Dennis
J. Murphy and Cathleen M. LaCross
Pennsylvania State University Cooperative Extension
Farming
is filled with respiratory hazards: pesticide vapors, dusty
fields, dangerous hydrogen sulfide accumulations in manure
pits and pump sumps, nitrogen dioxide in conventional silos,
and many others. Farmer's Lung and Organic Dust Toxicity Syndrome
(ODTS) are allergic reactions to dust from moldy hay or grain
and may result in costly medical treatment, permanent lung
damage or death.
In many
cases, a five- to twenty-five-dollar respirator could have
prevented farmers from acquiring nagging, permanent lung damage
caused by longterm exposure to dusts, mists, gases, and vapors.
But choosing a respirator can be very confusing -- there are
so many different kinds on the market today.
The
first step to choosing a respirator is determining what kind
of hazard you'll be facing (see Table 1). There are three basic
categories of respiratory hazards on the farm. The first category,
particulate contaminants, includes dusts, mists, and fumes.
Dusts are usually the largest particles, but not all dusts can
be seen with the naked eye. Mold spores, for example, are microscopic.
They're released when moldy hay, silage, or grain is disturbed.
Mists are suspended liquid droplets an are usually found near
mixing, spraying, and cleaning operations. Fumes are solid particles
of evaporated metal. They're microscopic as well and are formed
during activities such as welding.
Table
1. Required Protection for Respiratory Hazards |
Respiratory
Hazard
| Required
Protection
|
Pesticide
dusts, mists, vapors, and gasses |
A
NIOSH-approved chemical cartridge respirator or gas mask
with added pro-filter. For extremely high gases concentrations,
where the oxygen level may be low, wear a supplied-air
respirator. Refer to pesticide container label for additional
requirements. |
Mold
dust, grain dust, manure dust, dust from poultry operations,
road or field dust, and untreated sawdust |
A
NIOSH-approved mechanical filter respirator or dust/mist
mask approved for use with toxic dusts. |
Ammonia |
A
NIOSH-approved chemical cartridge respirator or gas mask
approved for use with ammonia. |
Hydrogen
sulfide (manure gas) |
Supplied-air
respirator approved by NIOSH. |
Nitrogen
dioxide (silo gas) |
Supplied-air
respirator approved by NIOSH. |
Welding
fumes |
A
NIOSH-approved mechanical filter respirator approved for
use with fumes. |
Spray
paint mists |
A
NIOSH-approved mechanical filter respirator approved for
use with spray paints or organic vapor cartridge with
paint prefilter on chemical cartridge respirator. |
Carbon
monoxide (gas-powered vehicle or machinery exhaust) |
A
NIOSH-approved gas mask or supplied-air respirator. |
Fumigants |
CAUTION:
Fumigants are highly penetrating and some can penetrate
the rubber and plastic parts on respirators. In addition,
some are colorless and odorless and give no warning of
exposure. Many respirators approved for pesticides are
NOT approved for protection against fumigants. For the
best protection, completely avoid fumigants and treated
areas yourself and leave entry into treated areas to trained
professionals. |
The
second category of hazards is gases and vapors. Vapors evaporate
from liquids, such as pesticides, paints, adhesives, and lacquer
thinner. Gases are chemicals that are gaseous at room temperature.
Examples include hydrogen sulfide, the deadly manure pit gas;
nitrogen dioxide, which can be found in conventional silos;
and carbon monoxide from running internal combustion engines.
The
third category of hazards is oxygen-deficient atmospheres.
Examples of oxygen-deficient atmospheres include manure storage's,
oxygen-limiting (sealed) silos and controlled atmospheres
(CA) storages for fruits and vegetables. In such structures,
the oxygen content of breathable air, normally about 21 %,
is reduced to levels as low as 5%. The reduction in oxygen
may occur deliberately, such as with CA storages, or is displaced
by other gases as in manure storage's and conventional silos.
Once
you've pinpointed the hazard (or hazards), and before resorting
to a respirator, try to reduce or eliminate the source of
the problem. For example, maybe you could use different management
practices when harvesting and storing crops to reduce dust
and mold. Perhaps you need better ventilation in your barn.
Can you work outdoors instead of in an enclosed building?
Or maybe you could be using a non-toxic, less toxic, or less
volatile pesticide. After you've tried to reduce or eliminate
the hazard, if you're still at risk, use a respirator.
There is no such thing as an all-purpose respirator. There are
specific respirators for specific contaminants, so choose your
respirator carefully. But no matter what kind or brand of respirator
you choose, it should be approved by the National Institute
for Occupational Safety and Health (NIOSH) or the Mine Safety
and Health Administration (MSHA). If the respirator or filter
has a number preceded by the prefix "TC," you can be assured
that it is approved.
Air-Purifying
Respirators There are
two categories of respirators, airpurifying and supplied air.
The first, AIRPURIFYING RESPIRATORS, are equipped with filters
through which the wearer breathes. IMPORTANT: These respirators
do not supply oxygen. Therefore, they should not be worn in
areas considered immediately dangerous to life or health (IDLH),
such as oxygen-deficient areas (oxygen-limiting silos, for example)
or highly toxic atmospheres, like those sometimes found in manure
storage pits. Air-purifying respirators are good in areas such
as barn lofts with moldy hay, fields during tilling or pesticide
application, or construction sites where fiberglass or wood
dusts are likely to be found.
Because
the wearer must pull air through the filter, all air-purifying
respirators put added stress on you. For this reason, if you
suffer or suspect that you suffer from respiratory problems
such as asthma, lung or cardiovascular disease, check with
a doctor to make sure you're able to wear one. There are several
types of air-purifying respirators.
Mechanical
Filter Respirators Mechanical
filter respirators protect you from particulate contaminants:
dusts, mists, or metal fumes. The filters are made of a fibrous
material that traps particles as you inhale. These respirators
are useful during operations such as haying, harvesting, tilling
dusty fields, applying fertilizer and lime, grinding feed, and
sweeping. Both disposable and reusable masks are available.
Disposable masks are more convenient-you simply throw them away
when they're saturated. Reusable masks, o the other hand, may
save you money in the long run and create less waste. Usually
a single respirator offers protection only against dusts and
mists but a few will protect against dusts, mists and fumes.
Filters
and disposable masks should be replaced when breathing becomes
too labored, when the mask loses its shape and no longer seals
well to your face, or if you taste or smell the substance.
In general, the common dust mask found in hardware stores,
often labeled as a "nuisance dust mask," is not considered
a respirator and will not provide suitable protection from
particulates. Nuisance dust masks are most easily distinguished
by their single elastic strap. NIOSH has approved a few dust
asks for use with some toxic dusts and mists, such as dry
fertilizer and molds. They will not, however, provide adequate
protection from pesticide dusts and mists. Approved models
have two elastic straps in back for a better seal. Look for
a "TC" number to be sure yours is approved. Mechanical
filter respirators should not be worn in areas considered
IDLH.
Chemical
Cartridge Respirators Chemical
cartridge respirators filter out low concentrations of toxic
gases and vapors. An absorbent material such as activated charcoal
absorbs contaminants from inhaled air. These masks can also
be equipped with particulate filters, so if you'll be exposed
to gases or vapors and dusts or mists, this is the kind of respirator
you should wear. There are half-mask models and full-face models;
the latter provides eye and face protection as well. The half
masks are also available in disposable or reusable models.
The
filtering cartridges for these respirators screw onto the
front of the mask. There are specific cartridges for specific
contaminants, so make sure you have the right cartridge for
the hazard you're facing. For example, there are cartridges
specifically made for use with pesticides; others contain
different absorbents to filter out ammonia. The cartridges
are changeable, so if you have a reusable mask you can use
it for any gas or vapor contaminant, provided you have the
right cartridge
Cartridges
should be replaced after eight hours use or when "breakthrough"
occurs -- that is, when you begin to smell or taste the contaminant
or when dizziness or irritation occurs. Make sure the cartridge
brand matches the respirator brand. Manufacturers use different
threads which prevents mismatched brands (respirators and
cartridges) from sealing properly. Chemical cartridge respirators
should not be worn in areas considered immediately dangerous
to life or health (IDLH).
Gas
Masks Gas masks,
or chemical canister respirators, are very similar to chemical
cartridge respirators except they can be used in areas where
gases are extremely toxic or highly concentrated. The canisters
hold more chemical sorbent than cartridges, so they have a greater
filtering capacity and last longer. Canisters can be mounted
on a belt, worn on the back or chest, or they can be screwed
onto the mask beneath the chin. They're connected to the facepiece
by an air hose.
Gas
masks are only available with a full facepiece. The canister
should be replaced after eight hours use or when "breakthrough"
occurs. Gas masks should not be worn in areas considered IDLK.
Powered
Air-Purifying Respirators (PAPRS)A PAPR is
simply an air-purifying respirator with a motorized blower that
forces air through the filtering device. It makes breathing
easier for the wearer, so this type of respirator may be recommended
by a doctor for someone with a minor respiratory or cardiovascular
ailment. They tend to be cooler, too, because there is a constant
stream of air over the wearer's face and head. Many PAPRs have
a hard helmet and rigid visor under which the air is blown.
There are also half-mask and full-face models and models with
nonrigid helmets available.
PAPRs
can be used for dusts, mists, gases, and vapors, provided
you have the right filters. The blower is powered by a battery
pack strapped onto the wearer's waist or back. Rechargeable
or disposable D-cell batteries can be used -- most batteries
last 6-8 hours. Or you can use a 12V or 24V DC adapter, which
will run the blower from a vehicle battery. Powered air-purifying
respirators should not be worn in areas considered immediately
dangerous to life or health (IDLH).
Supplied-Air
Respirators The other
category of respirators, SUPPLIED-AIR RESPIRATORS, are the only
kind to be used in areas considered IDLH. These respirators
can be used in manure pits, sealed silos, or fumigated bins
containing high-moisture grain. They supply the wearer with
fresh, clean air from an outside source. There are two types
of supplied-air respirators. The first, air line respirators,
provide clean air through a hose that is connected to a stationary
air pump or tank. The second, a self-contained breathing
apparatus, or SCBA, has a portable air tank that is carried
on the back like those worn by scuba divers and firefighters.
Supplied-air
respirators are undeniably very expensive to buy and maintain,
and instruction and practice are necessary to use one correctly.
Farmers should understand, however, that every time they enter
a sealed silo or manure pit without one, they're risking their
lives. Many farmers underestimate the danger associated with
such areas. Dangerous gases can build up in IDLH areas, creating
a lethal, oxygen-deficient atmosphere that can kill you, literally,
in seconds -- faster than anyone can attempt a rescue. Unless
you are wearing a supplied-air respirator or have the atmosphere
inside the area monitored for dangerous gases, you can never
be sure. Don't become a statistic. Just because you successfully
entered the pit the last time doesn't mean you will this time.
Contact an industrial hygienist or your local fire department
-- perhaps they have a supplied-air respirator you can borrow
if you feel you must enter an IDLH area. The hazards of manure
pits and silo gases are more fully described in the Agricultural
Engineering Fact Sheets Safety-16, "Silo Gases-The Hidden
Danger," and Safety-28, "Manure Storage Hazards."
Once
you have decided what kind of respirator you need, visit your
local farm supply store, ag chemical supplier, hardware store,
or industrial safety equipment company. Try on several brands
and styles of respirators to see which is the most comfortable
for you. They come in all shapes and sizes, so it's smart to
try before you buy.
Also,
if possible before you buy, contact an industrial hygienist
to find out where you can get a fit test. If not possible
before buying, be sure to do this after the purchase but realize
you may not get a good fit with the one you now have. A fit
test is administered by a trained person to make sure your
respirator has a good seal. It should be done before wearing
any new respirator and once a year in subsequent years. During
the test, you will be asked to put on your respirator, adjust
t, and move your head around and talk while an irritating
smoke or strong odor is waved around your head. If you can't
detect any irritation or odor, your mask has a good seal.
Every
time you put on an air-purifying respirator, conduct a fit
check. This is something you can do yourself. Place your palms
over the exhale port on approved respirators, and exhale.
The respirator should slightly push out from your face. Next
cover the inhale ports, or filters, and inhale for 10 seconds.
The respirator should suck back onto your face and maintain
good suction for the entire 10 seconds. If you do not get
a good seal, readjust straps or reposition the respirator
and re o the check. When wearing a respirator, if at any time
the seal breaks and you begin to smell or taste a contaminant
or if you experience dizziness, nausea, or irritation, get
out of the contaminated area and into fresh air immediately.
Periodically
inspect your respirator for damage and dirt. Look for excessive
dirt around the facepiece, detergent residue, missing valve
covers, a cracked facepiece, breaks or tears in the headstraps,
or loss of elasticity in the headstraps. NEVER attempt to
repair a damaged respirator beyond replacing replaceable parts,
such as filter's and headstraps. Call the manufacturer to
see if they supply parts for your particular respirator. Don't
try to substitute parts from other respirators that might prevent
a total seal.
Glasses,
gum or tobacco chewing, facial hair, or even stubble can prevent
your respirator from sealing properly also. A human hair is
an average of 10 microns in diameter-, contaminants can be
anywhere from 0.2 to 16 microns in diameter. You should be
clean-shaven if you want the utmost protection. If you wear
prescription glasses, adapters are available for securing
prescription lenses inside the facepiece of a full-face respirator.
Don't wear contacts with respirators; in any contaminate environment
contaminants can stick to contacts and cause damage to your
eyes.
Clean
your respirator often in warm, soapy water. (Remember to remove
all cartridges and filters first!) After it is thoroughly
dry, store it in a sealed plastic bag. If you leave the respirator
out in the open with the cartridges and filter attached, cartridges
can adsorb vapors and filters can collect dust from the air
and become saturated. Duct tape may be placed over the face
of the cartridge or filter to prevent further exposure to
dusts or vapors in the environment.
Respirators
can prevent many respiratory ailments associated with farming
-- but only if you wear one! Make sure you choose the right
type of respirator for the hazard or hazards you'll be facing
(see Table 1). Before long, wearing it will become habit. If
you maintain it and clean it regularly, the small investment
a respirator costs you now might save you and your family the
expense of large medical bills later in life. For more information
on respiratory hazards and protection, contact county extension
offices, industrial hygienists, safety and health professionals,
or respiratory protection manufacturers.
Disclaimer
and Reproduction Information: Information in NASD does not represent
NIOSH policy. Information included in NASD appears by permission
of the author and/or copyright holder. More
NASD Review: 04/2002
This document was
published in 1993 as Pennsylvania State University Fact Sheet
Safety
36
,
Pennsylvania Cooperative Extension Service. For more information,
contact Pennsylvania State University College of Agricultural
Sciences, Agricultural Engineering Department, 246 Agricultural
Engineering Building, University Park, PA 16802. Dennis J. Murphy,
professor; Cathleen M. LaCross, technical writer; Agricultural
Engineering Department, Cooperative Extension Service, Pennsylvania
State University, University Park, PA 16802.
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