The Colorado Department of Public Health and Environment issued an action alert warning that smoke from fires in the northwestern U.S. and western Canada will keep air quality in the moderate to unhealthy range for the elderly, children and those with heart or lung disease until at least 4 p.m. Wednesday. “The heaviest smoke impacts on Tuesday and Wednesday are expected to be in the Front Range region, including Fort Collins, Greeley and the Denver metro area, and will lead to particulate levels in the ‘Moderate to Unhealthy for Sensitive Groups’ range,” a CDPHE release said.