DENVER (KDVR) — After a fairly blue-sky Sunday, the ozone concentration level has increased to moderate, prompting the Colorado Department of Public Health and Environment and Air Quality Control to issue an Ozone Action Alert Day until 4 p.m. Tuesday.

As moderate to heavy wildfire smoke from the West is moving into the state, the air quality has decreased. The ozone concentration registered at 71 on the Air Quality Index which is in the moderate category, meaning unusually sensitive people should keep outside activity to a minimum.

The particulate matter level is at moderate which means respiratory symptoms are possible in unusually sensitive individuals, and aggravation is possible for people with cardiopulmonary disease and older adults. Unusually sensitive people should refrain from extended exercise or heavy exertion.