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 ndoor air quality is often very poor in school buildings
as a result of deferred maintenance and poor design of the buildings
and heating, cooling and ventilating systems. It is increasingly
recognized as a serious health risk, and "sick building
syndrome" is particularly dangerous for children.
 Sick
building syndrome was once attributed to outgassing of formaldehyde,
organic compounds, and plastics in buildings; but more detailed
studies are showing the fundamental problem is commonly elevated
levels of microorganisms in the inside air. The growth and sporulation
of fungi are also increased by crowding - which increases moisture
levels and carbon dioxide.
We breath
these organisms all the time, whether we are inside or out. But
when the levels rise above threshold levels, these fungi, bacteria,
and viruses can make us very sick. The well known Legionnaire's
disease, for example, is caused by the bacterium Legionella
pneumophila, and aspergillosis is caused by the Aspergillis
fungi. Fortunately, these are fairly rare, but the very common
Cladosporium and Penicillium fungi are linked to
asthma, and Penicillium is probably the most common cause
of allergic responses, such as scratchy throat, itchy, runny
eyes and nose. They also appear to be implicated in increased
airway and sinus infections.
The greatest
health risk is probably posed by the dangerous black fungus Stachyobotris
chartarum, which produces tricothecene toxin. This black
fungus is sometimes found in or under carpets that have been
flooded, but it may also appear in heating and cooling ducts,
or in attics and walls wetted by leaking roofs and walls.
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Visual
inspection will often show the presence of fungi as a black or
greenish smudge or smear, or in severe cases a visible colony
or mat and a cloud of black dust that rises when carpets are
removed. A greenish dust on the air duct in my office was a colony
of Cladosporium with 400,000 spores per square centimeter
when collected and evaluated at a lab (this only costs about
$30-50 dollars). These surface samples are fairly inexpensive
but very crude.
The best sampling
method is repeated air monitoring with a measured volume of air
drawn across a media plate. This should be done three times starting
on Monday, when contamination is often highest as the heating
or cooling systems starts up after a weekend of fungal growth
and sporulation. This is one reason Mondays often seem so hard
to take! This intensive monitoring can cost up to a thousand
dollars per office or room.
A survey of
school employees and students can often help pinpoint problem
areas. For years people who have reported that work made them
sick, allergic (itchy eyes and throat), exhausted, irritable,
dizzy and caused headaches have been ridiculed or considered
hypochondriacs. But new studies of indoor air quality are showing
these symptoms are all consistent with exposure to fungi and
other contaminants in indoor air. There is a very wide range
of tolerance to these contaminants and one worker in an office
may be unaffected while the others are severely affected.
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These
various air contaminants are living organisms or their reproductive
parts and they can only be stopped by eliminating the conditions
that enable them to grow. Cleaning previously contaminated areas
can also help. This is difficult in many cases, particularly
with older air ducts and heating and cooling systems. In many
cases the ducts are fiberglass insulated without lining - effectively
making them a large growth media for microorganisms. Chemical
controls are generally ineffective and may cause problems of
their own, although there is some new hope for new control agents.
For the equally
common problem of carpets that are contaminated, the only solution
is removal. Carpets that are wetted for more than 24 hours may
have to be removed and replaced. Linoleum, tile or chemically
stained and polished concrete would be preferable to carpet in
many locations. Waxing or cleaning these floors may increase
maintenance costs, but these costs would be outweighed by current
costs that individuals and the institution are paying for lost
productivity and health care.
Dust on filter
coils and heat exchangers can provide nutrients for fungi and
other organisms to grow, these should also be cleaned regularly.
Ducts can also be cleaned, but this is difficult and results
are mixed. All new schools and school retrofits should be designed
to minimize mold problems. New European and Canadian designs
provide operable windows, which can help reduce risk.
Because correction
of existing problems is costly and difficult, the immediate response
may be to simple improve air filters on heating and cooling systems,
to add new filters on air outlets to rooms, to provide room air
cleaners for affected individuals (about $400 each), and to plan
for upgrades to the heating and cooling systems and floor coverings
as time allows.
Future planning
for school campuses should stress clean indoor air and should
restrict the outdoor landscape to plants that are less likely
to cause allergic response. The City of Tucson and other communities
have taken the lead in restricting use of very common allergen-producing
plants, such as olive trees. Any future buildings should also
include clean rooms for the 10 - 20 percent of the population
affected with asthma or severe allergies.
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Cooley, J.D., W.C. Wong, C.A. Jumper, and
D.C. Straus. 1998. "Correlation between the prevalence of
certain fungi and sick building syndrome." Occupational
and Environmental Medicine 55:579-584.
Dosman, J.A. and D.W. Cockcoft. 1989. Principles
of Health and Safety in Agriculture. CRC Press, Boca Raton,
Fl421 p.
McGrath, J.J., W.C. Wong, J.D. Cooley, and
D.C. Straus. 1999. "Continually measured fungal profiles
in sick building syndrome." Current Microbiology 38:33-36.
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usiu.edu.