Air Pollution

What is air pollution?

Air pollution is a mix of hazardous substances from both man-made and natural sources. Vehicle emissions, fuel oils and natural gas to heat homes, by-products of manufacturing and power generation, particularly coal-fueled power plants, and fumes from chemical production are the primary sources of human-made air pollution.

Frequently Asked Questions

Like much of the country, the primary air pollutants of concern in Utah are ground-level ozone and particulate matter (PM). Levels of these pollutants can vary by season, with ozone higher in the summer and PM higher during the winter.

Noxious gases
- Noxious gases, which include carbon dioxide, carbon monoxide, volatile organic compounds (VOCs), nitrogen oxides (NOx), and sulfur oxides (SOx), are components of motor vehicle emissions and byproducts of industrial processes.
Ozone
- Ozone (O3) is an atmospheric gas, which is often called smog when at ground level. It is created when the pollutants NOx and VOCs emitted by cars, power plants, industrial boilers, refineries, and other sources chemically react in the presence of sunlight. It is one of the six EPA criteria pollutants.
PM
- Particulate matter (also called PM or particle pollution) is a complex airborne mixture of solid particles and liquid droplets. It is composed of chemicals such as sulfates, nitrates, carbon, or mineral dusts. Vehicle and industrial emissions from fossil fuel combustion, cigarette smoke, and burning organic matter, such as wildfires, all contain PM.Though PM ranges widely in size, it has been divided into two categories based on diameter.
  - PM_2.5: Particles with a diameter smaller than 2.5 micrometers (µm, or microns)
  - PM₁₀: Particles with a diameter between 2.5 µm and 10 µm
Lead
- Lead is a toxic heavy metal that can be found in all parts of our environment, partly due to human activities. Major sources of lead in the air include ore and metals processing and piston-engine aircraft operating on leaded aviation fuel. Other sources are waste incinerators, utilities, and lead-acid battery manufacturers. The highest air concentrations of lead are usually found near lead smelters. Once released into the air it may travel long distances before it settles to the ground, where it usually binds strongly to soil particles.

The majority of Utah's population lives along the Wasatch Front. During the winter, the valleys in this region also experience what are known as temperature inversions, where a layer of warmer air traps air near the ground and prevents mixing. This traps pollutants from vehicle emissions and industrial activities. Furthermore, sunlight converts the hydrocarbons and nitrogen oxides present in these trapped pollutants into harmful ozone, which reduces air quality.

Local air quality can change from day to day. EPA developed the Air Quality Index, or AQI, to make information available about the health effects of the most common air pollutants, and how to avoid those effects. Check your local AQI on the Utah DEQ’s website or the AirNow website and use the chart below to help reduce your exposure and protect your health.

**AQI Basics for Ozone and Particle Pollution**
Daily AQI Color	Levels of Concern	Values of Index	Description of Air Quality
Green	Good	0 to 50	Air quality is satisfactory, and air pollution poses little or no risk.
Yellow	Moderate	51 to 100	Air quality is acceptable. However, there may be a risk for some people, particularly those who are unusually sensitive to air pollution.
Orange	Unhealthy for Sensitive Groups	101 to 150	Members of sensitive groups may experience health effects. The general public is less likely to be affected.
Red	Unhealthy	151 to 200	Some members of the general public may experience health effects; members of sensitive groups may experience more serious health effects.
Purple	Very Unhealthy	201 to 300	Health alert: The risk of health effects is increased for everyone.
Maroon	Hazardous	301 and higher	Health warning of emergency conditions: everyone is more likely to be affected.

**Air Quality Guide for Particle Pollution**
Harmful particle pollution is one of our nation's most common air pollutants. Use the chart below to help reduce your exposure and protect your health. For your local air quality, visit www.airnow.gov.
Air Quality Index	Who Needs to be Concerned?	What Should I Do?
Good (0-50)		It's a great day to be active outside.
Moderate (51-100)	Some people who may be unusually sensitive to particle pollution.	Unusually sensitive people: Consider reducing prolonged or heavy exertion. Watch for symptoms such as coughing or shortness of breath. These are signs to take it easier. Everyone else: It’s a good day to be active outside.
Unhealthy for Sensitive Groups (101-150)	Sensitive groups include people with heart or lung disease, older adults, children and teenagers.	Sensitive groups: Reduce prolonged or heavy exertion. It’s OK to be active outside, but take more breaks and do less intense activities. Watch for symptoms such as coughing or shortness of breath. People with asthma should follow their asthma action plans and keep quick relief medicine handy. If you have heart disease: Symptoms such as palpitations, shortness of breath, or unusual fatigue may indicate a serious problem. If you have any of these, contact your heath care provider.
Unhealthy (151-200)	Everyone	Sensitive groups: Avoid all physical activity outdoors. Move activities indoors or reschedule to a time when air quality is better. Everyone else: Avoid prolonged or heavy exertion. Consider moving activities indoors or rescheduling to a time when air quality is better.
Very Unhealthy (201-300)	Everyone	Sensitive groups: Avoid all physical activity outdoors. Move activities indoors or reschedule to a time when air quality is better. Everyone else: Avoid prolonged or heavy exertion. Consider moving activities indoors or rescheduling to a time when air quality is better.
Hazardous (301-500)	Everyone	Everyone: Avoid all physical activity outdoors. Sensitive groups: Remain indoors and keep activity levels low. Follow tips for keeping particle levels low indoors.

**Air Quality Guide for Ozone**
Ground-level ozone is one of our nation's most common air pollutants. Use the chart below to help reduce your exposure and protect your health. For your local air quality, visit www.airnow.gov.
Air Quality Index	Who Needs to be Concerned?	What Should I Do?
Good (0-50)		It's a great day to be active outside.
Moderate (51-100)	Some people who may be unusually sensitive to ozone.	Unusually sensitive people: Consider reducing prolonged or heavy outdoor exertion. Watch for symptoms such as coughing or shortness of breath. These are signs to take it easier. Everyone else: It’s a good day to be active outside.
Unhealthy for Sensitive Groups (101-150)	Sensitive groups include people with lung disease such as asthma, older adults, children and teenagers, and people who are active outdoors.	Sensitive groups: Reduce prolonged or heavy outdoor exertion. Take more breaks, do less intense activities. Watch for symptoms such as coughing or shortness of breath. Schedule outdoor activities in the morning when ozone is lower. People with asthma should follow their asthma action plans and keep quick relief medicine handy.
Unhealthy (151-200)	Everyone	Sensitive groups: Avoid prolonged or heavy outdoor exertion. Schedule outdoor activities in the morning when ozone is lower. Consider moving activities indoors. People with asthma, keep quick-relief medicine handy. Everyone else: Reduce prolonged or heavy outdoor exertion. Take more breaks, do less intense activities. Schedule outdoor activities in the morning when ozone is lower.
Very Unhealthy (201-300)	Everyone	Sensitive groups: Avoid all physical activity outdoors. Move activities indoors or reschedule to a time when air quality is better. People with asthma, keep quick-relief medicine handy. Everyone else: Avoid prolonged or heavy outdoor exertion. Schedule outdoor activities in the morning when ozone is lower. Consider moving activities indoors.
Hazardous (301-500)	Everyone	Everyone: Avoid all physical activity outdoors.

Note: If you don't have an air conditioner, staying inside with the windows closed may be dangerous in extremely hot weather. In these cases, seek alternative shelter.

Below, you can see the effect of an inversion: the left side shows a day with very low levels of PM, while the right side shows a day three weeks later during an inversion with higher levels of PM_2.5.

Wildfire Smoke

Frequently Asked Questions

Wildfire smoke is made up of a mixture of gases and fine particles produced when wood and other organic materials burn. The biggest health threat from smoke is from fine particles. These microscopic particles can be inhaled deep into your lungs. Smoke can also irritate your eyes and your respiratory system, and worsen chronic heart and lung diseases. The amount and length of smoke exposure, as well as a person’s age and degree of susceptibility, play a role in determining whether someone will experience smoke-related health problems.

Smoke may worsen symptoms for people who have pre-existing health conditions and those who are particularly sensitive to air pollution. Sensitive groups include:

People with asthma or other chronic respiratory disease
People with respiratory infections
People with cardiovascular disease
People ≥ 65 years of age
People with diabetes
Infants and children
Pregnant woman
Smokers, especially those who have smoked for several years

High concentrations of smoke can cause a range of health problems, including:

Burning eyes, a runny nose, cough, phlegm, wheezing, chest pain, and difficulty breathing.
If you have heart or lung disease, smoke may make your symptoms worse.
People with heart disease might experience chest pain, palpitations, shortness of breath, or fatigue.
People with lung disease may not be able to breathe as deeply or as vigorously as usual, and may experience symptoms such as coughing, phlegm, chest discomfort, wheezing and shortness of breath.

Limit your exposure to the smoke:

Stay indoors whenever possible and keep indoor air clean by closing doors and windows.
Avoid physical activities outdoors if smoke is in the air.
Avoid activities that create more indoor pollution, such as frying foods, sweeping, vacuuming, burning candles, smoking and using gas-powered appliances.
Use a portable air cleaner with a high-efficiency (HEPA) air-cleaning filters.
- Choose quality air cleaning technologies that do not create ozone.
- How to Choose a Portable Air Cleaner - CEHN
Use a do-it-yourself HEPA-filter box fan (Español).
Drink plenty of water to help reduce symptoms of scratchy throat and coughing.
Monitor the air quality conditions in your area at air.utah.gov
Consider leaving the area if air quality is poor and it’s not possible to keep indoor air clean, especially for those who have health conditions.

Indoor Air Quality

Indoor Air Quality (IAQ) refers to the air quality within and around buildings and structures, especially as it relates to the health and comfort of building occupants. The average person spends up to 90 percent of their time inside. Poor indoor air quality can cause similar health effects as exposure to outdoor pollution such as: decreased lung size and function, acute respiratory illnesses (such as asthma and bronchitis), emphysema, and even some types of cancer.

Frequently Asked Questions

Indoor air pollution levels are often 2-5 times greater than outdoor levels as a result of indoor contaminants, inadequate air filtration, and ventilation. Cooking, fuel burning combustion appliances, tobacco products, building materials and furnishings, cleaning and disinfecting products, central heating and cooling systems, excess moisture, outdoor sources like radon, pesticides, and outdoor air pollution all contribute to poor IAQ.

A person’s risk of experiencing health effects from air pollution varies depending on their age, where they live, underlying health conditions, and other factors. People most at risk of health problems related to indoor air pollution include:

People with lung diseases, such as asthma, chronic bronchitis, emphysema, and chronic obstructive pulmonary disease(COPD)
Infants and young children
Adults older than 65
People with a cardiovascular disease
People who smoke or are exposed to second-hand smoke

On poor air days, keep doors and windows shut to keep pollutants out.
Open windows and doors to increase airflow, when outdoor air quality is good.
Do not use scented or unscented candles, artificial air fresheners, or products with fragrances.
Optimize heat, ventilation, and air conditioning (HVAC) systems.
Use a portable air cleaner with a high-efficiency (HEPA) air-cleaning filters.
- Choose quality air cleaning technologies that do not create ozone.
- How to Choose a Portable Air Cleaner - CEHN
A home-made HEPA-box fan filter (Español) is an excellent ventilation alternative.
Avoid activities that create more indoor pollution, such as frying foods, sweeping, vacuuming, burning candles, smoking and using gas-powered appliances.

WestSide Airsense: Empowering communities through enchanced PM monitoring

Utah APPLETREE has partnered with the University of Utah and the Department of Environmental Quality's Division of Air Quality to learn more about particulate matter (PM) in underserved neighborhoods on the west side of the Salt Lake Valley. The team will be using affordable air quality sensors in those areas to measure levels of PM2.5 and PM10 particles.

We are developing air quality maps and alerts to provide instant, local air quality information. Interested community members can get involved and will be compensated for their time. Community input will also help inform air quality sensors’ placement. Outreach modules on particulate pollution and its impact on local air quality will also be available for use by educators and other interested community members.

If you would like to be involved in this project, please visit: Westside Air: Get Involved

This project will be completed in May 2026 and updates will be shared here and in the WestSide AirSense newsletter.

To sign up for the newsletter please visit: WestSide Airsense