In the industrialized nations of the world people spend 90 percent of their time indoors and the greatest airborne health risks may be posed by indoor air pollution. Occupational exposures are common. A survey of outpatients seen in the primary care clinic of a Midwest hospital found that three-quarters of the men interviewed had been exposed to at least one potentially toxic agent at work and over 30 percent had been exposed to more than four potential toxins. Chemical fumes, solvents, pesticides and asbestos were the most common exposures.

For many of my patients, the presence of an indoor toxic exposure has gone unnoticed until after illness develops, for example a school undergoes construction while classes continue, causing a high rate of sickness among students and teachers. At another school with a poorly-vented furnace, children come home smelling of soot and their school performance deteriorates. In one concert hall in which the air intake vents leading to the orchestra pit are located above the loading dock where the trucks idle, the musicians become sick. In a bedroom in which the condensation beneath a waterbed is slowly disintegrating the particleboard frame, releasing fumes of formaldehyde, the residents suffer insomnia, profound fatigue and bouts of coughing.

Toxic exposures to specific chemicals encountered at work account for 70,000 deaths a year in the United States, with 350,000 new cases of occupationally-related environmental illness appearing each year. Beyond disease caused by individual toxins lies a broad spectrum of health problems caused by the buildings in which people work.

The World Health Organization has defined the "sick building syndrome" as a group disease, the occurrence of excessive work- or school-related illness among workers or students in buildings of recent construction. The symptoms may include lethargy, dry or sore throat, stuffy nose, headache, irritation of the eyes, chest tightness, impaired memory and concentration, dizziness, nausea, itching, skin rash and shortness of breath.

In about one-quarter of the cases a specific source of indoor air pollution can be found: either an accumulation of motor vehicle exhaust or contamination of a humidification system with mold, producing allergic reactions among the building’s occupants. In most cases, however, no single source of contamination can be identified. Yet a survey of nine thousand office workers in three European countries found that 50 to 80 percent of those working in modern office buildings reported symptoms typical of the sick building syndrome. At any one time, 10 to 25 million workers in a million U.S. office buildings suffer from building-related illness. The personal and economic impact of this modern miasma is considerable, because symptomatic workers feel lousy, have reduced productivity and are absent more.

The original name of sick building syndrome was "tight building syndrome." It was believed that tightly-sealed buildings, which do not allow much outside air to seep in, acted like sumps to concentrate the level of indoor air pollutants. This theory has not been borne out. Increasing the supply of outdoor air does not prevent or relieve the symptoms of people working in sick buildings. It appears that sick building syndrome is caused by the presence of chemical toxins or airborne microbes that cannot merely be diluted away.

Two broad categories of pollutants have been implicated as the culprits. The first category are volatile organic compounds (VOCs), invisible gases emitted from paints, adhesives, carpeting, wall coverings, new furniture, building materials, solvents, cleaning solutions, copy machines and laser printers. Studies using experimental chambers have shown that VOCs can cause irritation of the respiratory system in humans and animals at levels one hundred times weaker than permissible exposure levels of the World Health Organization Indoor Air Guidelines. Controlled experiments with people who describe themselves as sensitive to VOCs confirm that VOC exposure causes headache, fatigue and difficulty concentrating. People who deny such sensitivity also experience symptoms but do not encounter mental impairment when exposed. Air samples of buildings with and without sick-building complaints have established an association between VOC exposure and human sickness.

The second category of sick-building culprits are the bioaerosols, which consist of living bacteria or fungi (molds and yeasts) or their toxic by-products or fragments, circulating in the air supply. If live microbes circulate as aerosols, respiratory infection may occur. Legionnaires’ disease is the best-known example. An epidemic of pneumonia (182 cases with 29 deaths) disrupted an American Legion convention in a Philadelphia hotel during the summer of 1976. The epidemic was traced to a bacterial species, subsequently named Legionella pneumophila, which contaminated the hotel’s air-conditioning system. At least 20, 000 cases of Legionnaires’ disease occur in the United States every year. There are 20 different species of Legionella bacteria. They all thrive in stagnant water and have caused epidemics of flulike illness in resorts and hotels throughout the world.

Some scientists believe that fungal or bacterial toxins may be responsible for the more common symptoms of sick building syndrome. European studies reveal that sick building syndrome is more likely to occur in the air-conditioned buildings than in buildings with natural ventilation ducts supporting the growth of microbes, which disperse fragments of their membranes or toxic secretions into air ducts. A recent study from the Georgia Environmental Technology Consortium found that samples of fungi (molds) growing in sick buildings actually produce their own VOCs identical to the VOCs originating in building materials.

• Don’t allow tobacco smoking inside your home.
• Remove shoes upon entering your home from outside.
• Maintain a relative humidity of 30 to 45 percent in each room of your home.
• Do not carpet areas like kitchens and bath rooms that are prone to dampness.
• Dust frequently and clean all horizontal surfaces with a damp rag or wet mop twice a week.
• Remove moldy foods from the refrigerator promptly.
• Make certain that all stoves, heaters and dryers are properly maintained and vented.
• Do not use gas appliances that run with a continuous pilot light.
• Test home air for carbon monoxide and formaldehyde. Call the Consumer Products Safety Commission at 1-800-638-2772.
• Filter tap water through activated charcoal to remove aluminum, lead and cancer-promoting derivatives of chlorine.
• Use air filters and environmentally safe consumer products.