A ground-level ozone pollution alert for the Front Range, including the Denver area, has been issued by the state health department.

The alert is in affect until 4 p.m. Wednesday, according to the Colorado Department of Public Health and Environment and the Regional Air Quality Council.

Emissions from everyday materials and items — including gas-powered vehicles and lawn equipment, household paints, stains and solvents — combine with other pollutants on hot summer days, leading to higher levels of ground-level ozone pollutants.

Ground-level ozone can be harmful to everyone, but the young and elderly are at a heightened threat. People with pre-existing health conditions, including asthma and other respiratory infections, are most susceptible.

Symptoms include breathing difficulties and eye irritation, as well as lower resistance to colds and lung infections.

The Front Range corridor from El Paso County north to Larimer and Weld counties, including the Denver-Boulder area, Colorado Springs, Fort Collins and Greeley, is under the alert.

Ozone concentrations are expected occasionally to reach unhealthy levels for sensitive groups Tuesday and Wednesday.

People exercising outdoors and those doing physical jobs or tasks outdoors should be aware of the conditions and react accordingly, the health department advises. Unusually sensitive people should consider reducing prolonged or heavy exertion.