The majority of the work environment is served by mechanical HVAC systems. These systems are designed to provide a comfortable temperature and humidity range throughout the year. They are also designed to bring in fresh outside air. Fresh air is drawn in and mixed with return air. An equal amount of air is exhausted to the outside. If the fresh outside air is not sufficient, carbon dioxide will accumulate in the building. Carbon dioxide is an indicator for indoor pollutants since it is directly related to the number of people in the building. If carbon dioxide levels are too high there is not enough ventilation air. Sources of indoor air pollution include biological organisms, outgasing from building materials and furnishings, outgasing from cleaning materials, ozone from copy machines, and pesticides. Control of indoor pollutants is two pronged. First, it is important to control and or eliminate the pollutants. Second, it is important to have enough fresh outside air to dilute the remaining pollutants. It is also important to have local exhaust from problem areas like copy machine rooms, areas where solvents are used, and bathrooms (EPA 1990, 1–2).
In 1984, the World Health Organization reported that up to 30 percent of buildings were the subject of complaints about indoor air quality. The problem was most often the result of poor maintenance and operation of the buildings. Sick building syndrome (SBS) is the situation where occupants experience discomfort and health issues related to time spent in a building. People report headaches, fatigue, dizziness, nausea, and eye, nose, or throat irritation. The symptoms are relieved when not in the building, but the cause of the symptoms is not known and usually very hard to pin down. The solution is usually to take a careful look at indoor air pollutants and to increase outside air ventilation rates. Indoor pollutant sources can be chemical, volatile organic compounds (VOCs) that come from almost everything inside a building. Indoor pollutants can also come from biological sources like mold, pollen, and bacteria. Another source of indoor air contamination is chemical or biological contaminants coming in with the fresh air being drawn into the building. This includes vehicle exhaust, and building exhausts as a result of badly located fresh air intakes. Building related illness (BRI) is where there is a specific cause for cough, fever, chills, and muscle aches. An example of BRI is Legionnaires’ Disease, which is caused by a bacterium that grows in poorly treated cooling tower water. The aspirated water from the cooling tower then finds its way into the building through poorly located outside air intakes (EPA 1991, 1–2).