United States Environmental Protection Agency

About the author: The Environmental Protection Agency (EPA), created in 1970, is the federal agency in charge of controlling and preventing air and water pollution caused by contaminants and toxins. EPA headquarters are in Washington, D.C.

Secondhand smoke, also known as environmental tobacco smoke or ETS, is harmful to human health. Considerable evidence drawn from scientific investigations and epidemiology studies proves that secondhand smoke can cause respiratory illnesses and lung cancer in nonsmokers. Critics of these findings contend that the Environmental Protection Agency has manipulated data to arrive at a predetermined conclusion, and that no studies have definitively confirmed a causal relationship between secondhand smoke and cancer. However, all of the epidemiology studies reveal that people who have longer-term exposure to secondhand smoke face an increased risk of developing lung cancer.

In early...