American Lung Association’s ‘state of the air’ report finds 166 million Americans are living in unhealthy ozone or particle pollution with serious health risks. More than half of the US population lives amid potentially dangerous air pollution, with national efforts to improve air quality at risk of being reversed, a new report has warned. A total of 166 million Americans live in areas that have unhealthy levels of either ozone or particle pollution, according to the American Lung Association, raising their risk of lung cancer, asthma attacks, heart disease, reproductive problems and other ailments. The association’s 17th annual “state of the air” report found that there has been a gradual improvement in air quality in recent years but warned progress has been too slow and could even be reversed by efforts in Congress to water down the Clean Air Act.