Air Quality Forecast For Metro Denver, Boulder: Aug. 5

Another action day alert for pollution was issued Thursday for parts of the Front Range and Eastern Plains.

Ozone concentrations are expected to be in the 'unhealthy for sensitive groups' to 'unhealthy' categories in metro Denver, Boulder, Greeley and Fort Collins, the Colorado Department of Public Health and Environment said.

Fine particulate matter concentrations from wildfire smoke along the Front Range and Eastern Plains are expected to be in the 'moderate' to 'unhealthy for sensitive groups' categories Thursday, and visibility will be in the 'poor' to 'extremely poor' categories in Denver.

"People with heart or lung disease, older adults, active adults, and children should reduce prolonged or heavy exertion on Thursday," the agency said in its alert.

Carbon monoxide and nitrogen dioxide levels are expected to be in the 'good' category Thursday, health officials said.

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Dozens of action day alerts for ozone have been issued for metro Denver and Boulder so far this summer. Metro Denver is the 8th worst metro area in the nation for high ozone days, according to the American Lung Association's 2021 "State of the Air" report.

Ozone pollution, often called smog, forms when gases that come out of tailpipes and smokestacks, among other sources, come into contact with sunlight. Ozone is "one of the most dangerous and widespread pollutants in the U.S.," the lung association said.

Ozone can damage people's airways, make their lungs more susceptible to infection and aggravate lung diseases, according to the U.S. Environmental Protection Agency.

>> Read the full air quality advisory here.