Cities are home to an increasing majority of the world's people, exposing billions to unsafe air, particularly in developing countries, but in rural areas the risk of indoor air pollution is often caused by burning solid fuels.
While Los Angeles led the nation in ozone pollution, San Diego ranked worse than NY, which came in at 10th.
The good news for the west is that two cities-Bellingham, Washington, and Casper, Wyoming-were among some of the cleanest cities, with zero high ozone or high particle pollution days, according to the report.
However, Fayetteville, Greenville and Wilmington experienced zero unhealthy air days and are among the cleanest cities for ozone pollution.
With an estimated population of 1.49 million people, the report revealed that Suffolk residents include a significant number of high-risk individuals, including an estimated 29,000 children with asthma; more than 112,000 adults with asthma; 63,000 adults with COPD and 875 people with lung cancer. Los Angeles once again ranked as smoggiest, a record it has held for the entire 19 years of the association's reporting.
The cleaner air trend in the United States, however, is threatened by a Congress and presidency that seem intent on rolling back gains made in air pollution over the past 45 years.
According to the report, China and India were found to be jointly responsible for over 50% of global deaths attributable to pollution.
Bakersfield took the top spot in a list of cities with another variety of air pollution - small particulate matter, aka soot.
As for cities, the Grand Rapids metro area tied for 34th most polluted in the nation.
Land use patterns on the Wasatch Front have also contributed to worsening air, Siler said.
"We also call on the USA environmental protection agency to implement and enforce the law instead of trying to roll back major safeguards like the clean power plan and cleaner cars, both steps that help us fight climate change and reduce air pollution", Seilback said.
JoAnna Strother, regional director of public policy of the Lung Association in Utah, said the report found unhealthful levels of ozone put Utahns at risk for premature death, asthma attacks and poor health effects for those already breathing impaired. Environmental Protection Agency Administrator Scott Pruitt said earlier this month that he would revoke Obama-era emission limits and establish national standards, threatening California's waiver that allows for stricter emission rules. "It's important for people to pay attention and to fight for cleaner air". "We saw a lot of evidence in 2016 of the impact that climate change and global warming is going to have on us".