The Colorado Department of Public Health and Environment-issued advisory now includes Larimer, Weld, Boulder, Clear Creek, Jefferson, Denver, Park, Douglas, Park, Teller, El Paso, Fremont, Custer, Pueblo, Crowley, Kiowa, Huerfano, Otero, Bent, Prowers, Las Animas and Baca counties.
Officials advise remaining indoors if smoke becomes thick in your neighborhood:
This is especially true for those with heart disease, respiratory illnesses, the very young, and the elderly. Consider limiting outdoor activity when moderate to heavy smoke is present. Consider relocating temporarily if smoke is present indoors and is making you ill. If visibility is less than 5 miles in smoke in your neighborhood, smoke has reached levels that are unhealthy.
The advisory, which was issued earlier this week, is now set to expire at 9 a.m. Thursday.
"Increasing atmospheric mixing along with some showers and thunderstorms may bring improved conditions," CDPHE says. "However, unhealthy levels of smoke will continue periodically over the advisory area."
Even if things improve, that’s no reason to let your guard down, says Dr. Anthony Gerber, a pulmonologist at National Jewish Health.
“It’s unlikely that the level will drop into the good range immediately," he said. "Certainly caution is warranted for at least the next several days."
That's especially true for people with lung disease, older adults and children. Gerber also says that visitors and newcomers to Colorado’s high altitude should also be cautious.