Letter to AQCC calling for a stronger ozone State Implementation Plan (SIP)

18 organizations sign on in support

On Nov. 29, CoPIRG Foundation and 17 coalition partners submitted a letter to the Air Quality Control Commission (AQCC) calling on the agency to make a strong plan that will truly address the harmful levels of ozone pollution on Colorado's Front Range.

Here is the text of the letter: 

November 29, 2022

Martha Rudolph, Chair
Air Quality Control Commission
4300 Cherry Creek Drive South
Denver, CO 80246

Dear Commissioner Rudolph and the rest of the Air Quality Control Commission,

The Denver Metro/North Front Range (DM/NFR) region cannot afford to miss the attainment goals for ozone again. 

It is critical that the AQCC approve an ozone State Implementation Plan (SIP) that is strong and includes control measures that reduce ozone precursor emissions enough to meet EPA air quality standards. 

In recent years, the SIP modeling has missed the mark and resulted in too few meaningful pollution reductions and dozens of dangerous ozone alert days. This SIP must be more proactive and achieve real pollution reductions, which is why we write to you today in support of adding further control measures.

The cost of missing our attainment goals is high.

Because ozone pollution comes from a chemical reaction between sunlight, oxygen, and a mixture of pollutants including NOx (nitrogen oxides) and VOCs (volatile organic compounds), it is critical that we reduce the sources of NOx and VOCs in everything from motor vehicle exhaust to lawn and garden equipment to oil and gas production to industrial processes.

The health and economic impacts of failing to address ozone nonattainment are high. People’s health and quality of life are on the line and ozone fuels the climate crisis, which in turn fuels hotter days that increase the risk of ozone alerts.

According to the American Lung Association’s (ALA) 2022 State of the Air report, the Denver-Aurora metropolitan area’s failing grade for high ozone days means 3.6 million people are at risk of harm to their health, including 1.2 million people of color. Ozone impacts hit especially hard in disproportionately impacted communities (DICs), which suffer from the cumulative impacts of additional air pollution as well as soil and water pollution. High ozone levels on top of high localized pollution can lead to even worse health outcomes in the very communities that often have limited access to health care.

Ground-level ozone can have particularly severe impacts on people with underlying health conditions. According to the ALA, in the Denver-Aurora metropolitan area alone this includes:

  • 59,113 children with pediatric asthma,
  • 274,959 adults with asthma,
  • 125,939 people with Chronic Obstructive Pulmonary Disease (COPD),
  • 162,350 people with cardiovascular disease and
  • 39,619 pregnant people who are exposed to adverse health impacts to themselves and their developing fetuses.

As scientists have studied air pollution over the decades, we have learned that ozone impacts not just our lungs but also cardiovascular disease and other conditions. A 2016 study even showed that ozone pollution is cutting our lives short: “When compared with the counties with the lowest ozone concentrations, the counties with the highest ozone concentrations had 1.7- and 1.4-year lower mean life expectancy in males and females (both P < 0.0001), respectively.”

In 2022, health experts issued 46 ozone action alert days. These public health warnings go against Coloradans’ outdoor lifestyle and quality of life. It also threatens the tourism industry, which in 2019 contributed $24.2 billion to our economy and supported 180,000 jobs.

It is time for our SIP to meet the moment and meaningfully reduce ozone precursor emissions in a way that ensures that the DM/NFR area comes into attainment. No single solution will get us there; we need the AQCC to commit to a combination of strong measures that will significantly reduce pollution, taking into account which controls have the biggest impacts on the sources of ozone that contribute to disparate impacts on communities in the nonattainment area. We urge you to consider adopting the following additional strategies in the ozone SIP before you:

  1. Committing to the adoption of Advanced Clean Cars II (ACC II) in 2023;
  2. Committing to the adoption of Advanced Clean Trucks standards in 2023;
  3. Curtailing high emitting oil and gas activities during ozone season through a pause on oil and gas drilling and/or by minimizing vehicle and engine idling, reducing truck and employee traffic, delaying vehicle refueling, suspending or delaying use of gas-powered ancillary equipment, and postponing construction and maintenance activities; 
  4. Requiring electrification and more stringent pollution limits for small and large gas-fired reciprocating international combustion engines in the oil and gas industry;
  5. Retrofitting all existing pneumatic devices with zero-emitting devices; 
  6. Establishing offsetting requirements and aggregation of minor oil and gas wellhead and production facility sources for permitting;
  7. Adopting indirect source rules (ISR) for at least one sector, such as the warehouse sector;
  8. Phasing out the sale of gasoline-powered lawn and garden equipment, and increasing incentives for individuals and small businesses switching from gas-powered equipment to electric;
  9. Committing to additional/permanent funding for strategies to reduce vehicle miles traveled (VMT) such as zero-fare transit, increased transit services, and bicycle and walking infrastructure;
  10. Establishing low NOx appliance requirements for residential and commercial buildings, e.g. for water heating and cooking appliances;
  11. Strengthening the vehicle inspection and maintenance program;
  12. Requiring flare minimization plans for oil and gas operations;
  13. Establishing flaring controls or a flare minimization plan at the Suncor refinery;
  14. Adopting non-road engine standards for heavy-duty off-road compression-ignition engines and large off-road spark-ignition engines 25 hp or greater; 
  15. Evaluating the introduction of a low carbon fuel standard; and
  16. Removing “startup, shutdown & malfunction” (SSM) affirmative defenses from state regulations and not allowing new exemptions.

Every year we fail to meet ozone health levels is another year millions of people in Colorado are unnecessarily exposed to dangerous levels of ozone pollution. Now is the year we need the AQCC to step up and require a strong SIP with meaningful control measures.  

To that end, our organizations support the control measures listed in this letter. The AQCC should consider the policies put forth to develop and adopt a package of rules based on those recommendations to protect the health and future of Coloradans.

Thank you for your hard work and consideration.


Kirsten Schatz, Clean Air Advocate, CoPIRG (Colorado Public Interest Research Group)

Tracy Coppola , Colorado Senior Program Manager, National Parks Conservation Association

Ramesh Bhatt, Conservation Chair, Colorado Sierra Club

Shaina Oliver, State Coordinator, Moms Clean Air Force Colorado Chapter

Joro Walker,  General Counsel, Western Resource Advocates

Scott Simmons, Leader, Climate Reality Project Northern Colorado

Leslie Glustrom, Senior Advisor, Clean Energy Action

Paul Culnan,  Policy Analyst, Empower Our Future

Katara Burrola , Environmental Justice Organizer, Mi Familia Vota

Jeff Neuman-Lee,  Climate Justice Legislative Team Co-Chair, Together Colorado Climate Justice Committee

Andrew Forkes-Gudmundson , Senior Manager for State Legislative and Regulatory Affairs, Earthworks

Alana Miller, Climate and Clean Energy Program Colorado Policy Director, Natural Resources Defense Council

Kevin Cross, Convener, Colorado Coalition for a Livable Climate

Gordon MacAlpine, Convener, Estes Valley Clean Energy Coalition

Fran Aguirre, President, Unite North Metro Denver

Harmony Cummings, Connector, The Green House Connection Center

Amy Petré Hill, Executive Director, Mental Health & Inclusion Ministries

Moshe Kornfeld, Director, Colorado Jewish Climate Action



Kirsten Schatz

Clean Air Advocate, CoPIRG Foundation

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.