With temperatures heating up, the Utah Division of Air Quality's "Choose Clean Air Red Light Green Light" program is now focusing on alerting people about summer smog.

The division is tracking levels of ozone pollution, caused mainly by vehicle emissions and industrial sources. Ozone pollution becomes more troublesome on hot summer days and can make it difficult for people to breathe.

"Summer is a great time to be outdoors," said division director Cheryl Heying. "Smoggy conditions, however, can make it unpleasant and even unhealthy at times. That's why the Choose Clean Air program is crucial to inform residents when the air is unhealthy and help them make choices to prevent the pollution from getting worse."

Last year, the federal Environmental Protection Agency tightened the ozone standard, reducing the allowable amount of ozone from 80 parts per billion to 75.

"This makes it even more crucial for people to check conditions, because we may be asking people to limit their vehicle use even more this summer, depending on weather conditions," said Bo Call, manager of the Air Monitoring Center. Call replaced longtime manager Bob Dalley, who retired early this year.

Click on airquality.utah.gov to find a color-coded three-day forecast for Salt Lake, Davis, Cache, Weber and Utah counties.

"Green" means air quality is good and people are encouraged to make clean air choices to help keep air-pollution levels low. "Yellow" means the pollution is building and people are encouraged to take proactive steps by voluntarily carpooling, consolidating vehicle trips and avoiding idling or mowing the lawn in the middle of the day. "Red" means pollution levels are critically high, and residents should avoid using gasoline and diesel-powered engines.

— Amy Joi O'Donoghue