Clean Air Colorado

Ozone pollution threatens the health of many Coloradans. We have the solutions to clean up our air — we just need to use them.

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Smoggy skies over Denver

Colorado enjoys a reputation for clear blue skies over “purple mountains majesty” and a healthy, outdoor lifestyle to go along with it. 

But our state has more than its fair share of air quality problems. One of the biggest: ozone pollution.

What is ozone pollution and where does it come from?

The nitrogen oxides (NOx) and volatile organic compounds (VOCs) that form ozone come from a variety of sources such as the oil & gas sector, the cars and trucks we drive, industrial sources and gas-powered lawn and garden equipment.

The worst ozone typically happens between June and August – our “ozone season.” This is the time of year when you may get an ozone alert on your phone or see one on your weather app, warning you to reduce exercise or outdoor activity. 

This is because ground-level ozone can cause harmful health effects including lung damage, worsening of existing respiratory conditions such as asthma, and even cardiovascular disease. For a deeper dive on how ozone is formed and the health impacts it causes, check out our blog and interview with Dr. James Crooks, a researcher at National Jewish Health.

In recent years, the Denver Metro/North Front Range region – roughly from Castle Rock up to Fort Collins and Greeley – has suffered from some of the highest ozone pollution in the country. These high ozone levels mean the region is failing to meet the national health-based air quality standards for ozone, and in 2022, the EPA reclassified the region from “serious” to “severe” nonattainment of these standards.

How can we cut harmful ozone pollution in Colorado?

One thing is clear: to protect our health, we need to get ozone levels down from these unsafe levels as quickly as possible. 

Our best chance for doing this is to reduce the amount of NOx and VOCs entering our air. Because so many sources contribute to the problem, we have lots of solutions at hand for addressing it.

Legislative solutions

In 2023, we called on our legislators to build off previous legislative and regulatory successes and pass a package of policies that address ozone pollution across the board. 

Specifically, we asked state leaders to take concrete action in nine areas outlined in our Ozone Agenda.

In the end, the legislature passed bills expected to make significant progress on five out of the nine action areas highlighted: shifting away from gas-powered lawn and garden equipment; accelerating the adoption of electric vehicles (EVs) and electric bikes (e-bikes); taking steps to increase transit ridership and reduce the need to drive and cutting ozone pollution from buildings.

Administrative action: Gov. Polis calls for 30% NOx cuts by 2025

In March 2023, Colorado Gov. Jared Polis made an announcement directing state agencies to cut ozone-forming NOx from the oil and gas sector by 30% by 2025 and 50% by 2030. 

Oil and gas accounts for about 45% of NOx in the Denver Metro/North Front Range, so a 30% reduction in just this sector would mean a significant reduction of ozone-forming NOx in the region in a short period of time. 

This is a bold goal at a time when we need to act quickly. CoPIRG and allies will watchdog the proposal as it makes its way through the rulemaking process.

Expanding travel options so we don’t have to drive to complete every trip

State and transit agencies should continue to expand travel options including building on the success of Bustang, the state’s intercity bus system, and the Zero Fare for Better Air program (which in 2023, meant free bus and train rides in both July AND August in the RTD region).

We also need to ensure the Colorado Department of Transportation stops wasting hundreds of millions of dollars on highway widening projects that fail to expand options for people getting from point A to point B. 

Local governments should also expand travel choices including incentivizing e-bikes and building out safe and pleasant sidewalks and bike lanes. 

Accelerating transportation electrification

In order for more Coloradans to take advantage of incentives to purchase electric vehicles, we need to continue to expand charging infrastructure across our state so people have confidence they’ll be able to charge where they live, work and play. 

We should also pass the Colorado Clean Cars rule to continue the requirements on dealerships and manufacturers to increase the number of electric vehicles in years 2027 and beyond. Passing the strongest rule possible, through 2035, will maximize benefits for air quality improvement as well as choice for consumers.  

Targeted financial incentives could help Coloradans exchange especially high emitting gas or diesel vehicles for cleaner electric ones. 

We can expand funding for the electric school bus grant program and increase technical assistance to make it easier for smaller school districts to apply for grants. More electric school buses means less exposure to diesel pollution that puts our health and communities at risk.

Working with state agencies for better outcomes

Regional and state air quality agencies such as the Regional Air Quality Council (RAQC) and Air Quality Control Commission (AQCC) hold public processes and rulemakings throughout the year to establish policies to clean up our air. 

CoPIRG and fellow clean air advocates engage in these processes year in and year out to push for the strongest possible outcomes for our health and quality of life.

What can you do to help clean up our air?

  • Whenever possible, bike or walk or ride transit instead of driving. Check to see if your city offers rebates or tax credits for purchasing an electric bicycle/e-bike that can help you replace car trips. If you must drive, look into switching to an electric vehicle (EV) in order to eliminate tailpipe emissions. 
  • Recycle your old gas-powered lawn mower, leaf blower or trimmer. If you need to replace it, use the Regional Air Quality Council’s discounts to purchase an electric or battery-powered model instead. If you hire someone to maintain your property, hire a company that uses only electric equipment. Pound for pound, gas-powered lawn and garden equipment is even more polluting than the cars and trucks we drive, so this can have a big impact on air quality.
  • As you need to replace appliances in your home, consider switching from gas appliances, which release ozone-forming emissions, to electric appliances. You can even get discounts, rebates and/or tax credits for much of this electric equipment. 
  • Follow these tips to weatherize your home to reduce the need to use so much energy for heating and cooling in the first place.
  • Call or write your state and local leaders encouraging them to take action to address each of the nine areas in CoPIRG’s Ozone Agenda.
  • Donate to support the Clean Air Colorado campaign.

By taking action now to cut harmful ozone pollution in our state, we can protect our health and quality of life. We can once again have clean air, Colorado!


Kirsten Schatz

Clean Air Advocate, CoPIRG

Kirsten joined CoPIRG's staff in 2022 and is focused on fighting for clean air for Coloradans and transforming transportation systems. Previously, she oversaw The Public Interest Network's efforts to engage alumni/former employees and volunteers in the network's work, specializing in communications and organizing events in dozens of cities. Kirsten lives in the Denver area with her husband and two children, where she is an avid hiker, biker, church choir member and gardener.

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