Hot, dry weather and wildfire smoke from out-of-state fires will contribute to lower through Friday afternoon, Colorado public health officials said.
State officials expect a rise in ozone and fine particulate levels that will be unhealthy for older adults, children and people with heart or lung disease, according to the Colorado Department of Public Health and Environment.
The agency issued an action day alert at 4 p.m. Thursday that is set to last until at least 4 p.m. Friday. Communities covered by the alert span urban corridor from Douglas County to the south and Larimer and Weld counties to the north, including Denver, Boulder, Fort Collins, Loveland and Greeley.
People who are sensitive to air pollution should not spend long periods of time outside or participate in heavy exercise outdoors, state officials said.
