Denver, Colorado – Air quality across Colorado’s Front Range will deteriorate Thursday as hot, stagnant conditions push ozone levels into the “Unhealthy for Sensitive Groups” category, triggering a state-wide Ozone Action Day Alert through 4 p.m.
According to the Colorado Department of Public Health and Environment, the alert covers Denver, Douglas, Jefferson, Boulder, Larimer, Weld, Broomfield, and parts of Arapahoe and Adams counties. While unsettled weather limited ozone development on Wednesday, the buildup of pollution under Thursday’s heat dome poses respiratory risks for children, older adults, and those with asthma or other lung conditions.
The state urges residents to limit use of gas-powered vehicles and lawn equipment until Thursday evening. “Reducing vehicle emissions, even for a day, helps ease the strain on our air,” health officials said. Commuters are encouraged to carpool, use public transit, or delay trips when possible.
In Denver and Boulder, midday highs near 90°F combined with low wind speeds will trap pollutants close to the surface. Weld and Larimer counties could see similar air stagnation by late morning.
Those at higher risk should avoid prolonged outdoor activity, especially during peak afternoon hours.
Another update will be issued if conditions worsen or extend into Friday.
