Regional Air Quality Council
Brown clouds are common along the Front Range on very cold days with little wind to mix the atmosphere.
A new report released from the American Lung Association shows there is still room for improvement of air quality across Colorado.
Smoke from the High Park Fire has prompted the Colorado Department of Public Health and Environment, along with the Regional Air Quality Council, to issue an Ozone Action Day Alert.
With the warmer temperatures come ozone alerts. The Regional Air Quality Council kicked off those alerts on Wednesday.