Background EPA studies of human exposure to air pollutants indicate that indoor levels of many pollutants often are significantly higher than outdoor levels. These levels of indoor air pollutants are of particular concern because it is estimated that most people spend approximately 90 percent of their time indoors. In recent years, comparative risk studies performed by EPA and its Science Advisory Board have consistently ranked indoor air pollution among the top five environmental risks to public health. EPA, in close cooperation with other federal agencies and the private sector, has begun a concerted effort to better understand indoor air pollution and to reduce peoples' exposure to air pollutants in offices, homes, schools and other indoor environments where people live, work and play. Tobacco smoking has long been recognized as a major cause of death and disease, responsible for an estimated 434,000 deaths per year in the United States.
Tobacco use is known to cause lung cancer in humans, and is a major risk factor for heart disease.
The report was prepared by ORD's Office of Health and Environmental Assessment. Public and Scientific Reviews A draft of this assessment was released for public review in June 1990. Incorporating these recommendations, the Agency again transmitted a new draft to the SAB in May of 1992 for a second review. EPA also received and reviewed more than 100 comments from the public, and integrated appropriate revisions into the final risk assessment. ETS has been classified as a Group A carcinogen under EPA's carcinogen assessment guidelines.