California towns top the list.

By Time.com and Victor Luckerson / Time.com
April 22, 2016
Getty Images/Corbis Documentary

This story originally appeared on Time.com.

The land of miles-long traffic jams is officially one of the most polluted city in the country, according to a new report by the American Lung Association. Los Angeles topped the list for most days with a high level of ozone, the scientific name for smog. Another California city, Bakersfield, led in particle pollution.

These issues can exacerbate lung disease and asthma, as well as stunt lung growth in children, a scientific adviser for the ALA told ABC news.

Overall more than half of the U.S. populace live in places with dangerous levels of smog or particle pollution, according to the report. Several other California cities, including Fresno, Sacramento and San Jose, landed on the pollution lists. On the other end of the spectrum, Bellingham, Wash. was the cleanest city in terms of smog pollution, while Farmington, N.M. was the cleanest in terms of year-round particle pollution.

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