The American Lung Association said today that New London County earned a grade of “F” for smog in its 2014 State of the Air report, and an “A” for 24-hour particle pollution.

The county had 12 “orange” days in 2013, when air was unhealthy for sensitive groups, and 2 “red” days, when air was unhealthy for all groups. There were no “purple” or “maroon” days, the worst in the six-level air-quality ranking system.

Overall, six of the eight counties in the state earned failing grades for high levels of smog, with Fairfield County having the worst overall air quality. The Bridgeport coal plant in Fairfield County contributes to the smog problem there. Litchfield County had the best grade, earning a “C,” and there was insufficient data from Windham County to receive a grade.

Smog pollution makes it difficult to breathe and can trigger asthma attacks, heart attacks, lung damage and even premature death, the association said in a news release.

“This report should be a wake-up call to Connecticut leaders that we need to get serious about cleaning up our air,” said Onté Johnson, Connecticut Organizing Representative for the Sierra Club. “Gov. Malloy can start by working with our community on developing a plan to responsibly move Bridgeport beyond coal.”

Smog pollution is especially dangerous to children, seniors, and people who work, play or exercise outdoors. According to the latest report, more than 350,000 people in Connecticut counties with poor air quality suffer from asthma, including more than 90,000 children.