radon gas directly or the daughter
products. The simplest devices are passive, require no electricity,
and include a charcoal canister, charcoal liquid scintillation device,
alpha tract detector, and electret ion detectors [47].
All of these devices, with the exception of the ion detector, can be
purchased in hardware stores or by mail. The ion detector generally is
only available through laboratories. These devices are inexpensive,
primarily used for short-term testing, and require little to no
training. Active devices, however, need electrical power and include
continuous monitoring devices. They are customarily more expensive and
require professionally trained testers for their operation.
Figure 5.7
shows examples of the charcoal tester (a; left) and the alpha tract
detector (b; right).
After testing and evaluation by a professional, it may be necessary to
lower the radon levels in the structure. The Pennsylvania Department
of Environmental Protection [48] states that in most cases, a system
with pipes and a fan is used to reduce radon. This system, known as a subslab depressurization system, requires no major changes to the
home. The cost typically ranges from $500 to $2,500 and averages
approximately $1,000, varying with geographic region. The typical
mitigation system usually has only one pipe penetrating through the
basement floor; the pipe also may be installed outside the house.
The Connecticut Department of Public Health [49]
notes that it is more
cost effective to include radon-resistant techniques while
constructing a building than to install a reduction system in an existing
home. Inclusion of radon-resistant techniques in initial construction
costs approximately $350 to $500 [50].
Figure 5.8 shows examples of
radon-resistant construction techniques.
A passive radon-resistant system has five major parts:
- A layer of gas-permeable material under the foundation
- The foundation (usually 4 inches of gravel)
- Plastic sheeting over the foundation, with all openings in the
concrete foundation floor sealed and caulked
- A gas-tight, 3- or 4 inch vent pipe running
from under the foundation through the house to the roof
- A roughed-in electrical junction box for the future installation
of a fan, if needed.
These features create a physical barrier to radon entry. The vent pipe
redirects the flow of air under the foundation, preventing radon from
seeping into the house.
Pesticides
Much pesticide use could be reduced if integrated pest management (IPM)
practices were used in the home. IPM is a coordinated approach to
managing roaches, rodents, mosquitoes, and other pests that integrates
inspection, monitoring, treatment, and evaluation, with special
emphasis on the decreased use of toxic agents. However, all pest
management options, including natural, biologic, cultural, and
chemical methods, should be considered. Those that have the least
impact on health and the environment should be selected. Most
household pests can be controlled by eliminating the habitat for the
pest both inside and outside, building or screening them out,
eliminating food and harborage areas, and safely using appropriate
pesticides if necessary.
EPA [51] states that 75% of U.S. households used at least one pesticide
indoors during the past year and that 80% of most people’s exposure to
pesticides occurs indoors. Measurable levels of up to a dozen
pesticides have been found in the air inside homes. Pesticides used in
and around the home include products to control insects
(insecticides), termites (termiticides), rodents (rodenticides), fungi
(fungicides), and microbes (disinfectants). These products are found
in sprays, sticks, powders, crystals, balls, and foggers.
Delaplane [52] notes that the ancient Romans killed insect pests by
burning sulfur and controlled weeds with salt. In the 1600s, ants were
controlled with mixtures of honey and arsenic. U.S. farmers in the
late 19th century used copper actoarsenite (Paris green), calcium
arsenate, nicotine sulfate, and sulfur to control insect pests in
field crops. By World War II and afterward, numerous pesticides had
been introduced, including DDT, BHC, aldrin, dieldrin, endrin, and
2,4-D. A significant factor with regard to these pesticides used in
and around the home is their impact on children. According to a 2003
EPA survey, 47% of all households with children under the age of 5
years had at least one pesticide stored in an unlocked cabinet less
than 4 feet off the ground. This is within easy reach of
children. Similarly, 74% of households without children under the age
of 5 also stored pesticides in an unlocked cabinet less than 4 feet
off the ground. This issue is significant because 13% of
all pesticide poisoning incidents occur in homes other than the
child’s home. The EPA [53] notes a report by the American Association
of Poison Control Centers indicating that approximately 79,000
children were involved in common household pesticide poisonings or
exposures.
The health effects of pesticides vary with the product. However, local
effects from most of the products will be on eyes, noses, and throats;
more severe consequences, such as on the central nervous system and
kidneys and on cancer risks, are possible. The active and inert
ingredients of pesticides can be organic compounds, which can
contribute to the level of organic compounds in indoor air. More
significantly, products containing cyclodiene pesticides have been
commonly associated with misapplication. Individuals inadvertently
exposed during this misapplication had numerous symptoms, including
headaches, dizziness, muscle twitching, weakness, tingling sensations,
and nausea. In addition, there is concern that these pesticides may
cause long-term damage to the liver and the central nervous system, as
well as an increased cancer risk. Cyclodiene pesticides were developed
for use as insecticides in the 1940s and 1950s. The four main
cyclodiene pesticides—aldrin, dieldrin, chlordane, and heptachlor—were
used to guard soil and seed against insect infestation and to control
insect pests in crops. Outside of agriculture they were used for ant
control; farm, industrial, and domestic control of fleas, flies, lice,
and mites; locust control; termite control in buildings, fences, and
power poles; and pest control in home gardens. No other commercial use
is permitted for cyclodiene or related products. The only exception is
the use of heptachlor by utility companies to control fire ants in
underground cable boxes.
An EPA survey [53] revealed that bathrooms and kitchens are areas in
the home most likely to have improperly stored pesticides. In the
United States, EPA regulates pesticides under the pesticide law known
as the Federal Insecticide, Fungicide, and Rodenticide Act. Since
1981, this law has required most residential-use pesticides to bear a
signal word such as “danger” or “warning” and to be contained in
child-resistant packaging. This type of packaging is designed to
prevent or delay access by most children under the age of 5 years. EPA
offers the following recommendations for preventing accidental
poisoning:
- store pesticides away from the reach of children in a locked
cabinet, garden shed, or similar location;
- read the product label and follow all directions exactly,
especially precautions and restrictions;
- remove children, pets, and toys from areas before applying
pesticides;
- if interrupted while applying a pesticide, properly close the
package and assure that the container is not within reach of
children;
- do not transfer pesticides to other containers that children may
associate with food or drink;
- do not place rodent or insect baits where small children have
access to them;
- use child-resistant packaging properly by closing the container
tightly after use;
- assure that other caregivers for children are aware of the
potential hazards of pesticides;
- teach children that pesticides are poisons and should not be
handled; and
- keep the local Poison Control Center telephone number available.
Toxic Materials
Asbestos
Asbestos, from the Greek word meaning “inextinguishable,” refers to a
group of six naturally occurring mineral fibers. Asbestos is a mineral
fiber of which there are several types: amosite, crocidiolite,
tremolite, actinolite, anthrophyllite, and chrysotile. Chrysotile
asbestos, also known as white asbestos, is the predominant commercial
form of asbestos. Asbestos is strong, flexible, resistant to heat and
chemical corrosion, and insulates well. These features led to the use
of asbestos in up to 3,000 consumer products before government
agencies began to phase it out in the 1970s because of its health
hazards. Asbestos has been used in insulation, roofing, siding, vinyl
floor tiles, fireproofing materials, texturized paint and
soundproofing materials, heating appliances (such as clothes dryers
and ovens), fireproof gloves, and ironing boards. Asbestos continues
to be used in some products, such as brake pads. Other mineral
products, such as talc and vermiculite, can be contaminated with
asbestos.
The health effects of asbestos exposure are numerous and varied.
Industrial studies of workers exposed to asbestos in factories and
shipyards have revealed three primary health risk concerns from
breathing high levels of asbestos fibers: lung cancer, mesothelioma (a
cancer of the lining of the chest and the abdominal cavity), and
asbestosis (a condition in which the lungs become scarred with fibrous
tissue).
The risk for all of these conditions is amplified as the number of
fibers inhaled increases. Smoking also enhances the risk for lung
cancer from inhaling asbestos fibers by acting synergistically. The
incubation period (from time of exposure to appearance of symptoms) of
these diseases is usually about 20 to 30 years. Individuals who
develop asbestosis have typically been exposed to high levels of
asbestos for a long time. Exposure levels to asbestos are measured in
fibers per cubic centimeter of air. Most individuals are exposed to
small amounts of asbestos in daily living activities; however, a
preponderance of them do not develop health problems. According to the
Agency for Toxic Substances and Disease Registry (ATSDR), if an
individual is exposed, several factors determine whether the
individual will be harmed [54]. These factors include the dose (how
much), the duration (how long), and the fiber type (mineral form and
distribution).
ATSDR also states that children may be more adversely affected than
adults [54]. Children breathe differently and have different lung
structures than adults; however, it has not been determined whether
these differences cause a greater amount of asbestos fibers to stay in
the lungs of a child than in the lungs of an adult. In addition,
children drink more fluids per kilogram of body weight than do adults
and they can be exposed through asbestos-contaminated drinking water.
Eating asbestos-contaminated soil and dust is another source of
exposure for children. Certain children intentionally eat soil and
children’s hand-to-mouth activities mean that all young children eat
more soil than do adults. Family members also have been exposed to
asbestos that was carried home on the clothing of other family members
who worked in asbestos mines or mills. Breathing asbestos fibers may
result in difficulty in breathing. Diseases usually appear many years
after the first exposure to asbestos and are therefore not likely to
be seen in children. But people who have been exposed to asbestos at a
young age may be more likely to contract diseases than those who are
first exposed later in life. In the small number of studies that have
specifically looked at asbestos exposure in children, there is no
indication that younger people might develop asbestos-related diseases
more quickly than older people. Developing fetuses and infants are not
likely to be exposed to asbestos through the placenta or breast milk
of the mother. Results of animal studies do not indicate that exposure
to asbestos is likely to result in birth defects.
A joint document issued by CPSC, EPA, and ALA, notes that most
products in today’s homes do not contain asbestos. However, asbestos
can still be found in products and areas of the home. These products
contain asbestos that could be inhaled and are required to be labeled
as such. Until the 1970s, many types of building products and
insulation materials used in homes routinely contained asbestos. A
potential asbestos problem both inside and outside the home is that of
vermiculite. According to the USGS [55], vermiculite is a claylike
material that expands when heated to form wormlike particles. It is
used in concrete aggregate, fertilizer carriers, insulation, potting
soil, and soil conditioners. This product ceased being mined in 1992,
but old stocks may still be available. Common products that contained
asbestos in the past and conditions that may release fibers include
the following:
- Steam pipes, boilers, and furnace ducts insulated with an
asbestos blanket or asbestos paper tape. These materials may release
asbestos fibers if damaged, repaired, or removed improperly.
- Resilient floor tiles (vinyl asbestos, asphalt, and rubber), the
backing on vinyl sheet flooring, and adhesives used for installing
floor tile. Sanding tiles can release fibers, as may scraping or
sanding the backing of sheet flooring during removal.
- Cement sheet, millboard, and paper used as insulation around
furnaces and wood-burning stoves. Repairing or removing appliances
may release asbestos fibers, as may cutting, tearing, sanding,
drilling, or sawing insulation.
- Door gaskets in furnaces, wood stoves, and coal stoves. Worn
seals can release asbestos fibers during use.
- Soundproofing or decorative material sprayed on walls and
ceilings. Loose, crumbly, or water-damaged material may release
fibers, as will sanding, drilling, or scraping the material.
- Patching and joint compounds for walls, ceilings, and textured
paints. Sanding, scraping, or drilling these surfaces may release
asbestos.
- Asbestos cement roofing, shingles, and siding. These products
are not likely to release asbestos fibers unless sawed, drilled, or
cut.
- Artificial ashes and embers sold for use in gas-fired fireplaces
in addition to other older household products such as fireproof
gloves, stove-top pads, ironing board covers, and certain hair
dryers.
- Automobile brake pads and linings, clutch facings, and gaskets.
Homeowners who believe
material in their home may be asbestos should not disturb the
material. Generally, material in good condition will not release
asbestos fibers, and there is little danger unless the fibers are
released and inhaled into the lungs. However, if disturbed, asbestos
material may release asbestos fibers, which can be inhaled into the
lungs. The fibers can remain in the lungs for a long time, increasing
the risk for disease. Suspected asbestos-containing material should be
checked regularly for damage from abrasions, tears, or water. If
possible, access to the area should be limited. Asbestos-containing
products such as asbestos gloves, stove-top pads, and ironing board
covers should be discarded if damaged or worn. Permission and proper
disposal methods should be obtainable from local health,
environmental, or other appropriate officials. If asbestos material is
more than slightly damaged, or if planned changes in the home might
disturb it, repair or removal by a professional is needed. Before
remodeling, determine whether asbestos materials are present.
Only a trained professional can confirm suspected asbestos materials
that are part of a home’s construction. This individual will take
samples for analysis and submit them to an EPA-approved laboratory.
If the asbestos material is in good shape and will not be disturbed,
the best approach is to take no action and continue to monitor the
material. If the material needs action to address potential exposure
problems, there are two approaches to correcting the problem: repair
and removal.
Repair involves sealing or covering the asbestos material. Sealing or
encapsulation involves treating the material with a sealant that
either binds the asbestos fibers together or coats the material so
fibers are not released. This is an approach often used for pipe,
furnace, and boiler insulation; however, this work should be done only
by a professional who is trained to handle asbestos safely. Covering
(enclosing) involves placing something over or around the material
that contains asbestos to prevent release of fibers. Exposed insulated
piping may be covered with a protective wrap or jacket. In the repair
process, the approach is for the material to remain in position
undisturbed. Repair is a less expensive process than is removal.
With any type of repair, the asbestos remains in place. Repair may
make later removal of asbestos, if necessary, more difficult and
costly. Repairs can be major or minor. Both major and minor repairs
must be done only by a professional trained in methods for safely
handling asbestos.
Removal is usually the most expensive and, unless required by state or
local regulations, should be the last option considered in most
situations. This is because removal poses the greatest risk for fiber
release. However, removal may be required when remodeling or making
major changes to the home that will disturb asbestos material. In
addition, removal may be called for if asbestos material is damaged
extensively and cannot be otherwise repaired. Removal is complex and
must be done only by a contractor with special training. Improper
removal of asbestos material may create more of a problem than simply
leaving it alone.
Lead
Many individuals recognize lead in the form often seen in tire
weights and fishing equipment, but few recognize its various forms in
and around the home. The Merriam-Webster Dictionary [56] defines lead
as “a heavy soft malleable ductile plastic but inelastic bluish white
metallic element found mostly in combination and used especially in
pipes, cable sheaths, batteries, solder, and shields against
radioactivity.” Lead is a metal with many uses. It melts easily and
quickly. It can be molded or shaped into thin sheets and can be drawn
out into wire or threads. Lead also is very resistant to weather
conditions. Lead and lead compounds are toxic and can present a severe
hazard to those who are overexposed to them. Whether ingested or
inhaled, lead is readily absorbed and distributed throughout the body.
Until 1978, lead compounds were an important component of many paints.
Lead was added to paint to promote adhesion, corrosion control,
drying, and covering. White lead (lead carbonate), linseed oil, and
inorganic pigments were the basic components for paint in the 18th and
19th centuries, and continued until the middle of the 20th century.
Lead was banned by CPSC in 1978. Lead-based paint was used extensively
on exteriors and interior trim-work, window sills, sashes, window
frames, baseboards, wainscoting, doors, frames, and high-gloss wall
surfaces, such as those found in kitchens and bathrooms. The only way
to determine which building components are coated with lead paint is
through an inspection for lead-based paint. Almost all painted metals
were primed with red lead or painted with lead-based paints. Even milk
(casein) and water-based paints (distemper and calcimines) could
contain some lead, usually in the form of hiding agents or pigments.
Varnishes sometimes contained lead. Lead compounds also were used as
driers in paint and window-glazing putty.
Lead is widespread in the environment. People absorb lead from a
variety of sources every day. Although lead has been used in numerous
consumer products, the most important sources of lead exposure to
children and others today are the following:
- contaminated house dust that has settled on horizontal surfaces,
- deteriorated lead-based paint,
- contaminated bare soil,
- food (which can be contaminated by lead in the air or in food
containers, particularly lead-soldered food containers),
- drinking water (from corrosion of plumbing systems), and
- occupational exposure or hobbies.
Federal controls on lead in gasoline, new paint, food canning, and
drinking water, as well as lead from industrial air emissions, have
significantly reduced total human exposure to lead. The number of
children with blood lead levels above 10 micrograms per deciliter (µg/dL),
a level designated as showing no physiologic toxicity, has declined
from 1.7 million in the late 1980s to 310,000 in 1999–2002. This
demonstrates that the controls have been effective, but that many
children are still at risk. CDC data show that deteriorated lead-based
paint and the contaminated dust and soil it generates are the most
common sources of exposure to children today. HUD data show that the
number of houses with lead paint declined from 64 million in 1990 to
38 million in 2000 [57].
Children are more vulnerable to lead poisoning than are adults.
Infants can be exposed to lead in the womb if their mothers have lead
in their bodies. Infants and children can swallow and breathe lead in
dirt, dust, or sand through normal hand-to-mouth contact while they
play on the floor or ground. These activities make it easier for
children to be exposed to lead. Other sources of exposure have
included imported vinyl miniblinds, crayons, children’s jewelry, and
candy. In 2004, increases in lead in water service pipes were observed
in Washington, D.C., accompanied by increases in blood lead levels in
children under the age of 6 years who were served by the water system [58].
In some cases, children swallow nonfood items such as paint chips.
These may contain very large amounts of lead, particularly in and
around older houses that were painted with lead-based paint. Many
studies have verified the effect of lead exposure on IQ scores in the
United States. The effects of lead exposure have been reviewed by the
National Academy of Sciences [59].
Generally, the tests for blood lead levels are from drawn blood, not
from a finger-stick test, which can be unreliable if performed
improperly. Units are measured in micrograms per deciliter and reflect
the 1991 guidance from the Centers of Disease Control [60]:
- Children: 10 µg/dL (level of concern)—find source of lead;
- Children: 15 µg/dL and above—environmental intervention,
counseling, medical monitoring;
- Children: 20 µg/dL and above—medical treatment;
- Adults: 25 µg/dL (level of concern)—find source of lead; and
- Adults: 50 µg/dL—Occupational Safety and Health Administration (OSHA)
standard for medical removal from the worksite.
Adults are usually exposed to lead from occupational sources (e.g.,
battery construction, paint removal) or at home (e.g., paint removal,
home renovations).
In 1978, CPSC banned the use of lead-based paint in residential
housing. Because houses are periodically repainted, the most recent
layer of paint will most likely not contain lead, but the older layers
underneath probably will. Therefore, the only way to accurately
determine the amount of lead present in older paint is to have it
analyzed.
It is important that owners of homes built before 1978 be aware that
layers of older paint can contain a great deal of lead. Guidelines on
identifying and controlling lead-based paint hazards in housing have
been published by HUD [61].
Click here for terms related to lead.
Controlling Lead Hazards
The purpose of a home risk assessment is to determine, through testing
and evaluation, where hazards from lead warrant remedial action. A
certified inspector or risk assessor can test paint, soil, or lead
dust either on-site or in a laboratory using methods such as x-ray
fluorescence (XRF) analyzers, chemicals, dust wipe tests, and atomic
absorption spectroscopy. Lists of service providers are available by
calling 1-800-424-LEAD. Do-it-yourself test kits are commercially
available; however, these kits do not tell you how much lead is
present, and their reliability at detecting low levels of lead has not
been determined. Professional testing for lead in paint is
recommended. The recommended sampling method for dust is the surface
wet wipe. Dust samples are collected from different surfaces, such as
bare floors, window sills, and window wells. Each sample is collected
from a measured surface area using a wet wipe, which is sent to a
laboratory for testing. Risk assessments can be fairly low-cost
investigations of the location, condition, and severity of lead
hazards found in house dust, soil, water, and deteriorating paint.
Risk assessments also will address other sources of lead from hobbies,
crockery, water, and work environments. These services are critical
when owners are seeking to implement measures to reduce suspected lead
hazards in housing and day-care centers or when extensive
rehabilitation is planned.
HUD has published detailed protocols for risk assessments and
inspections [61].
It is important from a health standpoint that future tenants,
painters, and construction workers know that lead-based paint is
present, even under treated surfaces, so they can take precautions
when working in areas that will generate lead dust. Whenever
mitigation work is completed, it is important to have a clearance test
using the dust wipe method to ensure that lead-laden dust generated
during the work does not remain at levels above those established by
the EPA and HUD. Such testing is required for owners of most housing
that is receiving federal financial assistance, such as Section 8
rental housing. A building or housing file should be maintained and
updated whenever any additional lead hazard control work is completed.
Owners are required by law to disclose information about lead-based
paint or lead-based paint hazards to buyers or tenants before
completing a sales or lease contract [62].
All hazards should be controlled as identified in a risk assessment.
Whenever extensive amounts of lead must be removed from a property, or
when methods of removing toxic substances will affect the environment,
it is extremely important that the owner be aware of the issues
surrounding worker safety, environmental controls, and proper
disposal. Appropriate architectural, engineering, and environmental
professionals should be consulted when lead hazard projects are
complex.
Following are brief explanations of the two approaches for controlling
lead hazard risks. These controls are recommended by HUD in HUD
Technical Guidelines for the Evaluation and Control of Lead-Paint
Hazards in Housing [61], and are summarized here to focus on special
considerations for historic housing:
Interim Controls. Short-term solutions include thorough dust removal
and thorough washdown and cleanup, paint film stabilization and
repainting, covering of lead-contaminated soil, and informing tenants
about lead hazards. Interim controls require ongoing maintenance and
evaluation.
Hazard Abatement. Long-term solutions are defined as having an
expected life of 20 years or more and involve permanent removal of
hazardous paint through chemicals, heat guns, or controlled sanding or
abrasive methods; permanent removal of deteriorated painted features
through replacement; removal or permanent covering of contaminated
soil; and the use of enclosures (such as drywall) to isolate painted
surfaces. The use of specialized encapsulant products can be
considered as permanent abatement of lead.
Reducing and controlling lead hazards can be successfully accomplished
without destroying the character-defining features and finishes of
historic buildings. Federal and state laws generally support the
reasonable control of lead-based paint hazards through a variety of
treatments, ranging from modified maintenance to selective substrate
removal. The key to protecting children, workers, and the environment
is to be informed about the hazards of lead, to control exposure to
lead dust and lead in soil and lead paint chips, and to follow
existing regulations.
The following summarizes several important regulations that affect
lead-hazard reduction projects. Owners should be aware that
regulations change, and they have a responsibility to check state and
local ordinances as well. Care must be taken to ensure that any
procedures used to release lead from the home protect both the
residents and workers from lead dust exposure.
Residential Lead-Based Paint Hazard Reduction Act of 1992, Title
X [62]. Part of the Housing and Community Development Act of 1992
(Public Law 102-550) [63]. It established that HUD issue Guidelines for
the Evaluation and Control of Lead-Based Paint Hazards in Housing [61]
to outline risk assessments, interim controls, and abatement of
lead-based paint hazards in housing. Title X calls for the reduction
of lead in federally supported housing. It outlines the federal
responsibility toward its own residential units and the need for
disclosure of lead in residences, even private residences, before a
sale. Title X also required HUD to establish regulations for federally
assisted housing (24 CFR Part 35) and EPA to establish standards for
lead in paint, dust, and soil, as well as standards for laboratory
accreditation (40 CFR Part 745). EPA’s residential lead hazard
standards are available at
http://www.epa.gov/lead/.
Interim Final Rule on Lead in Construction (29 Code of Federal
Regulations [CFR] 1926.62) [64]. Issued by OSHA, these regulations
address worker safety, training, and protective measures. The
regulations are based in part on personal-air sampling to determine
the amount of lead dust exposure to workers.
State Laws. States generally have the authority to regulate the
removal and transportation of lead-based paint and the generated waste
through the appropriate state environmental and public health
agencies. Most requirements are for mitigation in the case of a
lead-poisoned child, for protection of children, or for oversight to
ensure the safe handling and disposal of lead waste. When undertaking
a lead-based paint reduction program, it is important to determine
which laws are in place that may affect the project.
Local Ordinances. Check with local health departments, poison control
centers, and offices of housing and community development to determine
whether any laws require compliance by building owners. Determine
whether projects are considered abatements and will require special
contractors and permits.
Owner’s Responsibility. Owners are ultimately responsible for ensuring
that hazardous waste is properly disposed of when it is generated on
their own sites. Owners should check with their state government to
determine whether an abatement project requires a certified
contractor. Owners should establish that the contractor is responsible
for the safety of the crew, to ensure that all applicable laws are
followed, and that transporters and disposers of hazardous waste have
liability insurance as a protection for the owner. The owner should
notify the contractor that lead-based paint may be present and that it
is the contractor’s responsibility to follow appropriate work
practices to protect workers and to complete a thorough cleanup to
ensure that lead-laden dust is not present after the work is
completed. Renovation contractors are required by EPA to distribute an
informative educational pamphlet (Protect Your Family from Lead in
Your Home) to occupants before starting work that could disturb
lead-based paint (http://www.epa.gov/lead/)
Click here for lead
action levels.
Arsenic
Lead arsenate was used legally up to 1988 in most of the orchards in
the United States. Often 50 applications or more of this pesticide
were applied each year. This toxic heavy metal compound has
accumulated in the soil around houses and under the numerous orchards
in the country, contaminating both wells and land. These orchards are
often turned into subdivisions as cities expand and sprawl occurs.
Residues from the pesticide lead arsenate, once used heavily on apple,
pear, and other orchards, contaminate an estimated 70,000 to 120,000
acres in the state of Washington
alone, some of it in areas where agriculture has been replaced with
housing, according to state ecology department officials and others.
Lead arsenate, which was not banned for use on food crops until 1988,
nevertheless was mostly replaced by the pesticide
dichlorodiphenyltrichloroethane (DDT) and its derivatives in the late
1940s. DDT was banned in the United States in 1972, but is used
elsewhere in the world.
For more than 20 years, the wood industry has infused green wood with
heavy doses of arsenic to kill bugs and prevent rot. Numerous studies
show that arsenic sticks to children’s hands when they play on treated
wood, and it is absorbed through the skin and ingested when they put
their hands in their mouths. Although most uses of arsenic wood
treatments were phased out by 2004, an estimated 90% of existing
outdoor structures are made of arsenic-treated wood [65].
In a study conducted by the University of North Carolina Environmental
Quality Institute in Asheville, wood samples were analyzed and showed
that
- Older decks and play sets (7 to 15 years old) that were
preserved with chromated copper arsenic expose people to just as
much arsenic on the wood surface as do newer structures (less than 1
year old). The amount of arsenic that testers wiped off a small area
of wood about the size of a 4-year-old’s handprint typically far exceeds what EPA allows in a
glass of water under the Safe Drinking Water Act standard.
Figure
5.9 shows a safety warning label placed on wood products.
- Arsenic in the soil from two of every five backyards or parks
tested exceeded EPA’s Superfund cleanup level of 20 ppm.
Arsenic is not just poisonous in the short term, it causes cancer in
the long term. Arsenic is on EPA’s short list of chemicals known to
cause cancer in humans. According to the National Academy of
Sciences, exposure to arsenic causes lung, bladder, and skin cancer
in humans, and is suspected as a cause of kidney, prostate, and
nasal passage cancer.
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