Lake County

has the area’s most unhealthy air when it comes to ozone smog, according to the American Lung Association’s State of the Air report. Lake got a C, Orange a B and Seminole and Osceola each scored an A.

Though dwarfed in population and traffic by its neighbor, Lake County has the Orlando area’s most unhealthy air when it comes to ozone smog, according to the American Lung Association’s State of the Air report.

Lake got a C, Orange a B and Seminole and Osceola each scored an A. In Florida, only Tampa’s county, Hillsborough, was marked with an F.

Janice Nolen, an association assistant vice president, said Lake may be the victim of pollution from Orange and Seminole. Tailpipes, factories, power plants and other sources emit ingredients that are converted by heat and sunlight to ozone smog.

“Ozone often shows up downwind from those sources. It’s a very creative pollutant,” she said. “In many metropolitan areas, it will show up a little bit downwind of where you see the largest urban population.”

Though invisible, ozone smog is linked to worsened asthma and COPD, heart attacks and strokes, and reproductive and nervous-system harm.

Nationally, smog has decreased markedly as cars, fuels and industry have gotten cleaner.

The 2018 State of the Air report is based on data from 2014 through 2016. During that period, Orange County reported an average of less than one unhealthy ozone day per year.

But in 1998 through 2000, Orange had 26 days a year on average of unhealthy ozone smog as measured by current federal standards.

The lung association considers today’s limits to be far too lax. They were imposed by the U.S. Environmental Protection Agency nearly three years ago after contentious debate between health advocates and industry representatives.

Of 227 metro areas, Orlando is tied with several others — including Colorado Springs, Colo.; Rochester, N.Y.; and Columbia, S.C. — as the 112th most polluted by ozone.

Los Angeles is the most polluted and others among the worst 25 are Phoenix, Las Vegas, Denver, Dallas, Chicago, New York and Atlanta.

More than 50 metro areas recorded no unhealthy days for ozone pollution and are ranked as the cleanest. They include Anchorage, Alaska; Bangor, Maine; Rapid City, S.D.; Tallahassee, Melbourne and Sebring.

The Orlando area ranks far better in another category, one that takes into account mixtures of noxious chemicals in the atmosphere.

Called particle pollution, each speck is far too small to see, although high concentrations can make the air hazy.

The Orlando metro area ranks as the nation’s 25th cleanest for “year-round particle pollution.”

Several other Florida cities rank among the cleanest 25 but not larger ones, such as Tampa, St. Petersburg, Jacksonville or those in South Florida.

Particle pollution is a mix of chemicals from tailpipes, chimneys and other sources that react in the atmosphere. The particles are so small they pass through lung tissue into the bloodstream, causing havoc.

“Particle pollution and ozone pollution both can short life — they can literally kill you,” Nolen said. “But particles are much more lethal at that than ozone. We now know that particle pollution causes lung cancer.”