Sick buildings - sick people

Why your children may be having trouble breathing.

by David Bainbridge


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.


How can these be detected?


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.


What can be done about poor indoor air quality?


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.


Further reading

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.

David Bainbridge Environmental Studies Coordinator United States International University 10455 Pomerado Road San Diego, CA 92131, 858-635-4616;