Over half in U.S. live with dangerous air pollution

By Deborah Zabarenko, Environment Correspondent

WASHINGTON (Reuters) - Six in 10 U.S. residents -- more than 186 million people -- live in areas with dangerous levels of air pollution, the American Lung Association reported on Wednesday.

The air in many U.S. cities became dirtier last year, the association said in its annual "State of the Air" report.

"Despite almost 40 years since the Clean Air Act passed in 1970, six in 10 Americans still live in dirty air areas, areas where the air is unhealthful to breathe," the group's Paul Billings said in a telephone interview.

Los Angeles was ranked as the U.S. city with the worst ozone pollution, also known as smog, a position it has held for nine of the past 10 years. Bakersfield, California, was worst for year-round particle pollution and Pittsburgh, Pennsylvania, was worst for short-term particle pollution.

Many major cities -- including Los Angeles, New York, Atlanta, Philadelphia, Washington, D.C., and Baltimore -- have improved air quality over the last decade. But even with these improvements, residents of some of these cities are breathing dirtier air than in previous years, the lung association said.

This year's air pollution numbers were far higher than in last year's report, which found 125 million people, or about 42 percent of U.S. residents, living with unhealthy air pollution.

WORSE THAN LAST YEAR

Particle pollution is composed of tiny bits of soot, diesel exhaust, chemicals, metals and aerosols. These pollutants are measured both by the year-round levels in the air and by periodic spikes in their levels that can last for hours or days.