Compare Air Quality Between US Cities: City vs City AQI (2026)
Pick any two of 146 US cities and see which has cleaner air right now — latest EPA AirNow AQI, dominant pollutant (PM2.5 or ozone), and EPA health guidance side by side, with a plain verdict on the cleaner city. 354 city-vs-city matchups are ready to open below, or start from any city in the grid. Want the big picture first? See all US cities ranked by air quality, from today's cleanest to the most polluted.
If the city you live in (or are moving to) comes out worse, size a purifier for your room with our free CADR calculator — indoor air is the part you control.
Comparing cities? Look at annual averages for relocation decisions; use the latest observed AQI for day-to-day outdoor activity planning.
How do you compare air quality between two US cities?
Compare each city's latest EPA Air Quality Index on the same 0–500 scale — the lower AQI is the cleaner city right now. As of September 16, 2026, 146 US cities have a live reading here, from Omaha, NE (AQI 10) to Little Rock, AR (AQI 96), and 354 city-vs-city pages are pre-built.
- ✓Lower AQI wins: 0–50 Good, 51–100 Moderate, above 100 affects sensitive groups
- ✓Example today: San Francisco beats Seattle by 1 AQI points (36 vs 37)
- ✓Each comparison shows both cities' dominant pollutant — ozone (hot afternoons) vs PM2.5 (smoke, winter inversions)
- ✓Use today's AQI for outdoor plans; use annual patterns for relocation decisions
Frequently asked questions
How do I do an air quality comparison between two cities?▾
Pick a matchup from the Popular Comparisons cards, or click any city in the Compare Any Cities grid and choose a second city from its page. Each city-vs-city page shows both cities' latest EPA AirNow AQI, the dominant pollutant (usually ozone or PM2.5), EPA health guidance, and a verdict on which city has cleaner air right now. The lower AQI is always the cleaner city.
Which city has cleaner air today — San Francisco or Seattle?▾
As of September 16, 2026, San Francisco, CA has cleaner air: AQI 36 (Good) for San Francisco vs AQI 37 (Good) for Seattle — a gap of 1 AQI points in the latest EPA AirNow observations.
How big an AQI difference between two cities actually matters?▾
Judge the gap by EPA category, not raw points. Two cities both in the Good range (0–50) are effectively equal for outdoor plans. The differences that matter are threshold crossings: 51–100 (Moderate) starts to affect very sensitive people, and above 100 (Unhealthy for Sensitive Groups) is where asthma, heart-disease and older-adult guidance kicks in for the higher-AQI city. For relocation decisions, compare how often each city crosses 100 over a year rather than one day's reading.
How many US cities can I compare here?▾
146 US cities have a live EPA AirNow reading this update, and 354 city-vs-city comparison pages are pre-built. Right now the cleanest tracked city is Omaha, NE (AQI 10) and the most polluted is Little Rock, AR (AQI 96).
Popular Comparisons
Latest AQI observation for each city — lower is cleaner. Sourced from EPA AirNow.
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Compare Any Cities
Click any city below to see comparisons with other cities.
How to Compare Air Quality Between Two Cities
The fastest way to compare two cities is the Air Quality Index (AQI) — a single 0–500 scale that rolls every major pollutant into one number, so a reading in one city means the same thing as a reading in another. Lower is always cleaner: 0–50 is Good (healthy for everyone), 51–100 is Moderate (fine for most, a minor concern for sensitive groups), and anything above 100starts to affect sensitive people. The city with the lower AQI right now has the healthier air right now.
But one snapshot rarely tells the whole story, because the headline AQI reflects whichever pollutant is worst at that moment. Two cities can post the same AQI for very different reasons: a Western city like Los Angeles or Phoenix is usually driven by ozone, which peaks on hot, sunny afternoons, while a dense Eastern or Midwestern city is more often driven by PM2.5 (fine particles from traffic, industry, and wood smoke), which tends to be worse in winter and overnight. When two cities are close, check which pollutant is leading in each — that tells you when each city's air is likely to be unhealthy.
Match the metric to your decision. For day-to-day plans — whether it's safe air quality to run in, a kid's sports game, or whether to open the windows — use the latest AQI shown on each comparison card above, since air quality can swing within hours. For a relocation or long-term decision, weigh the annual averages and seasonal patterns instead: a city with a slightly higher reading today but far fewer bad-air days over the year is the cleaner place to live. Wildfire season is the big wildcard — a normally pristine Pacific Northwest city can spike into the "Unhealthy" range for days, so look at how each city behaves across a full year, not just on the afternoon you happen to check.
Frequently Asked Questions
What does comparing AQI between cities tell me?
Comparing Air Quality Index (AQI) values shows which city currently has healthier air. An AQI under 50 is "Good" for everyone; 51–100 is "Moderate" and may affect sensitive groups. Side-by-side comparisons help with travel planning, relocation research, and understanding regional pollution differences.
Which has better air quality — Los Angeles or New York?
It varies by season and time of day, but New York City generally records lower annual PM2.5 than Los Angeles. LA is prone to ozone and wildfire smoke, while NYC faces periodic traffic and industrial pollution spikes. Check the New York vs Los Angeles comparison for the latest readings.
Which US cities have the cleanest air quality?
Cities in the Pacific Northwest (outside wildfire season), Hawaii, and parts of the Northeast consistently rank among the cleanest. See our cleanest cities ranking for the current top 25. For the other end of the spectrum, see the most polluted cities in the US — America's 50 worst air quality cities in the latest EPA AirNow observations.
How often is the comparison data updated?
All AQI data comes from EPA AirNow monitoring stations and refreshes every hour. For the most accurate reading before outdoor activities, check the live city page or the full rankings table.
How does Denver's air quality compare to other Western US cities?
Denver, CO typically records moderate AQI levels driven by ground-level ozone on sunny afternoons and occasional wildfire smoke from the Mountain West. Compared to Phoenix (which has higher dust and heat-driven ozone) and Los Angeles (chronic ozone and PM2.5), Denver generally fares better on average — though Front Range inversions can trap pollution in winter. For a live side-by-side, see the Denver vs Phoenix comparison or check Denver's current AQI from EPA AirNow data.
Which has better air quality — Portland or Seattle?
Portland, OR and Seattle, WA both enjoy clean air most of the year, but Portland typically scores slightly worse annually due to its geography (the Willamette Valley traps pollution) and greater wildfire smoke exposure in late summer. Seattle benefits from Puget Sound breezes that disperse pollutants more consistently. Both cities can spike into "Unhealthy" range during wildfire season. See the live Portland vs Seattle air quality comparison for today's AQI data from EPA AirNow.