The Initiative will not look at health records or collect human health information. A study of that type would require a much longer period of time, would be costly, and would need to include a health assessment of other factors such as tobacco use, diet, and the socioeconomic background of people of the region. Studies of this type in other places show that these factors contribute much more to the health effects people experience than do environmental causes such as toxic air pollutants. The toxic air pollutants of greatest concern are those that cause serious health problems or affect many people. Health problems can include cancer, respiratory irritation, nervous system problems, and birth defects.
Some health problems occur very soon after a person inhales a toxic air pollutant.
These immediate effects may be minor, such as watery eyes. Or they may be serious, such as life-threatening lung damage. Other health problems may not appear until many months or years after a person's first exposure to the toxic air pollutant. Cancer is one example of a delayed health problem. In hazard identification, scientists evaluate all available information about the effects of a toxic air pollutant to estimate the likelihood that a chemical will cause a certain effect in humans.