SALT LAKE CITY — Summer brings more than just baseball and barbecues — it also comes with ozone alerts.

The Utah Division of Air Quality has expanded its pollution forecasts to include Tooele and Box Elder counties, just in time to alert people about summer smog.

"With the growing population of Box Elder and Tooele counties, it's important to include them in our three-day forecasts," said Cheryl Heying, the division's director.

Ozone is formed when vehicle emissions and industrial sources mix with sunlight and heat. Ozone pollution becomes more troublesome on hot summer days and can make it difficult for people to breathe. Prolonged exposure also can lead to lung damage.

The U.S. Environmental Protection Agency's 24-hour standard for ozone is 75 parts per billion.

"It's important for people to check the pollution levels on our website before they drive to work each morning, because certain weather conditions, mixed with vehicle exhaust, can cause ozone to rise. When that happens, we ask people to limit their driving," said Bo Call, manager of the state's Air Monitoring Center.

Click on to find a color-coded, three-day forecast.

— Amy Joi O'Donoghue