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August 12, 2021

Northern Front Range breaks record for poor air quality

Ozone at unhealthy levels for much of summer

Boulder County, CO - The Denver Metro North Front Range, including Boulder County, has had more than 53 ozone action alerts since May, breaking the record for number of alerts issued in a single season since record keeping began in 2011. Previously, 2018 had the highest number of ozone action alerts. In recent days, due to climate change-fueled wildfires burning across the American West, the Colorado Department of Public Health and Environment has issued action alerts for multiple pollutants that include both ozone and fine particulate pollution from smoke.

“The health hazards associated with smoke are compounded by high ozone," said Bill Hayes, Air Quality Coordinator for Boulder County Public Health (BCPH). "The Denver Metro North Front Range, an area already failing to meet federal health-based ozone standards, has now seen 39 consecutive days of ozone action alerts. With both smoke and ozone at dangerous levels, Colorado’s beloved outdoors can be an unhealthy place to be when it comes to your heart and lungs.”

With more smoke and high temperatures predicted this summer, BCPH urges residents to learn how to protect themselves from heart and lung damage. Individuals can sign up for Colorado’s action alerts and check air quality conditions here.

BCPH recommends taking the following actions when air quality is poor:

  • Remain inside with the windows and vents sealed
  • Avoid exertion outdoors when visibility is less than five miles or on afternoons and evenings when ozone is high
  • If individuals cannot avoid being outside when smoke levels are high, consider wearing a properly fitted N95 or P100 respirator to reduce exposure. Cloth and paper masks do not offer protection from fine particles, which are small enough to go through the mask. More effort is required to breath when wearing a respirator, so strenuous exercise or heavy exertion is not recommended when wearing one.

"Although N95 respirators can help with smoke exposure, ozone is a gas that is not blocked by these respirators, “ said Hayes. “Pay attention to ozone levels or just avoid exerting yourself outdoors in the afternoon or early evening on action alert days.”

The smoke and ozone levels we are seeing are caused by wildfire activity worsened by climate change and air pollution sources that cause climate change. Ozone on its own is invisible and is produced when volatile organic compounds (VOCs) mix with combustion emissions in the presence of sunlight. Boulder County's VOCs predominantly come from oil and gas operations to the northeast and combustion byproducts from vehicles.

“The health of all of our residents is at risk because of these conditions, but we’re particularly concerned about sensitive populations,” said Collin Tomb, Climate and Health Strategist for Boulder County. “This includes the elderly, children, those with lung and heart conditions, and disproportionately impacted communities that may already live closer to sources of air pollution, such as busy roadways or oil and gas operations. Community members who work outdoors or don’t have access to air-conditioned indoor spaces are also most at risk.”

“Boulder County is working hard to help Colorado reach ambitious climate and air quality goals by influencing and advocating for more aggressive policy at the state level, but we still have a long ways to go,” says Cindy Copeland, Boulder County Air and Climate Policy Analyst. “The good news is that there are steps we can take to reduce emissions and improve the situation. Plans are being considered to reduce emissions in the vehicle, oil and gas, power, and industrial sectors.”

Members of the public who are concerned about the effects of air pollution and climate change can make their voices heard by commenting in writing or orally to the state’s Air Quality Control Commission or the Regional Air Quality Council; specific comments on transportation emissions can be directed to the Transportation Commission or the Denver Regional Council of Governments.

For additional information about air quality and health, contact Bill Hayes, BCPH Air Quality Coordinator, at 303-441-1574 or

For additional information about Boulder County's sustainability and climate mission, contact Christian Herrmann at

Ozone pollution sources