Air quality index (AQI⁺) and PM2.5 air pollution in Utah •
When air quality in your area reaches unhealthy levels, we'll send you a quick alert, along with expert tips on how to reduce your exposure.
Real-time most polluted cities in Utah
Real-time cleanest cities in Utah
When outdoor air quality drops, the EPA recommends upgrading to a MERV 13 filter — or the highest-rated filter your HVAC system can handle — to help capture more of the fine particulate (PM2.5) that comes with poor air quality. MERV 13 is the highest rating most residential systems can run without restricting airflow.
AQI stands for Air Quality Index, the EPA's scale for reporting daily air quality. It runs from 0 to 500. The higher the number, the greater the level of air pollution. Values at or below 100 are generally considered satisfactory; values above 100 mean air quality is unhealthy, first for sensitive groups, then for everyone as numbers climb.
The AQI tracks five major pollutants regulated by the Clean Air Act: ground-level ozone, particle pollution (PM2.5 and PM10), carbon monoxide, sulfur dioxide, and nitrogen dioxide. The reported AQI value reflects whichever pollutant is highest at that time — most often ozone or fine particles (PM2.5).
Monitoring stations measure pollutant concentrations, and the EPA converts each into a standardized 0–500 score using set breakpoints. Each pollutant gets its own sub-index, and the highest sub-index becomes the reported AQI. That's why a single number can represent different pollutants on different days.
An AQI of 0–50 is rated "Good" — air quality poses little or no risk. 51–100 is "Moderate," acceptable for most people though unusually sensitive individuals may want to limit prolonged outdoor exertion. Anything at or below 100 is generally considered satisfactory air quality.
100 is the dividing line: at or below it, air quality is satisfactory for the general public. From 101–150, air is "Unhealthy for Sensitive Groups" — people with respiratory conditions, older adults, and children. From 151–200, it's "Unhealthy" and everyone may begin to feel effects.
Short-term AQI spikes usually come from wildfire smoke, temperature inversions that trap pollutants near the ground, high-ozone weather (hot, sunny, stagnant days), or heavy traffic and industrial activity. Check a real-time source like the map on this page to see which pollutant is driving today's reading in your area.
Many runners follow the EPA category lines: below 50, no adjustment needed; 51–100, unusually sensitive people may shorten intense workouts; above 100, sensitive groups are advised to reduce prolonged or heavy outdoor exertion; above 150, that advice extends to everyone. Exercise increases how much air you breathe in, which is why thresholds matter more during workouts.
A common rule of thumb is to keep windows open when the AQI is under 100 and close them when it climbs above, especially during wildfire smoke events when fine particles are elevated. When windows are closed, running your HVAC system with a fresh filter helps capture particles circulating indoors.
Public health agencies generally suggest considering a well-fitted N95-style respirator outdoors when the AQI exceeds 150, particularly during smoke events. Cloth and surgical masks don't filter fine particles effectively. Follow guidance from your local health department, which may adjust recommendations during severe episodes.
Use the live AQI map to see outdoor air conditions in your part of Utah. Check the reading and color for your town, then plan time outside or focus on indoor air as needed.
Utah’s live AQI map gives a quick view of outdoor air for your neighborhood and helps you time outdoor plans.
Inversions, summer ozone, wildfire smoke, and dust events are the main drivers of higher readings across the state.
Simple steps at home and outside reduce exposure on bad air days, and a clean, suitable Filterbuy filter helps keep indoor air more comfortable.
Open the map and look up your town or ZIP. Lower readings and cooler colors mean cleaner air. Higher readings and warmer colors mean more pollution. If the number rises during the day, keep outdoor time shorter or move hard activity indoors, especially for people with asthma, COPD, or heart disease, and for young children and older adults.
Winter temperature inversions along the Wasatch Front can trap fine particles near the ground until a storm clears the valley.
Summer heat and sunshine can raise ozone in the afternoon, especially along busy corridors.
Dry and windy periods can lift dust from open land and the Great Salt Lake lakebed, which has documented health impacts.
In winter, calm air often holds pollution close to neighborhoods until a storm mixes the air.
Spring brings windy days and dust events in open areas.
Summer heat increases afternoon ozone across parts of the Wasatch Front.
The Central Wasatch Commission’s Environmental Dashboard shows that fine-particle pollution (PM2.5) was generally higher in the early 2000s and has trended lower in more recent years, with one of the cleanest years in the late 2010s. Ozone tends to peak in summer and stay lower in cooler months. Year-round ozone tracking began in the mid-2000s, which makes these seasonal patterns easier to see.
The article also notes recent population growth that adds pressure from travel, housing, and construction. As of July 1, 2023, Utah’s population was 3,456,482, up 55,989 from 2022. These growth factors, combined with winter inversions and seasonal smoke, help explain why Salt Lake Valley still sees visible haze on some days even as long-term PM2.5 averages have improved.
Use the map like a weather check. Look in the morning before errands, outdoor work, or exercise, and recheck if wind shifts, heat builds, or smoke shows up in the forecast. If you work outside, glance again at midday so you can move heavy tasks earlier or later. If your route looks worse than your neighborhood, choose a different path or wait until conditions improve.
Small changes help. Keep hard exercise shorter and take more breaks. Choose parks and paths away from heavy traffic. Drink water and rest in shade or an indoor space when you can. If coughing, chest tightness, or shortness of breath starts, move activity indoors and rest.
Keep spare HVAC filters on hand and know the highest MERV your system allows.
Choose one cleaner room and be ready to run a portable air cleaner there.
Learn “recirculate” settings on your home system and in your car.
Watch wind and smoke forecasts along with the live AQI map.
Plan safe cooling options if closing windows could make the home too warm.
When the air improves, a short cleanup lowers indoor particles faster. Wipe hard surfaces with a damp cloth or microfiber. Vacuum carpets and rugs with a HEPA type vacuum if you have one. Wash bedding and throw blankets. Let the HVAC fan run for a few hours with a clean filter, then check the filter and replace it if it looks loaded.
Choose MERV 8 for everyday dust and larger pollen and to keep the system cleaner.
Use MERV 11 if you have pets or mild allergies and want better capture of small particles like dander and many mold spores.
Upgrade to MERV 13 for finer particles in smoke and urban haze, but only if your system is rated for higher efficiency.
Filterbuy provides U.S. made pleated filters in many standard and custom sizes so the filter seats properly and reduces air bypass. The synthetic media captures more than basic fiberglass and still supports airflow when changed on time. Many homes replace filters every one to three months. Orders ship fast with free shipping in the continental United States, and Auto Delivery helps you stay on schedule.
A live map that shows current outdoor air conditions for your location with one number and a matching color.
Check in the morning before outdoor plans. Recheck later if wind shifts, heat builds, or smoke is in the forecast.
Cold, calm air can trap pollution in the valleys during inversions, so particles build up until a storm mixes the air.
Heat and sun can raise ozone in the afternoon, and regional wildfire smoke can add fine particles on dry days.
Wind can lift dust from exposed lakebed and open land, which adds particles to nearby communities.
Keep outdoor sessions shorter or move hard workouts indoors. Sensitive groups should be extra careful.
Close windows during the worst hours, use recirculation on AC or HVAC, avoid indoor smoke, and run a portable air cleaner if you have one.
Start with MERV 8 for everyday dust. Use MERV 11 for pets or mild allergies. Choose MERV 13 for finer particles like smoke only if your system is rated for it.
Many homes change filters every one to three months. Check more often during long heating or cooling periods or during smoke events.
