Contents
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the National Institute for Occupational Safety and Health.
This document is in the public domain and may be freely copied or
reprinted.
To purchase individual published reports listed in this document or
to order the CD-ROM collection of selected published Health Hazard
Evaluation Reports from 1980 to 1996, contact the National Technical
Information Service (NTIS) as follows:
National Technical Information
Service
5285 Port Royal Road
Springfield, VA 22161
1-800-533-NTIS (1-800-533-6847)
www.ntis.gov
To order single copies of closeout letters and final reports listed
in this document, please send your request (including the HETA reference
number) and a self-addressed, stamped envelope to the Hazard Evaluations
and Technical Assistance Branch (HETAB) as follows:
National Institute for Occupational Safety
and Health
Hazard Evaluations and Technical Assistance Branch
4676 Columbia Parkway, R 9
Cincinnati, OH 45226 1998
1-513-841-4252
www.cdc.gov/niosh/hhe.html
To make general inquiries about any of the reports contained in this
document, call the TB Project Officer, HETAB, at 1-513-841-4374.
To receive information about other occupational safety and health
topics, call 1-800-35-NIOSH (1-800-356-4674), or visit the NIOSH Web
site at
http://www.cdc.gov/niosh/.
U.S. Department of Health and Human Services
Public Health Service
Centers for Disease Control and Prevention
National Institute for Occupational Safety and Health
[ Top of Page ]
The Health Hazard Evaluations and Technical Assistance (HETA) Program
responds to requests from employers, employees, employee
representatives, other Federal agencies, and State and local agencies.
Through a staff of industrial hygienists, engineers, occupational
physicians, epidemiologists, other health professionals, and support
personnel, the Hazard Evaluations and Technical Assistance Branch
(HETAB) collaborates with appropriate personnel in other divisions of
the National Institute for Occupational Safety and Health (NIOSH) to
respond to approximately 400 requests for assistance each year. The
typical HETA response to a request for assistance results in (1) an
evaluation of whether chemical, physical, biological, or other agents
are hazardous as used or found in the workplace and (2) the development
of recommendations for control procedures, improved work practices, and
medical programs to reduce exposure levels and prevent adverse health
effects. The results of individual evaluations may trigger wider studies
of similar exposures in other settings or may stimulate recommendations
for implementation or modification of health standards. More than 10,000
evaluations have been completed since the inception of the HETA Program
in 1972. Requests received by the HETA Program tend to reflect emerging
occupational problems, such as tuberculosis (TB) in the workplace and
other National Occupational Research Agenda (NORA) priority areas.
The TB-related Health Hazard Evaluation (HHE) Project administers
HHEs of occupational exposure to TB. Site visits are conducted if
warranted, and interim and final reports are developed and distributed
to the employer, employees, and relevant State and Federal agencies.
Seventy-seven TB-related HHEs were requested from 1990 to 1999. The HHE
requests came from a variety of workplaces, including hospitals,
neighborhood health centers, TB clinics, homeless shelters, drug
treatment centers, correctional facilities, social service facilities,
laboratories, medial waste treatment facilities, and an inspection
station for imported non-human primates.
This document presents titles and summaries of HHEs related to TB,
organized by type of facility. In most cases TB exposure was just one of
several exposures that NIOSH researchers investigated at a work site. In
many cases, corrective measures were made in response to the evaluation
and recommendations made by NIOSH investigators.
Lawrence J. Fine, M.D., Dr.P.H.
Acting Director
National Institute for Occupational Safety and Health
[ Top of Page ]
Faye T. Bresler, M.D., M.P.H.
Yvonne Boudreau, M.D., M.S.P.H.
Teresa M. Buchta, M.S.
Nancy Clark Burton, M.P.H., M.S., C.I.H.
Michael S. Crandall, M.S., C.I.H.
John A. Decker, M.S., C.I.H.
Scott Deitchman, M.D., M.P.H.
Richard Driscoll, Ph.D.
Charles S. Hayden II, B.S.
Edward Hoekstra, M.D.
Robert T. Hughes, Ph.D., P.E.
Paul Jensen, Ph.D., P.E., C.I.H.
John Kelly, M.S.
Matthew Klein, P.E.
Greg J. Kullman, Ph.D., C.I.H.
Charles S. McCammon, Ph.D., C.I.H.
Kenneth F. Martinez, M.S.E.E., C.I.H.
Aubrey Miller, M.D., M.P.H.
Vincent Mortimer, P.E.
C. Eugene Moss, H.P., C.S.S.
Lee Petsonk, M.D.
Teresa A. Seitz, M.P.H., C.I.H.
Ruth A. Shults, R.N., M.P.H.
William K. Sieber, Ph.D.
David Sylvain, M.S., C.I.H.
Allison Tepper, Ph.D.
Douglas B. Trout, M.D., M.H.S.
Randy L. Tubbs, Ph.D.
Angela M. Weber, M.S.
Edited by: Jane Weber, M.Ed. Teresa A.
Seitz, M.P.H., C.I.H.
Desktop Publishing by: Donna M.
Pfirman
Web conversion by: David K. Wall
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HETA 90-0122-2073
October 1990
Purpose: To investigate potential
occupational hazards related to germicidal lamps used to disinfect the
air in tuberculosis (TB) and aerosolized pentamidine (AP) clinics.
Keywords: SIC 8011 (Offices and Clinics of
Doctors of Medicine) and 8071 (Medical Laboratories), TB, skin testing,
ventilation.
Abstract: Because of concerns regarding the
ultraviolet (UV) exposure in this hospital and medical center, an
evaluation was undertaken of possible hazardous working conditions at
that site. Concern existed about exposures to hazards while operating
the germicidal lamps at this facility. Germicidal lamps were used to
disinfect the air in TB and AP clinics. All rooms used a 30-watt
germicidal lamp. Lower wattage bulbs in the smaller rooms would have
reduced occupational UV exposure. Reflectance levels of UV radiation
were quite high and varied. Worker exposure to germicidal lamp UV levels
was dependent on many factors, some of the most important ones being the
position of the bulb in the room, age of the bulb, obstruction of the UV
radiation by objects near the bulb, and the height of the worker. While
no consensus guidelines are available on ventilation systems designed
for areas where germicidal lamps are used, the provision of good room
air distribution and mixing is recommended to prevent stagnant air
conditions or short circuiting of supply air within the room. Bulb
changers need to be aware of the need for protective clothing and gloves
for protection from both the UV radiation levels as well as possible
glass breakage. Copies are available from HETAB.
HETA 90-0330-2479
December 1994
Purpose: To evaluate occupational exposure to
aerosolized pentamidine (AP) and purified protein derivative (PPD) skin
test conversion among employees administering AP treatments.
Keywords: SIC 8069 (Specialty Hospitals,
Except Psychiatric), pentamidine, pentamidine isethionate, AP,
tuberculosis (TB), health care worker, human immunodeficiency virus
(HIV), Pneumocystis carinii pneumonia.
Abstract: NIOSH representatives conducted
health hazard evaluations at four hospitals to evaluate exposures to AP
and to determine whether workers administering AP were at increased risk
of occupational TB transmission. The NIOSH evaluations included air
sampling for pentamidine during AP administration and a review of
employee health records to assess the rate of TB PPD skin test
conversion. The exposed respondents indicated that they gave an average
of 11 pentamidine treatments per week (range 0 to 20). None of the
employees who were PPD skin test negative before administrating AP had
converted to PPD positive on their most recent test. However, the most
recently reported tests for three employees had been administered more
than 1 year previously (ranging from 12 to 18 months). Personal
breathing zone concentrations of pentamidine ranged from non-detectable
to 46 µg/m3. Local exhaust ventilation was effective in
minimizing environmental contamination and worker exposures to
pentamidine and would also serve to reduce exposures to
Mycobacterium tuberculosis (M. tuberculosis) if present in
the environment. Recommendations to further reduce workers' exposures to
AP and to M. tuberculosis while caring for HIV-infected
patients and to improve medical surveillance programs for PPD skin test
conversion are contained in the full report. Copies are available from
NTIS, individually or on CD-ROM.
HETA 90-0350
January 1991
Purpose: To evaluate the ventilation systems,
work practices, and administrative procedures at this hospital in
conjunction with a separate investigation of possible nosocomial
transmission of tuberculosis (TB).
Keywords: SIC 8062 (General Medical and
Surgical Hospitals), TB, aerosolized pentamidine (AP), ventilation
system, health care workers.
Abstract: The NIOSH evaluation focused on an
inpatient Acquired Immunodeficiency Syndrome (AIDS) unit and a special
immunology clinic that performed AP administration and sputum induction.
A ventilation system evaluation was performed that included measurement
of the volume rate of air flow, the direction of airflow, and
quantitative determinations of air pressure differential between inside
the patient rooms and the corridors. Air change rates were calculated
from the air flow rate data and were compared with existing guidelines.
On the AIDS unit, approximately one-fourth of the patient rooms allowed
air to flow out into the corridor (i.e., they were under positive
pressure), and more than half of the rooms had an insufficient supply of
outside air. The special immunology clinic, the pentamidine
administration rooms, main treatment room, and several examination
rooms were under positive pressure and had an insufficient supply of
outside air. Air recirculation also existed in the main treatment room
and several examination rooms which allowed the introduction of
infectious aerosols escaping from the pentamidine room into these areas.
Based on the history of work practices and administrative controls and
on the results of the NIOSH evaluation, there was potential for employee
exposure to infectious microorganisms in the evaluated areas.
Recommendations were made to correct the ventilation deficiencies and
other procedural problems identified in the NIOSH evaluation.
Copies are available from HETAB.
HETA 91-0148-2236
July 1992
Purpose: To investigate exposure to
ultraviolet (UV) radiation emitted by germicidal lamps at a tuberculosis
(TB) clinic.
Keywords: SIC 8099 (Health and Allied
Services, Not Elsewhere Classified), germicidal ultraviolet (GUV)
radiation, TB clinic, ventilation.
Abstract: NIOSH representatives provided
assistance in documenting occupational exposure to UV radiation emitted
by germicidal lamps at this TB clinic. NIOSH personnel made GUV
radiation measurements on all lamps at the TB clinic. The results of
this evaluation showed that the levels of occupational exposure to GUV
radiation produced in most of the work areas were below the NIOSH
recommended exposure limit (REL) of 0.1 effective
µW/cm3. The only exceptions found were
GUV levels at very close distances to lamps. Other findings noted were
the presence of old lamps, inappropriate labeling and posting of signs,
and ventilation deficiencies in the TB clinic area. Based on GUV
radiation measurements, it was determined that a health hazard could
exist from exposure to the germicidal lamps at a distance of 10.2 cm or
closer if workers did not wear protective eyewear. Except for one
situation, exposure to GUV at distances greater than 10.2 cm did not
represent a health hazard on the day of measurement. Recommendations for
minimizing the UV exposures as well as improving certain ventilation
parameters were provided.
Copies are available from NTIS, individually or on CD-ROM.
HETA 91-0187-2544
November 1995
Purpose: To investigate nosocomial
transmission of tuberculosis (TB) in health care workers.
Keywords: SIC 8062 (General Medical and
Surgical Hospitals), TB, aerosolized pentamidine (AP) isethionate,
aerosolized pharmaceuticals, respirators, ventilation system, aerosol
containment system, health care workers, ultraviolet (UV) radiation,
germicidal lamps.
Abstract: A health hazard evaluation was
conducted by NIOSH researchers at this hospital to assess nosocomial
transmission of TB in health care workers. NIOSH investigators evaluated
the risk of tuberculin skin test (TST) conversion in employees exposed
to patients with infectious TB, the adequacy of ventilation in areas of
the hospital where patients with infectious TB are treated, the
potential for exposure to AP and to Mycobacterium tuberculosis
in workers who administered AP, and the potential for overexposure to
ultraviolet germicidal irradiation (UVGI) from UV lamps. The risk of TST
conversion was evaluated through a 4-year retrospective cohort study
among exposed (n=249) and unexposed (n=355) employees. Employees who
worked in areas where patients with active TB were cared for, including
workers who did not provide direct patient care, had a higher rate of
TST conversion than employees who did not work in these areas. A decline
in this elevated risk was seen over time. Reasons for the decline
include outbreak termination, fewer admissions of TB patients,
implementation of effective infection control measures, and possible
resistance to infection in some members of the study population. Some
hospital areas where patients with infectious TB are cared for had
inadequate ventilation. Workers who administered AP treatments to
patients had no increase in symptoms or risk of TB infection over
workers who did not administer these treatments. The potential for
overexposure to UV radiation existed for those who worked around
functioning UVGI lamps. Recommendations addressing each of these issues
are provided in the full report. Copies are available from NTIS,
individually or on CD-ROM. The study was published in the American
Journal of Industrial Medicine. (Boudreau AY, Baron SL, Steenland
NK, VanGilder TJ, Decker JA, Galson SK, and Seitz T. [1997] Occupational
Risk of Mycobacterium tuberculosis Infection in Hospital
Workers. Am J Ind Med 32: 528-534.)
HETA 92-0215-2268
November 1992
Purpose: To investigate the potential for
tuberculosis (TB) transmission at this TB hospital.
Keywords: SIC 8069 (Specialty Hospitals,
Except Psychiatric), TB, state hospital, ventilation, infection
control.
Abstract: NIOSH investigators performed a
health hazard evaluation (HHE) that included industrial hygiene and
medical components at a state TB hospital. The industrial hygiene
component focused on assessing the effectiveness of the ventilation
systems in use at the hospital. A visual inspection of the ventilation
systems and a review of the original specifications of the air-handling
units were completed by the investigators. Additionally, measurements
were made of the airflow from supply and exhaust diffusers in patient
rooms, along with temperature and relative humidity measurements. The
direction of airflow between patient rooms and hallways and between
hospital wards was also determined in several locations in the hospital
complex. The medical component consisted of a qualitative review of
current employee infection control practices. Some deficiencies were
noted in the ventilation systems that could potentially contribute to
the transmission of TB from infectious patients to other patients and
hospital staff. Recommendations to modify the ventilation systems to
meet isolation evaluation criteria are contained in the full report
along with recommendations to strengthen the hospital's employee skin
testing and infection control programs.
Copies are available from NTIS, individually or on CD-ROM.
HETA 92-0232-2767
November 1999
Purpose: To evaluate the risk of transmission
of Mycobacterium tuberculosis (M. tuberculosis) to
hospital workers.
Keywords: SIC 8062 (General Medical and
Surgical Hospitals), tuberculosis (TB), hospital workers, occupational
exposure, nosocomial transmission, tuberculin skin test.
Abstract: NIOSH investigators conducted an
epidemiologic study of the risk of M. tuberculosis transmission
(as defined by tuberculin skin test [TST] conversion) among hospital
workers with "patient contact" compared to workers with "no patient
contact." Hospital workers employed at the hospital from January 1,
1990, through September 30, 1992 were included in the retrospective
cohort study. Personal, community, and occupational risk factors for TST
conversion were evaluated in 2,362 workers with potential tuberculosis
exposure and 886 workers with little or no potential for exposure. Among
workers with potential exposure, statistically significantly elevated
risks for TST conversion were found for nurses, phlebotomists, emergency
room workers, housekeepers, clerks, and emergency responders. Among
nurses, the risk was related to a proxy measure of occupational TB
exposure (i.e., the number of positive M. tuberculosis cultures
from their work location).
Copies are available from NTIS.
HETA 92-0296-2243
August 1992
Purpose: To determine if ventilation
requirements for the isolation of tuberculosis (TB) patients were being
met at this medical center.
Keywords: SIC 8062 (General Medical and
Surgical Hospitals), TB, ventilation.
Abstract: NIOSH investigators conducted a
health hazard evaluation at this medical center to evaluate the
ventilation systems in an infectious disease ward. NIOSH investigators
made ventilation measurements to determine the status of the ventilation
systems serving the area. Smoke tube traces were used to determine
room-to-corridor pressure relationships and the pressure relationship of
the infectious disease ward to the core areas of the hospital. There was
a general flow of air out of the infectious disease ward and into the
core area. In fact, the air flowed through the core area and into an
adjacent wing of the hospital. This condition could cause the
circulation of infectious agents to other wards and floors of the
hospital because of shared heating, ventilating, and air conditioning
(HVAC) systems. On the basis of the measurements made during the
evaluation, there was no apparent isolation of infectious patients in
the infectious diseases ward. It was recommended that a separate
isolation facility be constructed in the hospital to house infectious TB
patients. Interim corrective measures for the systems in place were also
recommended.
Copies are available from NTIS, individually or on CD-ROM.
HETA 92-0298-2325
June 1993
Purpose: To investigate the ventilation
systems serving the isolation rooms for tuberculosis (TB) patients in
six hospitals.
Keywords: SIC 8062 (General Medical and
Surgical Hospitals), TB, ventilation, infection control.
Abstract: NIOSH investigators conducted a
health hazard evaluation to evaluate the ventilation systems serving the
isolation rooms for TB patients in six hospitals. A visual inspection of
the ventilation systems, as well as a review of the original
specifications of the air-handling units, was completed for each
facility. Where the ventilation systems were operating, airflow
measurements from supply and exhaust diffusers were made. Smoke tube
traces were used to determine room-to-corridor pressure relationships.
General information was gathered on employee tuberculin skin testing
programs. Some deficiencies were noted in the ventilation systems of
these facilities that could potentially contribute to the transmission
of TB from infectious patients to other patients, hospital staff, and
visitors. Recommendations to modify the ventilation systems so that
isolation evaluation criteria are met were offered in the full report,
along with recommendations to strengthen the infection control programs
at the facilities.
Copies are available from NTIS, individually or on CD-ROM.
HETA 93-0046
March 1995
Purpose: To investigate the collection of
environmental air samples for Mycobacterium tuberculosis
(M. tuberculosis).
Keywords: SIC 8069 (Specialty Hospitals,
Except Psychiatric), tuberculosis (TB), state hospital, ventilation,
infection control.
Abstract: This research was conducted to test
an experimental methodology for collecting environmental air samples for
M. tuberculosis. This hospital was selected for this
experimental study design based on the number of active TB patients
resident at any given time. Eighty culturable air samples were collected
in various locations throughout the hospital including three patient
rooms and two control locations. Subsequent analysis of sample plates
revealed no acid-fast bacilli. Numerous theories exist about to the
inability to culture M. tuberculosis from the air including the
appropriateness of the sampling method and the fastidiousness of the
organism. However, the infectious nature of the patients was not
suspected as a limiting factor considering that at least one of the
patients was identified as sputum smear positive one day prior to the
sampling efforts.
Copies are available from HETAB.
HETA 93-0652
November 1997
Purpose: To investigate occupational
exposures to Mycobacterium tuberculosis (M.
tuberculosis) at a medical center.
Keywords: SIC 8062 (General Medical and
Surgical Hospitals) tuberculosis (TB), medical centers, ventilation,
ultraviolet lamp.
Abstract: NIOSH investigators conducted an
environmental assessment regarding occupational exposures to M.
tuberculosis at a department of this medical center. The assessment
was conducted as a result of an epidemiologic investigation of suspected
nosocomial transmission of multidrug-resistant M. tuberculosis
at the facility in 1992. NIOSH personnel conducted an evaluation of the
medical center, examined the ventilation systems serving the isolation
and treatment rooms, and evaluated germicidal ultraviolet lamps that
were used as environmental controls. The ventilation system evaluation
included discussions with persons responsible for operation and
maintenance of the system and performance of airflow measurements. Some
of the isolation rooms operated under positive pressure at all times
with respect to surrounding areas. Specific recommendations regarding
the ventilation system and ultraviolet lamps evaluated during the survey
were offered in the closeout letter.
Copies are available from HETAB.
HETA 93-0746 and 93-0747
August 1995
Purpose: To investigate the potential for
occupational exposure to Mycobacterium tuberculosis among
employees in county health care facilities.
Keywords: SIC 8093 (Specialty Outpatient
Facilities, Not Elsewhere Classified), tuberculosis (TB), ventilation,
tuberculin skin testing.
Abstract: NIOSH investigators examined the
airflow between rooms and hallways, and the status of the germicidal
ultraviolet lamp contained in the facility nebulizer room. Inspection of
the air handling systems revealed no general maintenance problems.
Investigators found that the close proximity between the outdoor air
intake and system exhaust could lead to reintrainment of exhausted air
back into the system and subsequently, the occupied spaces. The
ultraviolet bulb was dust-covered, potentially rendering it less
effective as an air disinfectant. Employees in the health clinics serve
patients with suspected or active TB at the clinics or at the homes of
the patients. Results from the environmental investigation indicate that
the ventilation systems in both buildings were recirculating with a
common return air plenum that could increase the potential risk of TB
transmission into other areas of the buildings. Recommendations were
offered to help the clinics improve their work environments and
potentially reduce the risk of TB transmission.
Copies are available from HETAB.
HETA 93-0770
February 1996
Purpose: To evaluate the effectiveness of the
ventilation systems for preventing tuberculosis (TB) transmission at
this outpatient TB clinic.
Keywords: SIC 8099 (Health and Allied
Services, Not Elsewhere Classified), tuberculosis, sputum induction,
ventilation system, outpatient clinic, health care workers, purified
protein derivative skin test, respirator.
Abstract: NIOSH investigators conducted an
evaluation at this outpatient TB clinic to assist the facility in
determining the best location for a future TB isolation room and to
determine the operational status of the ventilation systems serving the
areas of concern. Visual inspections were made of the general
ventilation system and the local exhaust ventilation (booth) used for
sputum inductions. The direction of air flow between rooms and adjacent
areas was determined using smoke tubes. Deficiencies identified during
the environmental evaluation that may increase the risk of TB
transmission included the lack of an isolation room, recirculation of
air throughout the facility, insufficient use of respiratory protection,
and problems with operation of the sputum collection booth.
Recommendations were made to correct the noted deficiencies and improve
the overall TB prevention program at this facility.
Copies are available from HETAB.
HETA 93-0772
July 1995
Purpose: To investigate the potential for
tuberculosis (TB) transmission in a neighborhood health center.
Keywords: SIC 8011 (Offices and Clinics of
Doctors of Medicine) and 8071 (Medical Laboratories), TB, skin testing,
ventilation.
Abstract: Because of concerns regarding the
potential for TB transmission in the facility, NIOSH was asked to
evaluate a neighborhood health center and make recommendations regarding
TB infection-control procedures. NIOSH representatives conducted a site
visit to review the tuberculin skin testing program, determine the
operational status of the ventilation system, and review ventilation
plans and specifications for the new addition to the building which was
under construction at the time of the survey. On the basis of a review
of the blueprints of the facility and a walk-through inspection, several
rooms in the new addition were chosen as future isolation rooms because
of their location within the facility and the ability to optimize the
ventilation rates of the rooms. NIOSH investigators found that although
the facility had implemented a comprehensive screening program for
employees, engineering control deficiencies and the lack of appropriate
respiratory protection may increase the risk of Mycobacterium
tuberculosis (M. tuberculosis) transmission in the
facility. Since most of the areas of the existing building recirculate
all room air, a potential to spread M. tuberculosis throughout
the facility existed whenever a client with active TB entered the
clinic. Additionally, the inappropriate use of a chemical fume hood for
the preparation of TB specimens may pose additional risks to employees.
Recommendations based on current Centers for Disease Control and
Prevention guidelines are offered in the report.
Copies are available from HETAB.
HETA 93-0780
March 1996
Purpose: To investigate the tuberculosis (TB)
prevention program, work practices, and engineering controls at this
hospital.
Keywords: SIC 8062 (General Medical and
Surgical Hospitals), TB, ventilation, skin test, Centers for Disease
Control and Prevention.
Abstract: NIOSH investigators conducted a
health hazard evaluation to review the TB prevention program, work
practices, and engineering controls within this hospital. The
investigation was prompted by concerns about several purified protein
derivative (PPD) skin test conversions among personnel in the Intensive
Care Unit (ICU). The TB infection-control program and administrative
procedures and policies were reviewed with hospital representatives.
Also, a limited ventilation evaluation was conducted in several regular
patient rooms, treatment rooms, and rooms designated for TB isolation.
The ventilation evaluation revealed a need to increase the air changes
per hour (ACH) in the ICU. Also, a need for improved respiratory
protection devices and a complete respirator program were needed. On the
basis of updated Centers for Disease Control and Prevention guidelines,
NIOSH investigators made specific recommendations about the employee
purified protein derivative (PPD) skin testing program, procedures for
handling infectious patients, use of respiratory protection, engineering
controls, and the bacteriology laboratory's procedures for processing
sputum samples.
Copies are available from HETAB.
HETA 93-0950
May 1997
Purpose: To investigate the effectiveness of
the tuberculosis (TB) control program at this medical center.
Keywords: SIC 8062 (General Medical and
Surgical Hospitals), TB, health care, hospital, infection control.
Abstract: NIOSH personnel conducted a health
hazard evaluation of the TB control program at this medical center.
Environmental evaluations were conducted at two hospitals. The
evaluations focused on areas where exposure to Mycobacterium
tuberculosis would most likely occur. Discussions were held with
representatives from Infection Control, Plant Services, Respiratory
Services, and the Laboratory. A limited ventilation evaluation was
conducted in selected areas, including measurements of exhaust airflow
and an assessment of airflow direction. A 1997 site visit included a
walk-through survey of the hospitals. Observations of smoke tube traces
were made to evaluate the direction of airflow in certain locations.
Discussions were held with the infection control specialist and a unit
nurse. A copy of the revised TB Control Policy and Procedures Manual was
obtained for review. Since the initial NIOSH visit in 1994, several
improvements occurred in the TB Control Program. These changes and NIOSH
recommendations for other improvements to the tuberculin skin test
screening program and ventilation systems are presented in the closeout
letter.
Copies are available from HETAB.
HETA 93-0845-2367, 93-0846-2386, 93-0751-2408, 93-0847-2384, and
93-0848-2399
November 1993 to March 1994
Purpose: To investigate the effectiveness of
ventilation systems in reducing tuberculosis (TB) transmission in health
care center facilities.
Keywords: SIC 8011 (Offices and Clinics of
Doctors of Medicine), TB, ventilation.
Abstract: NIOSH investigators conducted a
health hazard evaluation to assess the ventilation systems at several
health care centers, especially in regard to the suitability of these
systems for minimizing TB transmission. A visual inspection of the
ventilation systems, as well as a review of the original specifications
of the air-handling units, was completed for the centers. Smoke tubes
were used to determine pressure relationships between examination rooms
and corridors. A number of problems were observed with respect to the
operation and maintenance of the ventilation systems that could
potentially increase the risk of TB transmission in areas where TB
patients might be present. Heating, ventilating, and air-conditioning
units were operated in an automatic mode that resulted in no air being
supplied to examination rooms and laboratories when temperature
set-points were satisfied. The clinics had established a tuberculin skin
test screening program for clients but had no program for employees.
Recommendations to correct deficiencies in the ventilation system and TB
control program are offered in the full report.
Copies are available from NTIS, individually or on CD-ROM.
HETA 96-0192
August 1996
Purpose: To investigate engineering controls
planned for two county tuberculosis (TB) clinics.
Keywords: SIC 8093 (Specialty Outpatient
Facilities, Not Elsewhere Classified), TB, clinic, respirator.
Abstract: NIOSH representatives conducted a
health hazard evaluation to provide assistance in evaluating engineering
controls planned for two county TB clinics. To prevent TB transmission
from patients with unknown or unrecognized active TB, the county had
committed to renovating two existing medical facilities where TB clinics
are held. NIOSH visited the two facilities to determine if the proposed
control measures were necessary and adequate for preventing TB
transmission. NIOSH representatives met with personnel from the county's
environmental health, nursing, and engineering departments to discuss
ventilation requirements, use of germicidal ultraviolet radiation lamps,
tuberculin skin testing, and use of respirators and portable high
efficiency particulate air (HEPA) filtration units. Following this
meeting, NIOSH representatives toured the areas where the current TB
clinics were held as well as the area that was being renovated for
future use at the facility. At both facilities, routine TB skin testing
of clients was provided along with TB skin testing of suspect TB cases
and close contacts of persons known to have active TB. The medical staff
also provided X-rays and medical exams, and sputum samples were
sometimes collected from persons suspected of having active TB. Surgical
masks were provided to patients who may be infectious, and staff wore
NIOSH-approved disposable HEPA respirators when treating or examining
potentially infectious TB patients. On the basis of a facility tour and
discussions with county health department personnel, the NIOSH
investigators supported their efforts to consolidate TB-related
activities and to improve engineering controls at both facilities. NIOSH
recommendations are included in the full report.
Copies are available from HETAB.
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HETA 93-0365-2421
May 1994
Purpose: To investigate the administrative
and engineering control measures that are used to reduce potential
exposures to tuberculosis (TB) in an outpatient methadone maintenance
and detoxification center.
Keywords: SIC 8093 (Specialty Outpatient
Facilities, Not Elsewhere Classified), drug treatment center, methadone,
TB, tuberculin skin test (TST), ventilation.
Abstract: NIOSH investigators conducted a
health hazard evaluation at this outpatient facility to investigate
potential TB transmission due to contact with a client population at
high risk for TB. NIOSH investigators reviewed the facility's written
TST program and testing results and conducted informal interviews with
employees. A visual assessment of the ventilation and airflow patterns
was performed, and random measurements of the supply airflows were made.
The investigators found that of the 55 employees, three persons
converted to a positive skin test during their employment. As
information about the duration of employment was not fully available,
NIOSH investigators were unable to calculate the incidence of positive
skin tests among all employees. Investigators found that the ventilation
system within the center recirculated 100% of the air and is therefore
not an effective engineering control for reducing exposure to TB. It was
determined that a potential hazard existed for health care workers at
this facility who were exposed to clients with active TB.
Recommendations were made in the report to improve the ventilation
systems, use appropriate personal protective equipment, and improve the
TST program.
Copies are available from NTIS, individually or on CD-ROM.
[ Top of Page ]
HETA 92-0271-2349
September 1993
Purpose: To investigate the potential for
tuberculosis (TB) transmission at a parole office building.
Keywords: SIC 8322 (Individual and Family
Social Services), parole office, TB.
Abstract: NIOSH investigators conducted an
evaluation of the ventilation system in this parole office to assess air
distribution, outside air intake and dilution. NIOSH researchers
measured outside airflow and carbon dioxide
(CO2) concentrations, a surrogate indicator of
outside airflow into a building, and administered questionnaires to
employees. Outside air intake on the first floor (and possibly the third
floor) did not meet the American Society of Heating, Refrigerating, and
Air-Conditioning Engineers (ASHRAE) ventilation recommendations for
office space. Parole board employees may have had an added risk of TB
infection because (1) parolees are at increased risk for developing
active TB (all have been incarcerated, some are medically underserved,
and some are homeless) and (2) the ventilation system recirculated most
of the air in the facility, thereby permitting any infectious droplet
nuclei in the air to spread throughout the facility. Recommendations for
an employee TB screening program and improvements to the ventilation
system were provided in the full report.
Copies are available from NTIS, individually or on CD-ROM.
HETA 92-0345-2457
September 1994
Purpose: To investigate the potential for
occupational exposure to Mycobacterium tuberculosis (M.
tuberculosis) among social services employees.
Keywords: SIC 8093 (Specialty Outpatient
Facilities, Not Elsewhere Classified), tuberculosis (TB), tuberculin
skin test (TST).
Abstract: NIOSH investigators conducted a
health hazard evaluation to assess the potential for occupational
exposure to M. tuberculosis among county social services
employees. NIOSH conducted a TST program among these county employees.
One hundred forty-eight employees participated in the initial TST. In
the follow-up TST program, one person converted to a positive skin test
out of a total of 78 who completed the study. The low participation
rates for the study prevented drawing any definitive conclusions
regarding the risk of occupational transmission of TB among employees. A
recommendation was made to continue the skin testing program for those
workers who are potentially occupationally exposed to TB.
Copies are available from NTIS, individually or on CD-ROM.
HETA 93-0891-2430
June 1994
Purpose: To investigate the potential risk of
tuberculosis (TB) transmission to social service employees at three
sites.
Keywords: SIC 9441 (Administration of Social,
Human Resource and Income Maintenance Programs), TB, social service,
welfare, indoor air quality, indoor environmental quality.
Abstract: NIOSH representatives conducted a
health hazard evaluation of several social service offices to determine
(1) whether employees can reasonably anticipate risk of exposure to TB,
and (2) what engineering and administrative controls should be
recommended for social service settings. NIOSH investigators assessed
the ventilation system of the food stamp office and conducted a medical
evaluation of employees at all three sites. The environmental evaluation
indicated that the air handling units were not supplying sufficient
outdoor air (for dilution ventilation) on the day of measurement. The
medical evaluation included confidential interviews with 18 workers and
a review of the methods and results of a voluntary TB screening. Because
of sample size, the results of this screening effort may not represent
the actual prevalence of tuberculous infection. Recommendations for an
employee TB education and screening program for Division of Welfare
employees and for improvements to the ventilation system in the food
stamp office were provided in the full report.
Copies are available from NTIS, individually or on CD-ROM.
HETA 96-0233
September 26, 1996
Purpose: To investigate potential
transmission of tuberculosis (TB) from high-risk clients to employees
working in housing program administrative offices.
Keywords: SIC 9531 (Administration of Housing
Programs), TB, engineering controls.
Abstract: NIOSH investigators met with staff
and management of this city housing program to discuss potential
transmission of TB from high-risk clients to employees. NIOSH was asked
to provide advice about procedures and engineering controls to prevent
occupational transmission of TB. NIOSH representatives did not collect
specific data about the risk of TB infection incurred from relatively
brief visits to the offices by applicants seeking housing. However, many
of the applicants appear to fall within high-risk categories for active
TB disease. Therefore, it is reasonable to take measures to reduce the
chances of TB transmission. Recommendations for reducing exposure risk
through employee education and early identification of persons with
symptoms of active disease were provided in the closeout report.
Copies are available from HETAB.
[ Top of Page ]
HETA 92-0171-2255
September 1992
Purpose: To investigate the potential for
tuberculosis (TB) transmission resulting from autopsies of persons with
TB at time of death.
Keywords: SIC 9199 (General Government Not
Elsewhere Classified), autopsy, morgue, TB, germicidal ultraviolet (UV)
radiation, ventilation.
Abstract: NIOSH investigators conducted an
evaluation at this medical examiner's office regarding the potential for
TB transmission resulting from autopsies conducted on persons who had
active multidrug-resistant TB at the time of their death. Investigators
evaluated the ventilation systems serving the morgue and office areas
and observed work practices and use of personal protective equipment
during an autopsy. A fog-generating device and ventilation smoke tubes
used to visually assess airflow patterns demonstrated the potential for
air movement out of the morgue and into surrounding areas. Thus,
researchers concluded that a potential hazard existed for workers
exposed to aerosols containing Mycobacterium tuberculosis
generated during autopsy. The use of high-speed tools and other aerosol
generating procedures that encounter collections of TB-infected material
presents a potentially high-risk exposure situation. Recommendations
were made in the report to correct existing ventilation deficiencies,
including isolation of the morgue ventilation system, use of personal
protective equipment, safe use of germicidal UV lamps, and the provision
of separate clean and dirty change areas for morgue personnel.
Copies are available from NTIS, individually or on CD-ROM.
HETA 96-0019-2666
December 1997
Purpose: To investigate airborne particulates
generated by a pneumatic reciprocating saw equipped with local exhaust
ventilation (LEV).
Keywords: SIC 9221 (Police Protection),
tuberculosis, human immunodeficiency virus, coroner, bloodborne
pathogen, noise, cranial saws.
Abstract: NIOSH investigators conducted a
health hazard evaluation in this coroner's office to evaluate a
pneumatic reciprocating saw equipped with LEV used for making cranial
openings during forensic autopsies and examinations. The objective of
the NIOSH evaluation was to determine if the alternative reciprocating
saw generated less tissue and bone fragment aerosol that could
potentially enter the breathing zone of the operating forensic
technician. Differences in peak concentrations of airborne particulates
measured during autopsies with and without the aid of LEV, indicate that
LEV significantly reduced the aerosols produced by the reciprocating
saws. No short-term, high concentrations of particulates were observed
during autopsies utilizing the LEV system. LEV applied at the cutting
surface of reciprocating surgical saws can be an effective tool to
reduce the risk of occupational exposure to blood, bone, and tissue
aerosol fragments during autopsies. However, the vacuum system should be
mechanically integrated with the activation of the reciprocating saw,
eliminating the possibility of operator error.
Copies are available from NTIS.
[ Top of Page ]
HETA 92-282-2297
March 1993
Purpose: To investigate medical department
staff exposure to Mycobacterium tuberculosis (M.
tuberculosis) at a correctional facility.
Keywords: SIC 9223 (Correctional
Institutions), prisons, tuberculosis (TB).
Abstract: NIOSH investigators conducted a
health hazard evaluation at this correctional institution to determine
whether staff in the Medical Department were potentially exposed to
M. tuberculosis from an inmate diagnosed with active TB. NIOSH
investigators met with representatives of labor and management to
collect information regarding the patient's illness, isolation, and
treatment, and the TB screening programs provided by the correctional
institution. The heating, ventilating, and air-conditioning system in
the Medical Department was evaluated to identify possible deficiencies
that could contribute to the transmission of M. tuberculosis.
The majority of air in the building was recirculated. Because of this,
there was a potential for M. tuberculosis from the Medical
Department to be transmitted throughout that department as well as the
administrative offices. Other ventilation deficiencies that may increase
the potential for M. tuberculosis transmission included
insufficient total and outside air supply, and incorrect pressure
relationships between rooms and adjacent corridors. Recommendations to
reduce the potential for M. tuberculosis transmission,
including medical screening and improved ventilation, were provided in
the report.
Copies are available from NTIS, individually or on CD-ROM.
HETA 93-0364
May 1993
Purpose: To evaluate the tuberculosis (TB)
control policy at this youth detention center.
Keywords: SIC (9223 Correctional
Institutions), TB, correctional facility, detention, youth, tuberculin
skin test.
Abstract: NIOSH investigators reviewed the TB
control policy at this youth detention center. The detention center's
policy required TB skin testing for all employees at time of employment
and annually thereafter. Review of the medical department TB records
revealed that the records were incomplete. Test results and follow-up
procedures were recorded on a number of different forms located in
different areas. In addition, many of the negative skin tests were
recorded in the records as "negative," rather than as the number of
millimeters of induration. The only skin test conversion documented in
the records occurred in 1982. There had been no known active TB cases
among residents or staff at the detention center. Recommendations were
made in the report to develop a written TB control program in accordance
with the Centers for Disease Control and Prevention guidelines, improve
record keeping, and enhance TB educational efforts.
Copies are available from HETAB.
HETA 93-0748
January 1996
Purpose: To evaluate the ventilation systems
serving this county jail.
Keywords: SIC (9223 Correctional
Institutions), tuberculosis (TB), correctional facility, jail,
ventilation.
Abstract: NIOSH investigators conducted a
ventilation system evaluation to assess the potential for dissemination
of airborne Mycobacterium tuberculosis (M.
tuberculosis) at this county jail. The ventilation system
evaluation consisted of a review of mechanical plans, discussions with
persons responsible for maintenance of the heating, ventilation, and
air-conditioning (HVAC) systems, and a visual assessment of air flow
patterns (using chemical smoke) in the cell block areas. HVACs of
various designs were observed throughout the jail. Many of the systems
or components were inoperable. In some areas, natural ventilation (open
windows) and ceiling fans were used to enhance the mechanical
ventilation. In the cell block area used to isolate suspected TB
infected inmates, the exhaust and supply duct work to the individual
cells and associated corridors were disconnected from the central HVAC
system to minimize the recirculation of contaminated air. However, this
also resulted in no outdoor air being delivered to the occupied spaces.
A floor fan was positioned to blow air across the face of the isolation
cells, and another was positioned perpendicular to the first, exhausting
entrained air out of an open door. Based on the location of the guard's
desk, air from the cells that was not exhausted was directed at the
guard. Recommendations were made to correct the ventilation deficiencies
and improve directional air flow, dilution, and removal of contaminated
air. Additional recommendations were made to improve the overall TB
control program (screening of employees, education and training, use of
respiratory protection, etc.).
Copies are available from HETAB.
HETA 94-0238-2484
February 1995
Purpose: To investigate the potential for
tuberculosis (TB) transmission among law enforcement personnel who have
contact with prisoners.
Keywords: SIC 9221 (Police Protection), TB,
tuberculin skin test (TST), correctional facility, indoor environmental
quality, ventilation.
Abstract: NIOSH representatives conducted an
environmental and medical evaluation at this correctional facility.
Confidential medical interviews were conducted with five of the seven
employees who were reported to have newly reactive TSTs. The on-site
occupational health nurse was interviewed, and medical records and the
employee TST program were reviewed. The heating, ventilating, and
air-conditioning (HVAC) units that served the offices and cellblocks
were evaluated to determine their effectiveness in reducing the airborne
transmission of infectious agents. The medical evaluation found that six
(9%) of the employees who had received a TST had a positive response.
The available TST data were not sufficient to assess the prevalence of
TB infection or the extent of work-related risk of TB among employees.
The physical evaluation of the ventilation system indicated that it was
potentially inadequate, and some of the HVAC units serving the office
areas had signs of deficient general maintenance. NIOSH investigators
determined that the employees may have had an increased risk of
occupationally acquired TB infection because they are in contact with
prisoners, a group considered to be at high risk for developing active
TB. Recommendations for an employee TB education and surveillance
program, and for improving the work environment, especially the
ventilation systems, were presented in the full report.
Copies are available from NTIS, individually or on CD-ROM.
HETA 95-0024-2518
August 1995
Purpose: To investigate the potential for
tuberculosis (TB) transmission among law enforcement personnel who have
contact with prisoners.
Keywords: SIC 9221 (Police Protection), TB,
tuberculin skin test (TST), correctional facility, prisoners, indoor
environmental quality ventilation.
Abstract: NIOSH investigators conducted a
health hazard evaluation at this correctional facility to evaluate the
potential for TB transmission among personnel who have contact with
prisoners. Confidential medical interviews were conducted with employees
who were reported to have newly reactive TSTs, and medical records and
the employee TST program were reviewed. A walk-through inspection of the
facility was conducted, and ventilation measurements were made to
evaluate the potential for dissemination of droplet nuclei. The
environmental evaluation revealed deficiencies in the amount of outdoor
air supplied to the cell block area and in the delivery of supply air to
the cell block and office areas. These deficiencies minimize the
contribution of ventilation and directional airflow in diluting or
removing contaminated air. The available TST data were not sufficient to
assess the prevalence of TB infection or the occupational risk of TB
transmission among employees. However, employees have contact with
prisoners, a group considered to be at high risk for developing active
TB. Recommendations for improving the TST surveillance program and
environmental controls were provided in the report.
Copies are available from NTIS, individually or on CD-ROM.
[ Top of Page ]
HETA 92-0377-2625
January 1997
Purpose: To investigate the transmission of
TB among employees working in laboratories where clinical specimens are
processed.
Keywords: SIC 8071 (Medical Laboratories),
TB, laboratory-acquired infections, skin testing, ventilation.
Abstract: NIOSH investigators conducted a
health hazard evaluation at this medical laboratory regarding the
transmission of tuberculosis among employees working in laboratories
where clinical specimens were processed. Workers handling viable
Mycobacterium tuberculosis (M. tuberculosis) specimens may
be at increased risk of becoming infected while performing their jobs.
According to employee recall, 23% of persons employed in the labs
converted to a positive tuberculin skin test over an 8-year period.
However, limitations of the study made it difficult to draw any
definitive conclusions regarding the risk of occupational transmission
of M. tuberculosis among the employees at these laboratories.
It is imperative that the laboratory follows current Centers for Disease
Control and Prevention guidelines for handling M. tuberculosis
samples. Recommendations were offered in the full report to reduce the
risk of occupational transmission of TB and to improve the working
environment for the employees.
Copies are available from NTIS.
HETA 93-0282-2303
April 1993
Purpose: To investigate possible exposures to
ultraviolet (UV) radiation in a hospital microbiology laboratory.
Keywords: SIC 8071 (Medical Laboratories),
tuberculosis (TB), UV radiation.
Abstract: NIOSH investigators conducted a
health hazard evaluation to evaluate possible exposures to ultraviolet
radiation in a hospital microbiology laboratory. Exposure to UV
radiation was from germicidal UV lamps present in a Class II Type A
biological safety cabinet (BSC). Ultraviolet radiation levels varied
widely, depending on the location of measurement. At eye level directly
in front of the BSC, irradiance was approximately 4.0 microwatts per
square centimeter (µW/cm2); this equates
to a NIOSH/ACGIH permissible exposure time of 25 minutes for unprotected
workers. The UV irradiance at an adjacent computer terminal (eye level)
was 0.8 µW/cm2 (permissible exposure
time of 120 minutes). Exposure to UV radiation was determined to present
a potential health hazard for employees working near the BSC.
Recommendations to minimize employee exposures to UV are included in the
report.
Copies are available from NTIS, individually or on CD-ROM.
HETA 93-0769-2489
February 1995
Purpose: To investigate the potential for
Mycobacterium tuberculosis (M. tuberculosis)
transmission in this mycobacteriology laboratory.
Keywords: SIC 8071 (Medical Laboratories),
tuberculosis (TB), laboratory-acquired infections, skin testing,
ventilation.
Abstract: NIOSH investigators conducted an
evaluation to assess the control measures used to prevent M.
tuberculosis transmission in this mycobacteriology laboratory. A
walk-through survey of the laboratory and a visual assessment of its
heating, ventilating, and air conditioning system was conducted at the
time of the site visit. Additionally, the employee tuberculin skin
testing (TST) program was reviewed, and a microbiologist was observed
during the processing of samples to evaluate work practices and
procedures. The visual assessment of the ventilation system and
evaluation of the design of the laboratory revealed that the potential
exists for dissemination of M. tuberculosis to other parts of
the laboratory. The facility did not have a written TST surveillance
program and, at the time of the evaluation, no central file was used for
tracking TST results. A respiratory protection program meeting
Occupational Safety and Health Administration requirements had not been
implemented for the laboratory. A potential health hazard existed for
workers who may be exposed to aerosols generated in the laboratory, due
to deficiencies in the design of the laboratory and operation of the
ventilation system and the lack of appropriate respiratory protection.
Since the TB laboratory is not properly sealed, the possibility existed
that M. tuberculosis bacilli could be disseminated to other
areas of the laboratory. Recommendations were presented in this report
to correct deficiencies identified during the evaluation and to meet the
minimum guidelines recommended by Centers for Disease Control and
Prevention and National Institutes of Health.
Copies are available from NTIS, individually or on CD-ROM.
HETA 98-0296
November 1998
Purpose: To investigate the tuberculosis (TB)
transmission controls in place in a mycobacteriology laboratory.
Keywords: SIC 8071 (Medical Laboratories),
TB, laboratory-acquired infections, ventilation.
Abstract: An evaluation of this
mycobacteriology laboratory was conducted to assess the TB controls in
place at the facility. Measurements were taken for airflow, air static
pressure, and particle counts to quantify containment parameters.
Measurements were also made of the energy produced by ultraviolet
germicidal irradiation (UVGI) lamps located in the bacteriology
laboratory, the biology safety cabinet, and the Biosafety Level 3
containment laboratory. NIOSH investigators found that the use of
physical barriers alone could not prevent the migration of contaminants
from one area to another. NIOSH recommended the use of general
ventilation to create pressure differentials between activity zones to
minimize opportunities for contaminant escape when doors are opened.
Additional recommendations concerning the use of UVGI and respiratory
protection are made in the report, along with recommendations for
preventative maintenance of the ventilation system and laboratory
hoods.
Copies are available from HETAB.
[ Top of Page ]
HETA 92-0320-2357
October 1993
Purpose: To investigate control measures used
to prevent tuberculosis (TB) transmission at a social service facility
and homeless center.
Keywords: SIC 8399 (Social Services, Not
Elsewhere Classified), TB, germicidal ultraviolet (GUV) radiation, skin
testing, ventilation.
Abstract: NIOSH investigators conducted a
health hazard evaluation at a social services facility that provides
counseling, medical care, and housing assistance for homeless clients.
NIOSH was asked to investigate the operational status of a ventilation
system and GUV lamps in preventing TB transmission, along with assessing
the potential for Mycobacterium tuberculosis (M.
tuberculosis) exposures from the homeless center located in the
same building. At this facility, investigators reviewed the written
tuberculin screening program and results of the client and employee
tuberculin skin tests (TST). A visual assessment of the ventilation
system and airflow patterns was made, and measurements of the supply and
exhaust airflows were obtained and compared to the design
specifications. The majority of the air in the facility is recirculated
and therefore, there is potential for airborne M. tuberculosis
to be transmitted throughout the facility. Other deficiencies identified
that may increase the potential for TB transmission included
insufficient outside air supply and inconsistent client screening
techniques. At the homeless center, a visual assessment of the
ventilation system was performed and results of the employee tuberculin
screening were reviewed. The only mechanical ventilation systems are the
exhaust fans, in the bathrooms, gymnasium, and kitchen and the cool-air
recirculating system in the cafeteria. Since the center relies on
exhaust fans and natural ventilation for dilution and removal of air
contaminants, a potential for TB exposures exists whenever a client with
active TB attends the center. A potential health hazard existed for
workers exposed to clients who have active TB in both the social
services facility and the homeless center. The report, contained
recommendations to reduce the potential for TB transmission, including
improved TST screening and ventilation at each facility.
Copies are available from NTIS, individually or on CD-ROM.
HETA 93-0771-2437
July 1994
Purpose: To investigate the potential for
Mycobacterium tuberculosis (M. tuberculosis)
transmission in a residential care facility.
Keywords: SIC 8361 (Social Services,
Residential Care), tuberculosis (TB), human immunodeficiency virus
(HIV)-infection, skin testing, ventilation.
Abstract: NIOSH investigators conducted a
health hazard evaluation at this residential care facility to evaluate
the potential for M. tuberculosis transmission in the
residential facility duplexes that were to provide housing for homeless
HIV- infected persons. On the basis of a review of the plans of the
facility and a walk-through inspection, a room was selected that could
be used to house individuals with suspected infectious TB. The room was
recommended on the basis of its remote location within the complex and
the ability to optimize ventilation rates. Further evaluation was
recommended to ensure that short-circuiting of the supply and exhaust
airflows would not occur. Investigators found that a potential health
hazard existed due to deficiencies in the ventilation system and the
lack of appropriate respiratory protection. At the time of the
investigation, no guidelines addressing M. tuberculosis
exposures existed in residential facilities for HIV-infected
individuals; however, many of the guidelines pertaining to health care
facilities are applicable for this type of setting. The report contained
recommendations regarding administrative and engineering controls and
the use of appropriate respiratory protection to prevent M.
tuberculosis transmission in the facility, as well as during the
transport of potentially infectious individuals.
Copies are available from NTIS, individually or on CD-ROM.
[ Top of Page ]
HETA 93-0859
August 1995
Purpose: To investigate the potential for
exposure to tuberculosis (TB) during inspection of nonhuman
primates.
Keywords: SIC 9512 (Land, Mineral, Wildlife,
and Forest Conservation), TB, nonhuman primates, zoonotic pathogens.
Abstract: NIOSH and the Centers for Disease
Control and Prevention investigators made a site visit to an airport to
observe procedures used during inspection of two shipments of imported
nonhuman primates. NIOSH investigators observed and conducted an
interview with an animal inspector. The investigators observed that the
inspector's actual contact with the animals was very brief during a
routine inspection. "Contact" was defined as being within 5 feet of an
animal. The inspections were done on the airport tarmac. Based on
observations from this evaluation, inspectors have the potential for
exposures to zoonotic pathogens including Mycobacterium
tuberculosis during inspection of nonhuman primate shipments. This
risk is minimized in that inspectors are not required to handle the
animals or cages during routine inspection. Considering that inspectors
do not have direct physical contact with the animals or cages during
routine inspection, the most probable route of exposure for zoonotic
pathogens during inspection would be respiratory exposure. On the basis
of the brief nature of the work task and the variable nature of the work
locations and environments, engineering controls such as exhaust
ventilation would be difficult to use as a control for respiratory
exposures. Personal protective equipment was noted to be a more suitable
control alternative.
Copies are available from HETAB.
HETA 95-0031-2601
October 1996
Purpose: To investigate the effectiveness of
a supplemental high efficiency particulate air (HEPA) filtration system
in reducing potential tuberculosis (TB) transmission.
Keywords: SIC 4119 (Local Passenger
Transportation, Not Elsewhere Classified), TB, ambulance, emergency
medical services, Emergency medical service (EMS), health care, HEPA
filtration.
Abstract: NIOSH investigators conducted a
health hazard evaluation at this medical center to evaluate a
supplemental HEPA filtration system installed in a new ambulance. NIOSH
investigators conducted a field evaluation of particle clearance in an
ambulance equipped with a supplemental HEPA filtration system. A similar
ambulance without the HEPA filtration system was also evaluated for
comparison. The results indicated that the ambulance with the
supplemental HEPA filtration system cleared particles faster than the
ambulance without the supplemental system, when tested under similar
conditions. This evaluation also showed that particle clearance could be
improved by the use of the rear vent fan (when positioned on the "high"
setting) in conjunction with the provision of outside air through the
vehicle's main heating, ventilating, and air-conditioning systems. For
vehicles that do not have supplemental HEPA filtration systems, using
the vent fan and providing outside air through the vehicle's main HVAC
system improves aerosol clearance and thus reduces the potential risk of
TB transmission. Recommendations concerning the use of respiratory
protection by workers during transport of known or suspected infectious
TB patients, and for the performance of regular preventive maintenance
and leak testing of the HEPA unit were included in the report.
Copies are available from NTIS, individually or on CD-ROM.
HETA 95-0328-2630
March 1997
Purpose: To investigate the ventilation
system at this textile sewing plant.
Keywords: SIC 2361 (Girls', Children's, and
Infants' Dresses, Blouses, and Shirts), tuberculosis (TB), sewing,
ventilation, tracer gas, sulfur hexafluoride.
Abstract: NIOSH researchers conducted an
evaluation of this sewing plant to evaluate the ventilation system after
one employee was diagnosed with TB and a large number of others tested
positive on tuberculin skin tests. NIOSH investigators performed an
initial evaluation to measure airflow rates and assess air movement
within the plant. An in-depth ventilation assessment was later made to
document conditions that likely occurred during the period that the
employee with TB was infectious. This involved a tracer gas evaluation
to quantify the extent and speed of contaminant dispersion and
contaminant removal rate. When the tracer gas was released in the middle
of the plant, it was detected at the furthest points in the production
area (approximately 100 feet away) within 11 minutes. The tracer gas was
also detected in the engineering and main office areas, the cafeteria,
and the conference room. The NIOSH evaluation determined that
ventilation conditions were favorable for TB transmission based on a low
air change rate and excellent air mixing within the plant. Thus, TB
bacteria would have spread quickly and uniformly throughout the plant
and remain suspended for hours before being removed from the air. Other
factors that may have influenced TB transmission include prolonged
infectiousness of the individual, virulence of the organism, and TB
exposure outside the workplace. Recommendations for improving general
ventilation were made in the report.
Copies are available from NTIS.
HETA 98-0027-2709
March 1998
Purpose: To investigate potential
occupational exposures to Mycobacterium tuberculosis (M.
tuberculosis) at a biomedical waste disposal facility.
Keywords: SIC 4953 (Refuse Systems),
tuberculosis (TB), biomedical waste.
Abstract: NIOSH investigators conducted a
health hazard evaluation to evaluate potential occupational exposures to
M. tuberculosis at this medical waste treatment facility. The
request concerned exposures to M. tuberculosis from the
processing of infectious waste due to a recent outbreak of TB among
employees at the facility. NIOSH investigators conducted a site visit to
(1) observe work practices, (2) collect information about the operation
and maintenance of the process equipment, and (3) discuss company
policies regarding the use of personal protective equipment, training
programs, and accident/injury and spill response. NIOSH identified
several factors in the facility that could contribute to employee
exposures to pathogens potentially present in the medical waste. These
included the use of a process that creates the potential for
aerosolization of the products contained in the waste prior to
deactivation; deficiencies in the design of the facility; the policies
in place at the facility; the design and operation of the equipment used
at the facility (including personal protective equipment); and
misunderstandings among employees about operations, personal protective
equipment, medical issues, and policies and procedures. Recommendations
to help prevent exposures to M. tuberculosis and bloodborne pathogens
are provided in the report.
Copies are available from NTIS.
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