Suffolk County continues to have the worst measured smog problem in the state, and pollution from soot, diesel exhaust and other sources rose last year, the American Lung Association [1] of the Northeast reported.

Auto emissions are a major contributor to smog.In its annual State of the Air report card released Wednesday, the Lung Association gave Suffolk an "F" for the 13th year in a row for ozone. The primary ingredient in smog, ozone [2] is  a gas that forms when emissions from factory and power-plant smokestacks and car and truck tailpipes react with sunlight.

Joining Suffolk in failing grades for ozone pollution were  Chautauqua, Jefferson, Putnam and Westchester counties, along with Staten Island in New York City. However, this represents an improvement over 2011 [2], when 16 of the 34 New York counties that test for ozone pollution got an "F."

Suffolk County dropped from an A to a B for particle pollution, making it the only county in New York State to drop a grade for either pollutant.  A "B" grade still is considered "acceptable" by the Lung Association.

Nationally, 127 million Americans live in counties with poor air quality, air quality expert Janice E. Nolen, who authored the report, told Newsday [3]. Of those, 3.2 million live in New York State.

The New York City metro area ranked 15th on the list of 25 cities most polluted by ozone but dropped off the list of 25 most polluted cities for particle pollution.

Areas with heavy traffic tend to have high levels of pollution, although faraway places with coal-fired power plants export their pollutants eastward. Advocates say another threat to air quality improvement is the proposed Gasoline Regulation Act of 2012 [4], which would delay tougher tailpipe emission standards.