Colorado air is getting dirtier and dirtier

Air quality across the state is plummeting, and the climate crisis could make it worse

July 14, 2021 5:10 am

A view of downtown Denver looking southwest in the late afternoon of July 13, 2021. (Colorado Department of Public Health and Environment)

It’s not the altitude that’s making it hard to breathe — it’s the dirty air.

It’s no secret that Colorado’s air quality has been in decline for years. This week alone saw health alerts for both smoke-filled skies and ozone levels that had already prompted the Environmental Protection Agency in 2019 to label Denver as a “serious” nonattainment zone. Today, several regions of Colorado’s Front Range face similar downgrades, and the cities of Denver and Fort Collins consistently rank among the worst in the nation for clean air.

Lest it seem the foothills are hogging all the attention, similar declines can be seen statewide.


In 2018, Silverton — a small town in the San Juan Mountains region — logged some of the worst air quality in the state due to increased particulate matter from wildfires. In the years since, the grim impact of wildfires on air quality have affected dozens of communities such as Grand Junction, Glenwood Springs, Grand Lake and Estes Park. In fact, degrading air quality across the American West in general has become such a regular experience that Apple’s weather app now features daily Air Quality Index readings.

Looking closer at Colorado’s July AQIs so far reveals a disturbing trend.

According to the Colorado Department of Public Health and Environment, air quality summaries of daily highs from July 1 to July 12 reveal zero days remained in the “good” range of 50 or below for the Denver metro, at times reaching a whopping 192 AQI. Likewise, Fort Collins and Greeley claim only one of the days as “good,” with Colorado Springs at a mere three days and Grand Junction boasting the high with six out of 12 days at safe levels. Ozone levels also remain a concern for a majority of regions.

For many, the subsequent dry eyes and headaches might feel like a nightmare return to the 1980s when a notorious brown cloud draped ominously over Mile High Stadium. But this is not the 1980s — this time it could get far worse before it gets better.

Dry eyes and headaches might feel like a nightmare return to the 1980s when a notorious brown cloud draped ominously over Mile High Stadium.

Unlike before, it’s not only gas-guzzling vehicles and the extraction of fossil fuels that’s driving us to plug our noses. After decades of inaction, there are at least two factors regarding poor air quality that can be linked to climate change.

The first pertains to winter inversions and excessive summer heat, both of which are exacerbated by climate change and lead to the trapping of air at low levels. The general phenomenon was recently likened to “putting a lid” on a pot by meteorologist Chris Tomer, whereby “everything — the pollution, the smoke, the ozone — gets trapped” and keeps recirculating lower to the ground. As the air becomes increasingly dirty, we are increasingly subjected to breathing in the grime.

A second issue is the obvious increase in wildfire activity and heavy particulate matter that follows. This includes fires beyond Colorado borders as the smoke from other states blankets the Rockies. As fire seasons get hotter, drier and last longer, the coming decades are likely to see significant increases of particulate matter. The impacts on air quality could easily persist for up to six months out of each year.

Together, these phenomena are compounding with the already problematic ozone and pollution levels from the very things that caused climate change to begin with. In combination, Colorado’s air quality is likely to drop even further, creating even more consistently unsafe air to breathe.

Eventually, we will hopefully decarbonize our economy, helping to alleviate air quality issues in the process. However, given the related public health issues that are surely already impacting Coloradans, this matter should immediately strengthen all arguments for accelerating decarbonization, and it warrants even more aggressive efforts and funding for wildfire mitigation practices. It also raises the question of requiring air filtration systems for public buildings, homes, rentals and businesses.

As John Muir once remarked, “Another glorious day, the air as delicious to the lungs as nectar to the tongue.” I don’t know about you, but I’m ready for something sweet.


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Trish Zornio
Trish Zornio

Trish Zornio is a scientist, lecturer and writer who has worked at some of the nation's top universities and hospitals. She’s an avid rock climber and was a 2020 candidate for the U.S. Senate in Colorado.