DENVER (KDVR) — The hazy skies in Colorado on Tuesday are a result of wildfire smoke from the Northwest U.S. and increased levels of ozone.

The photo below is from Tuesday afternoon showing a lot of smoke over Denver.

The smoke is being transported to Colorado in upper-level winds from wildfires in Idaho and Oregon. The worst of the smoke has been in western Colorado on Tuesday but will shift east by Wednesday.

The smoke forecast below shows the thickest smoke across the Eastern Plains Wednesday afternoon.

An air quality alert has been issued for metro Denver and the Front Range until 4 p.m. Wednesday. If you are sensitive to poor air quality, it will be best to workout inside.

The smoke is forecast to stick around on Thursday before a cold front will clear out the haze on Friday.