The BPA environmental impact statement.

The Bonneville Power Administration began to look into indoor air quality in 1981 when it planned an extensive weatherization programme. Alternatives were examined for increasing energy savings without increasing health risks. Itwas found that house tightening could increase existing pollutant concentrations in a home by up to 30%. Scientists estimated that each year,between two and thirty five people in every hundred thousand develop cancer from exposure to indoor air polluted by benzo-(a)-pyrene, radon, and formaldehyde.