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Larimer County officials address high ozone levels

By: Amber McIver-Traywick | The Surveyor | June 16, 2022 | Local News

Representatives from the Larimer County Department of Health and Environment discussed the increased level of ground-level ozone and poor air quality in Larimer County and what residents can do to help mitigate the issue during a virtual meeting last Thursday.

Public Health Director Tom Gonzales, Larimer County Environmental Health Director Chris Manley, and Larimer County Medical Director Dr. Paul Mayer presented information about the air quality situation including the most recent data which shows Larimer County along with eight other counties including Adams, Arapahoe, Boulder, Broomfield, Denver, Douglas, Jefferson and Weld are all out of compliance with federal air quality standards. The greatest concern in Larimer County according to Gonzales is ground-level ozone.

According to the Environmental Protection Agency Tropospheric, or ground-level ozone, is not emitted directly into the air but is created by chemical reactions between oxides of nitrogen (NOx) and volatile organic compounds (VOC). This happens when pollutants emitted by cars, power plants, agricultural sources, industrial boilers, refineries, chemical plants, and other sources chemically react in the presence of sunlight. Natural sources like wildfires and dust can also contribute.

The atmosphere and weather contribute to the phenomenon in the region. Gonzales said, “When you have really hot days, lots of sunlight, we don’t have the afternoon clouds and showers, we get this mixture in the afternoon…in some years we see continuous back-to-back hot, dry days with lots of sunlight that just keeps compounding that ground-level ozone.”

“We are most likely being downgraded from the EPA’s “serious” level to “severe,’” Gonzales said, “Shortly or soon probably within late 2023, or 2024, gas stations on the Northern Front Range will be required to sell cleaner-burning gasoline. Again, this change will hit the pocketbook, but it is gasoline that is proven to reduce the precursors that contribute to ground-level ozone.”

Around 500 Larimer County businesses that previously did not have to be permitted but produce ozone precursors will have to obtain permits to remain compliant.

Denver-Aurora as well as Fort Collins rank 7 and 18 respectively on the list of the top 25 most ozone polluted cities in the U.S. according to the American Lung Associations State of the Air 2022 research.

The county currently performs ambient air monitoring for carbon monoxide, ozone and other pollutants and is working to expand its testing capacity. The county also performs CFC compliance inspections, issues open burn permits and investigates air quality complaints. Larimer County is currently within federal compliance for both carbon monoxide and particulate matter.


Manley explained the main contributing factor to ground-level ozone in our area comes from transportation. Refuel your car in the evening when it’s cooler. Finally saying, “The less we can do during the heat of the day the better”

During the discussion, Manley gave several examples of ways residents could help reduce the pollution which included carpooling, using electric vehicles, avoiding idling in your car,  or choosing to bike, walk or telecommute whenever possible. It was also suggested to delay lawn and gardening work that uses gasoline-powered equipment until after 7 at night. Other suggestions included refueling your vehicle in the evening when it’s cooler, “The less we can do during the heat of the day the better,” he said.

Dr. Mayer touched on the health impacts of poor air quality stating there is a measurable decrease in lung function for some people exposed to these pollutants. He commented that the effect of ozone on people is highly variable but that children and the elderly are the most vulnerable to health effects including eyes, nose and throat irritation, and shortness of breath. It can also make asthma and other respiratory symptoms worse.

Dr. Mayer said that to limit exposure to ozone “The single most important thing people can do is avoid exercise during the hottest part of the day” as the creation of ozone is a combination of sunlight and heat. Exercising earlier in the day can limit this exposure. This is particularly important for children and older adults and those with lung disease.

Residents were encouraged by the panel members to be aware of current air quality conditions by visiting sites like to be aware of when you should avoid spending time outdoors.


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