Frequently Asked Questions
Have questions about air quality and ground-level ozone in the Colroado Front Range? You’re not alone! Take a read below for answers to some of our most frequently asked questions.
Ground-level ozone
What is ground-level ozone?
Ground-level ozone is an invisible, odorless air pollutant in our layer of the atmosphere that can reach levels harmful to our health in the summer months. It forms when volatile organic compounds (VOCs) and nitrogen oxides (NOx), react in the sunshine and heat that build up on summer days. These emissions come mainly from our gas-powered vehicles, lawn equipment, and oil and gas production.
I thought ozone was good for the atmosphere?
Ozone is simply three oxygen atoms stuck together. High up in the atmosphere, the ozone layer serves an important purpose: it protects us from the sun’s ultraviolet radiation. But at ground level, it’s a pollutant and high concentrations of ozone are toxic to people.
Why is ground-level ozone dangerous to our health?
- Animals (like humans, our pets, and wildlife) have lungs designed to breathe oxygen (O2) and not ozone (O3). When we breathe in ozone, it reacts with our lungs and causes inflammation and irritation, which is why you may feel a tightness in your chest or have other breathing difficulties outside on high ozone days.
- The American Lung Association likens breathing elevated levels of ozone pollution to getting a sunburn on your lungs. Exposure to high levels of ground-level ozone is linked to multiple health conditions, like asthma.
Why is ozone a concern in the Colorado Front Range?
The 9-county Colorado Front Range region has been experiencing high ozone levels for decades and is currently in nonattainment for ground-level ozone for two federal ozone standards.
What does “nonattainment” mean?
A nonattainment area is a region that fails to meet the National Ambient Air Quality Standards (NAAQS, rhymes with “snacks”) for one or more air pollutants outlined in the Clean Air Act. The length of time that a region has been in nonattainment determines its categorization: moderate, serious, severe, or extreme.
Still have questions? Check out our Air Quality 101 page.
air quality alerts
I want to sign up for summer ozone alerts. Where do I do that?
I want to unsubscribe from ozone alerts, how do I do that?
- To unsubscribe from text alerts, text “STOP” to 21000 or reply “STOP” to (877) 926-2470.
- To unsubscribe from email alerts, scroll down to the bottom of a recent alert email from us. Click the “unsubscribe” button and follow the instructions.
I also want to receive wildfire smoke and other air quality alerts. Do you send those?
- No, we only send text and email alerts for summer ozone. However, our alerts might reference wildfire smoke or other pollutants in the summer when they are impacting ozone levels.
- Learn what other air quality alerts are available for Coloradans on our resources page.
Still have questions? Check out our alerts sign up page.
FRONT RANGE AIR QUALITY
Is ozone our only outdoor air quality issue in the Colorado Front Range?
While ground-level ozone is our most pressing air quality issue, it is not our only one. In the summer months, we also might deal with wildfire smoke. In the winter months, the Denver metro can also experience higher levels of particulate air pollution.
I get air quality notifications in my weather app, on my phone, or from other sources. What are those about?
Other agencies and organizations can send air quality information directly to you. You may be signed up to receive text or emails, have apps downloaded that send you notifications, or use a device that automatically sends you air quality information from its weather app. These notifications may give you an overall picture of air quality at the moment, or focus on a specific pollutant. Many send information about the Air Quality Index, or AQI (see below).
What is the AQI?
The U.S. Air Quality Index (AQI) is EPA’s tool for communicating about outdoor air quality and health. It is a real-time calculation of air quality based on five air pollutants that are harmful to human health at higher levels. These pollutants include: ground-level ozone, particle pollution (also known as particulate matter, including PM2.5 and PM10), carbon monoxide, sulfur dioxide, and nitrogen dioxide. To learn more, visit: www.airnow.gov/aqi/.
Is ozone the same as Denver’s “brown cloud”?
- No, Denver’s “brown cloud” is an older term relating to various air pollution problems in the Denver metro that were a bigger problem about 40 to 50 years ago. While it’s still an important issue, it was significantly improved through the collaboration of residents, businesses, and government agencies.
- When people refer to Denver’s “brown cloud” today, they often are referring to the visible air pollution we have in the winter months, when denser, heavier cold air gets trapped under a blanket of warm air, known as an inversion. This temperature inversion concentrates pollutants closer to the ground, and results in the yellow-brown strip visible along the horizon. The pollution that creates this unsightly color is mainly from nitrogen oxides (NOx) and sulfur oxides (SOx), as well as tiny particles of grit,dust, and smoke (particulate matter).
Why is our gasoline different in the summer months?
Summers and winters in Colorado are both amazing — and very different! Seasonal fuel blends help reduce air pollution while ensuring we have the best type of gas for the season. Winter blends help your car start and run better in cold temperatures, but lead to increased pollution in hot temperatures. Summer blends help reduce evaporation and pollution in the hot summer months. Reformulated Gas (RFG) has not been shown to have a meaningful impact on fuel costs.
Still have questions? Check out our Air Quality 101 page or our blog.
simple steps
How do I recycle my old gas-powered lawn and garden equipment?
Each city and county may have different regulations and locations for how to recycle old gas-powered lawn and garden equipment. We recommend looking for this information on your city or county’s local government website.
How can I find a participating retailer to purchase discounted electric lawn equipment?
Thanks to a new law that went into effect on Jan. 1, 2024, Coloradans can save money and cut air pollution at the same time by enjoying a 30% discount on electric lawn mowers, leaf blowers, trimmers and snow blowers at participating retailers statewide. The Colorado Public Interest Research Group (CoPIRG) compiled a list of participating retailers. Please call a retailer in advance to confirm participation as companies may start or discontinue participation: https://pirg.org/colorado/foundation/resources/how-to-unlock-savings-with-colorados-new-electric-lawn-mower-tax-credit/
I’d like to help reduce vehicle idling in my community or at my child’s school. How can I do that?
Visit our Engines Off program website to learn more: www.enginesoff.org.
I’d like to repair my car and improve air quality, but don’t have the money or resources. Can you help?
CAAR (Clean Air Auto Repair) is a program run by the Regional Air Quality Council (RAQC) that aims to reduce air pollution by fixing high polluting vehicles, within the Denver Metropolitan and Colorado Front Range Area. The program provides financial support to eligible vehicle owners to repair their vehicles. By participating in CAAR, vehicle owners can help improve air quality in Colorado and get their vehicle back on the road! Learn more and see if you qualify: www.cleanairautorepair.org.
Still have questions? Check out our Simple Steps page.
reporting air quality issues
I smelled a really bad odor, how can I report that?
Colorado regulations limit how strong odors coming from certain types of agriculture and industry can be. To learn how to report an odor to the correct state authority, please visit: cdphe.colorado.gov/odors.
I saw a vehicle clearly violating emission standards / I saw a vehicle with smoke coming out of its tailpipe. How do I report that?
- The Colorado Smoking Vehicle Hotline program helps identify vehicles with excessive emissions, and gives owners of those vehicles information that will encourage them to voluntarily make needed repairs. Please visit the smoking vehicle hotline to learn more and make a report: cdphe.colorado.gov/motor-vehicle-emissions/smoking-vehicle-hotline-old
- To report an aggressive driver, dial *CSP (*277) or please visit: csp.colorado.gov/talk-with-us/report-an-aggressive-driver
I see smoke and/or want to know more about wildfire smoke, where can I find out more?
- The CDPHE Air Pollution Control Division periodically updates its Colorado Smoke Blog to provide information about smoke in Colorado. This page covers wildfire activity, prescribed burning operations, and the transport of smoke from out-of-state sources: colosmokeoutlook.blogspot.com/
- Watch Duty, a 501(c)(3) nonprofit, alerts you of nearby wildfires and firefighting efforts in real-time: app.watchduty.org/
AIR QUALITY & FILTRATION
I’m concerned about my indoor air quality at home or at work. How do I improve indoor air quality?
- Indoor air quality can be improved by adding to or improving air filtration. This may involve a building’s HVAC system, or it can be as easy as purchasing or building an affordable standalone air purifier. Learn more about improving indoor air quality at our blog: How to improve your indoor air quality
- For more information on selecting an indoor air filter, please visit the EPA’s website: www.epa.gov/indoor-air-quality-iaq/guide-air-cleaners-home#tips
Do you provide air purifiers or air filters?
No, the Regional Air Quality Council and Simple Steps. Better Air. do not provide supplies such as air purifiers or air filters to the general public.
Should I wear a mask outdoors for ozone?
- A face covering or mask does not help protect your lungs from ozone pollution.
- Most masks and respirators — such as surgical masks, cloth masks, KN95s, KN94s, and N95s — do not filter out ozone (O3) or other air pollution that are gases, like VOCs and NOx. Gases easily move through these types of filters — including oxygen and carbon dioxide — which is why we can breathe through them and they are safe to wear.
- High quality, well-fitted respirators such as KN95s, KN94s, and N95s, however, are great tools to use any time of year, indoors or outdoors for other reasons. They filter out wildfire smoke, particle pollution, and dust, help with allergies, and prevent the transmission of infectious disease, since they work by trapping tiny floating particles like smoke, soot, pollen, and saliva in their electrostatic fibers.
Still have questions? What you’re looking for may be available through our list of resources, or explained in our Air Quality 101 information.
