While the smoke is worst along the Western Slope where the fires are burning, levels are also fluctuating on the Front Range.

Official air-quality results for Kyrene de la Sierra Elementary School show elevated levels of potentially harmful chemicals.

Allegheny County is increasing air quality monitoring after an explosion at a U.S. Steel plant south of Pittsburgh killed two ...

Despite thick smoke in the sky today in southern Colorado, air quality alerts haven't been issued - instead they've been in the western slope. In fact - sometimes invisible compounds pose more risk.

An air quality alert was reported by the National Weather Service on Tuesday at 12:17 p.m. in effect until 8 p.m. for ...