EPA ReportINTRODUCTION
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.
Causes of Sick Building Syndrome
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.
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.
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.
Building Investigation Procedures
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
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.
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.
Additional Information
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:
Indoor Air Quality Information Clearinghouse [IAQ INFO]
(sponsored by the U.S. EPA)
PO Box 37133
Washington D.C. 20013-7133
(703) 356-4020 or 800-438-4318
fax: (703) 356-5386 or e-mail: iaqinfo@aol.com
You can order additional copies of this fact sheet and others in the Indoor Air Series
from IAQ INFO.
National Institute for Occupational Safety and Health
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)
1791 Tullie Circle, NE, Atlanta, Georgia 30329
Building Owners and Managers Association International
1250 Eye Street, NW, Washington, DC 20005
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