By Seth Klamann, Denver Gazette Aug 26 2021

Residents in North Denver and Commerce City had the highest levels of fine particle pollution of anywhere in Denver or any city in Colorado during the past three months, data collected by the state shows. The exposure risked the health of some residents.
The state Department of Public Health and Environment dispatched its mobile lab to the area in May, it said in a press release, “because of department and community concerns regarding air quality in the area.” Between May 14 and July 17, the lab collected pollution data and found that fine particulate matter – emitted by vehicles, coal-fired power plants and wildfires – were high enough to pose health risks to some at-risk people, like children or people with respiratory or cardiac issues.
The pollution “comes from local sources,” the health department said, like vehicles and the Suncor refinery located in Commerce City. In a settlement with the state, Suncor agreed to spend $12 million on improving its refinery technology and operations. Wildfire smoke, another contributor, contains this type of particulate matter and comes from outside of the state from fires elsewhere. For reasons experts don’t entirely understand, local fires typically do not carry that type of pollutant when they’re fresh, researchers previously told the Gazette.