We would like to train our employees about the health effects of indoor air pollution. What are some of the main points that should be covered?

Health effects from indoor air pollutants fall into two categories:

• Those that are experienced immediately after exposure; and
• Those that do not show up until years later.

Immediate effects, which may show up after a single exposure or repeated exposures, include irritation of the eyes, nose, throat, headaches, dizziness, and fatigue; immediate effects are usually short-term and treatable. Sometimes, the prescribed treatment is to simply eliminate the person’s exposure to the source of the pollution, if the source can be identified. Symptoms of some diseases, such as asthma, can show up soon after exposure to some indoor air pollutants.

The likelihood of an individual developing immediate reactions to indoor air pollutants depends on several factors, such as age and pre-existing medical conditions. In other cases, whether a person reacts to a pollutant can be determined by individual sensitivity, which varies from person to person. Some people can become sensitized to biological pollutants (i.e., molds, mildews) after repeated exposures, and it appears that some people can become sensitized to chemical pollutants (i.e., carbon monoxide, nitrogen oxide) as well.

Certain immediate effects are similar to those from colds or other viral diseases, so it is often difficult to determine if the symptoms are a result of exposure to indoor air pollution, or some other factors. For this reason, it is important to pay attention to the time and place the symptoms occur. If the symptoms fade or go away when an employee is away from work, and return when the employee returns to work, an effort should be made to identify indoor air sources at the worksite that may be possible causes.

Some health effects may be made worse by an inadequate supply of outside air or from the heating, cooling, or humidity conditions prevailing at the worksite. Others may show up either years after the exposure has occurred, or only after long or repeated periods of exposure. The consequences of these types of exposures can include respiratory diseases, heart disease, and cancer.

While pollutants commonly found in indoor air can be responsible for many harmful effects, there is considerable uncertainty about what concentrations or periods of exposure are necessary to produce specific adverse health effects. Further research is needed to better understand which health effects can occur after exposure to the low-level pollutant concentrations, as well as higher-level concentrations.