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The term "sick building syndrome" (SBS) is
used to describe situations in which building occupants
experience acute health and comfort effects that appear to
be linked to time spent in a building, but no specific
illness or cause can be identified. The complaints may be
localized in a particular room or zone, or may be widespread
throughout the building. In contrast, the term "building
related illness" (BRI) is used when symptoms of diagnosable
illness are identified and can be attributed directly to
airborne building contaminants.
A 1984 World Health Organization Committee
report suggested that up to 30 percent of new and remodeled
buildings worldwide may be the subject of excessive
complaints related to indoor air quality (IAQ). Often this
condition is temporary, but some buildings have long-term
problems. Frequently, problems result when a building is
operated or maintained in a manner that is inconsistent with
its original design or prescribed operating procedures.
Sometimes indoor air problems are a result of poor building
design or occupant activities.
Indicators of SBS include:
- Building occupants complain of
symptoms associated with acute discomfort, e.g.,
headache; eye, nose, or throat irritation; dry
cough; dry or itchy skin; dizziness and nausea;
difficulty in concentrating; fatigue; and
sensitivity to odors.
- The cause of the symptoms is not
known.
- Most of the complainants report
relief soon after leaving the building.
Indicators of BRI include:
- Building occupants complain of
symptoms such as cough; chest tightness; fever,
chills; and muscle aches
- The symptoms can be clinically
defined and have clearly identifiable causes.
- Complainants may require
prolonged recovery times after leaving the building.
It is important to note that complaints
may result from other causes. These may include an illness
contracted outside the building, acute sensitivity (e.g.,
allergies), job related stress or dissatisfaction, and other
psychosocial factors. Nevertheless, studies show that
symptoms may be caused or exacerbated by indoor air quality
problems.
The following have been cited causes of or
contributing factors to sick building syndrome:
Inadequate ventilation:
In the early and mid 1900's, building ventilation
standards called for approximately 15 cubic feet per
minute (cfm) of outside air for each building occupant,
primarily to dilute and remove body odors. As a result
of the 1973 oil embargo, however, national energy
conservation measures called for a reduction in the
amount of outdoor air provided for ventilation to 5 cfm
per occupant. In many cases these reduced outdoor air
ventilation rates were found to be inadequate to
maintain the health and comfort of building occupants.
Inadequate ventilation, which may also occur if heating,
ventilating, and air conditioning (HVAC) systems do not
effectively distribute air to people in the building, is
thought to be an important factor in SBS. In an effort
to achieve acceptable IAQ while minimizing energy
consumption, the American Society of Heating,
Refrigerating and Air-Conditioning Engineers (ASHRAE)
recently revised its ventilation standard to provide a
minimum of 15 cfm of outdoor air per person (20
cfm/person in office spaces). Up to 60 cfm/person may be
required in some spaces (such as smoking lounges)
depending on the activities that normally occur in that
space (see ASHRAE Standard 62-1989).
Chemical contaminants from indoor sources:
Most indoor air pollution
comes from sources inside the building. For example,
adhesives, carpeting, upholstery, manufactured wood
products, copy machines, pesticides, and cleaning agents
may emit volatile organic compounds (VOCs), including
formaldehyde. Environmental tobacco smoke contributes
high levels of VOCs, other toxic compounds, and
respirable particulate matter. Research shows that some
VOCs can cause chronic and acute health effects at high
concentrations, and some are known carcinogens. Low to
moderate levels of multiple VOCs may also produce acute
reactions. Combustion products such as carbon monoxide,
nitrogen dioxide, as well as respirable particles, can
come from unvented kerosene and gas space heaters,
woodstoves, fireplaces and gas stoves. For more
information, see
VOCs;
Carbon Monoxide;
Formaldehyde;
Nitrogen
Dioxide;
Respirable Particles.
Chemical contaminants from outdoor
sources:
The outdoor air that enters a building can be a source
of indoor air pollution. For example, pollutants from
motor vehicle exhausts; plumbing vents, and building
exhausts (e.g., bathrooms and kitchens) can enter the
building through poorly located air intake vents,
windows, and other openings. In addition, combustion
products can enter a building from a nearby garage.
Biological contaminants:
Bacteria, molds, pollen, and viruses are types of
biological contaminants. These contaminants may breed in
stagnant water that has accumulated in ducts,
humidifiers and drain pans, or where water has collected
on ceiling tiles, carpeting, or insulation. Sometimes
insects or bird droppings can be a source of biological
contaminants. Physical symptoms related to biological
contamination include cough, chest tightness, fever,
chills, muscle aches, and allergic responses such as
mucous membrane irritation and upper respiratory
congestion. One indoor bacterium, Legionella, has caused
both Legionnaire's Disease and Pontiac Fever. For more
information, see
Biologicals and
Mold.
These elements may act in combination,
and may supplement other complaints such as inadequate
temperature, humidity, or lighting. Even after a
building investigation, however, the specific causes of
the complaints may remain unknown.
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A Word
About Radon and Asbestos...
SBS and BRI are
associated with acute or immediate health
problems; radon and asbestos cause long-term
diseases which occur years after exposure, and
are therefore not considered to be among the
causes of sick buildings. This is not to say
that the latter are not serious health risks;
both should be included in any comprehensive
evaluation of a building's IAQ. See
www.epa.gov/radon and
www.epa.gov/asbestos |
The goal of a building investigation is to
identify and solve indoor air quality complaints in a way
that prevents them from recurring and which avoids the
creation of other problems. To achieve this goal, it is
necessary for the investigator(s) to discover whether a
complaint is actually related to indoor air quality,
identify the cause of the complaint, and determine the most
appropriate corrective actions.
An indoor air quality investigation
procedure is best
characterized as a cycle of information gathering,
hypothesis formation, and hypothesis testing. It
generally begins with a walkthrough inspection of the
problem area to provide information about the four basic
factors that influence indoor air quality:
- the occupants
- the HVAC system
- possible pollutant pathways
- possible contaminant sources.
Preparation for a walkthrough
should include documenting easily obtainable information
about the history of the building and of the complaints;
identifying known HVAC zones and complaint areas;
notifying occupants of the upcoming investigation; and,
identifying key individuals needed for information and
access. The walkthrough itself entails visual inspection
of critical building areas and consultation with
occupants and staff.
The initial walkthrough
should allow the investigator to develop some possible
explanations for the complaint. At this point, the
investigator may have sufficient information to
formulate a hypothesis, test the hypothesis, and see if
the problem is solved. If it is, steps should be taken
to ensure that it does not recur. However, if
insufficient information is obtained from the walk
through to construct a hypothesis, or if initial tests
fail to reveal the problem, the investigator should move
on to collect additional information to allow
formulation of additional hypotheses. The process of
formulating hypotheses, testing them, and evaluating
them continues until the problem is solved.
Although air sampling for
contaminants might seem to be the logical response
to occupant complaints, it seldom provides information
about possible causes. While certain basic measurements,
e.g., temperature, relative humidity, CO2,
and air movement, can provide a useful "snapshot" of
current building conditions, sampling for specific
pollutant concentrations is often not required to solve
the problem and can even be misleading. Contaminant
concentration levels rarely exceed existing standards
and guidelines even when occupants continue to report
health complaints. Air sampling should not be undertaken
until considerable information on the factors listed
above has been collected, and any sampling strategy
should be based on a comprehensive understanding of how
the building operates and the nature of the complaints.
Solutions to sick building syndrome
usually include combinations of the following:
Pollutant source removal or modification
is an effective approach to resolving an IAQ problem
when sources are known and control is feasible. Examples
include routine maintenance of HVAC systems, e.g.,
periodic cleaning or replacement of filters; replacement
of water-stained ceiling tile and carpeting; institution
of smoking restrictions; venting contaminant source
emissions to the outdoors; storage and use of paints,
adhesives, solvents, and pesticides in well ventilated
areas, and use of these pollutant sources during periods
of non-occupancy; and allowing time for building
materials in new or remodeled areas to off-gas
pollutants before occupancy. Several of these options
may be exercised at one time.
Increasing ventilation rates
and air distribution often can be a cost effective means
of reducing indoor pollutant levels. HVAC systems should
be designed, at a minimum, to meet ventilation standards
in local building codes; however, many systems are not
operated or maintained to ensure that these design
ventilation rates are provided. In many buildings, IAQ
can be improved by operating the HVAC system to at least
its design standard, and to ASHRAE Standard 62-1989 if
possible. When there are strong pollutant sources, local
exhaust ventilation may be appropriate to exhaust
contaminated air directly from the building. Local
exhaust ventilation is particularly recommended to
remove pollutants that accumulate in specific areas such
as rest rooms, copy rooms, and printing facilities. (For
a more detailed discussion of ventilation, read
Indoor Air Facts No. 3R, Ventilation and Air Quality in
Office Buildings.)
Air cleaning
can be a useful adjunct to source control and
ventilation but has certain limitations. Particle
control devices such as the typical furnace filter are
inexpensive but do not effectively capture small
particles; high performance air filters capture the
smaller, respirable particles but are relatively
expensive to install and operate. Mechanical filters do
not remove gaseous pollutants. Some specific gaseous
pollutants may be removed by adsorbent beds, but these
devices can be expensive and require frequent
replacement of the adsorbent material. In sum, air
cleaners can be useful, but have limited application.
Education and communication
are important elements in both remedial and preventive
indoor air quality management programs. When building
occupants, management, and maintenance personnel fully
communicate and understand the causes and consequences
of IAQ problems, they can work more effectively together
to prevent problems from occurring, or to solve them if
they do.
Contents
For more information on topics discussed
in this Fact Sheet, contact your state or local health
department, a non-profit agency such as your local American
Lung Association, or the following:
National Institute for Occupational
Safety and Health
www.cdc.gov/niosh/homepage.html
US Department of Health and Human Services
4676 Columbia Parkway (Mail Drop R2)
Cincinnati, Ohio 45226
Public Relations Office
American Society of Heating, Refrigerating and
Air-Conditioning Engineers (ASHRAE)
www.ashrae.org/
1791 Tullie Circle, NE,
Atlanta, Georgia 30329
Building Owners and Managers
Association International
www.boma.org/
1250 Eye Street, NW,
Washington, DC 20005
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