Outbreaks of Respiratory Illness among Employees in Large
Office Buildings -- Tennessee, District of Columbia
Recurring outbreaks of respiratory illness among office workers
have led to epidemiologic and environmental investigations and to
relocation of some or all occupants of the affected office areas.
Outbreaks in two cities are summarized below.
Knoxville, Tennessee: An outbreak of febrile illness began
during
the afternoon and evening of September 21, 1981. About 40% of the
325
office workers in a seven-story building met the case definition of
at
least three symptoms (headaches, muscle aches, fever, chills,
cough,
or wheezing) and a time of onset after 11 a.m. (use of this time of
onset helped to exclude individuals with preexisting respiratory
conditions that were unrelated to exposures in the building). In
most
affected individuals, these symptoms subsided by the following
morning. Subsequent outbreaks of febrile illness occurred in this
same building on October 13 and October 15. After the latter
outbreak, building occupants were moved to other office facilities.
In each outbreak, a temporal relationship was observed between
starting the heating, ventilation, and air-conditioning (HVAC)
system
and the onset of symptoms. The HVAC system in this building
contained
two air washers (components of an air-handler unit that emit a
water
spray) and was contaminated with bacteria, fungi, protozoa,
nematodes,
and mites. No single microbial agent could be established as
responsible for the outbreaks. The HVAC system was the mode of
transmission for the organisms. The building remains vacant.
Washington, D.C.: In late January 1982, a persistent,
influenza-like illness was reported among occupants of a large
office
suite on one floor of an eight-story building. Twelve of 41
employees
working in the suite met the case definition of at least two of the
following symptoms: headache, muscle aches, chest tightness,
feverishness, chills, or nausea occurring on consecutive work days,
including the last work day (Friday), with relief on weekends.
Tests
of the carbon-monoxide-diffusing capacity of affected individuals
showed that individuals with two or more symptoms had lower
single-breath, carbon-monoxide-diffusing capacities than did
controls.
The suite was located directly beneath the kitchen of a
cafeteria
and had been subjected to a series of "floods" from drainage lines,
including a drain from the cafeteria dishwasher. Numerous
microorganisms, including Acanthamoeba polyphaga and
Thermoactinomyces
vulgaris, were isolated from the office and the HVAC system.
However,
attempts through serologic testing to link these agents
specifically
with illness in individuals produced inconclusive results.
Epidemiologic evidence suggested that environmental contaminants
present in the water drainage were associated with illness. All
workers were removed from the affected office; the office was
completely refurbished and is presently being reoccupied. There
has
been no recurrence of illness.
Reported by Div of Respiratory Disease Studies, National Institute
for
Occupational Safety and Health, CDC.
Editorial Note
Editorial Note: Outbreaks of hypersensitivity pneumonitis (HP),
humidifier fever, and similar syndromes among office workers have
been
described since 1970 (1,2). Symptoms include headache, fatigue,
muscle aches, chills, and fever. Manifestations of pulmonary
disease,
such as chest tightness, coughing, and wheezing, were also
observed.
These outbreaks have been attributed to thermophilic actinomycetes,
nonpathogenic amoeba, several fungi, and endotoxins (3-6). Sources
of
microbial contamination included humidifiers, air washers, and
contaminated filters in air-handling units.
Since October 1981, the National Institute for Occupational
Safety
and Health has conducted environmental studies in six large
multistory
office buildings in which HP-like syndromes were reported or were
alleged to occur, including those reported here (7). Results of
these
studies suggest that moisture incursion into occupied spaces and
into
HVAC system components may have been common to these outbreaks.
Engineering measures thought to prevent the occurrence of such
outbreaks are straightforward, feasible, and inexpensive. They
include: (1) promptly and permanently repairing all external and
internal leaks; (2) maintaining relative humidity below 70% in
occupied spaces and in low-air-velocity plenums (at higher levels
of
humidity, the germination and proliferation of fungal spores is
enhanced(8,9)); (3) preventing the accumulation of stagnant water
under cooling-deck coils of air-handling units through proper
inclination and continuous drainage of drain pans; (4) using steam,
rather than recirculated water, as a water source for humidifiers
in
HVAC systems; however, such steam sources should not be
contaminated
with volatile amines; (5) replacing filters in air-handling units
at
regular intervals (these should have at least a moderate efficiency
rating (50% or more) as measured by the atmospheric-dust spot test
(10,11) and should be of the extended-surface type; prefilters
(e.g.,
roll type) should be used before air passage over the
higher-efficiency filters); (6) discarding, rather than
disinfecting,
carpets, upholstery, ceiling tiles, and other porous furnishings
that
are grossly contaminated; (7) providing outdoor air into
ventilation
systems at minimum rates per occupant of at least 20 cubic feet per
minute in areas where occupants are smoking and at least 5 cubic
feet
per minute in nonsmoking areas (12). These activities should be
considered in on-going preventive-maintenance programs.
References
Arnow PM, Fink JN, Schlueter DP, et al. Early detection of
hypersensitivity pneumonitis in office workers. Am J Med
1978;64:236-42.
Kreiss K, Hodgson M. Building associated epidemics. In: J
Walsh,
C Dudney, E Copenhaver, eds. Indoor air pollution. Boca
Raton,
Florida: CRC Press, 1984:87-106.
Banaszak EF, Thiede WH, Fink JN. Hypersensitivity pneumonitis
due
to contamination of an air conditioner. New Engl J Med
1970;283:271-6.
Edwards JH. Microbial and immunological investigations and
remedial action after an outbreak of humidifier fever. Br J
Ind
Med 1980;37:55-62.
Bernstein RS, Sorenson WG, Garabrant D, Reaux C, Treitman RD.
Exposures to respirable, airborne Penicillium from a
contaminated
ventilation system: clinical, environmental and epidemiological
aspects. Am Ind Hyg Assoc J 1983;44:161-9.
Rylander R, Haglind P, Lundholm M, Mattsby I, Stenqvist K.
Humidifier fever and endotoxin exposure. Clin Allergy
1978;8:511-6.
Morey PR, Hodgson MJ, Sorenson WG, Kullman GK, Rhodes WW,
Visvesvara GS. Environmental studies in moldy office
buildings:
biological agents, sources and preventive measures. Ann Am
Conf
Gov Ind Hyg (in press).
Block SS. Humidity requirements for mold growth. Appl
Microbiol
1953;1:287-93.
Brundrett GW, Onions AHS. Moulds in the home. J Consum Stud
Hom
Econ 1980;4:311-21.
Barnstable D. Basic considerations for selecting air filters.
Plant Engin 1981;45:145-7.
American Society of Heating, Refrigerating, and
Air-conditioning
Engineers. Method of testing air-cleaning devices used in
general
ventilation for removing particulate matter. Atlanta, Georgia:
ASHRAE, 1976. ASHRAE Standard 52-76.
American Society of Heating, Refrigerating, and
Air-conditioning
Engineers. Ventilation for acceptable indoor air quality.
Atlanta, Georgia: ASHRAE, 1981. ASHRAE Standard 62-1981.
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