What Is the Air Quality in Mesa, Colorado?
Mesa, Colorado has an Air Quality Grade of B (good) with a 5-year median AQI of 45. The dominant pollutant is Ground-Level Ozone, and air quality has been improving over the past decade.
Mesa, Colorado Air Quality Snapshot
| Air Quality Grade | B66/100 |
| 5-Year Median AQI | 45 (Good) |
| Most Recent Median AQI (2023) | 46 (Good) |
| Dominant Pollutant | Ground-Level Ozone |
| 10-Year Trend | Improving (-0.39 AQI/yr) |
| Unhealthy Days (last 5 yr) | 7 |
| National Rank (cleanest = #1) | #783 of 1,020 (77th most polluted percentile) |
| Colorado Rank | #13 of 32 |
What Does the B Grade Mean?
Mesa, Colorado earns a B — air quality is reliably in the safe range for most residents most of the time, with a 5-year median AQI of 45. Sensitive groups will see occasional caution days, but the typical resident will not need to change behavior based on air quality.
Mesa, Colorado's 5-year median AQI of 45 is 4 points above the national average of 41 — meaningfully more polluted than the typical U.S. metro tracked here. Within Colorado, Mesa, Colorado runs more polluted than the state average of 39 — local sources or geography are concentrating pollution above the state's typical reading.
For context within Colorado: Alamosa, Colorado currently holds the state's cleanest grade (A, AQI 14), while Jefferson, Colorado sits at the bottom (D, AQI 47).
What's in Mesa, Colorado's Air?
The dominant pollutant in Mesa, Colorado is Ground-Level Ozone. Ground-level ozone forms when sunlight reacts with vehicle exhaust and industrial emissions. It is worst on hot, sunny, stagnant summer days. Ozone irritates the lungs, triggers asthma attacks, and reduces lung function — even healthy adults can feel chest tightness and shortness of breath after exercising in elevated ozone.
Days by Dominant Pollutant (2023)
| Pollutant | Days as Dominant | Share of Year |
|---|---|---|
| Ground-Level Ozone | 301 | 82% |
| Fine Particulate Matter (PM2.5) | 64 | 18% |
Is the Air Getting Better or Worse?
Air quality in Mesa, Colorado has been improving over the past decade, with median AQI dropping by roughly 0.4 points per year. That is consistent with the broader national pattern — most U.S. metros have seen steady reductions in particulate and ozone pollution since the 2010s as cleaner vehicles and power plants come online.
In 2014, Mesa, Colorado posted a median AQI of 48. By 2023 that figure was 46 — a drop of 2 AQI points cleaner across 10 years of EPA records.
Year-by-Year AQI in Mesa, Colorado
| Year | Median AQI | Good Days | Unhealthy Days | Dominant Pollutant |
|---|---|---|---|---|
| 2014 | 48 | 216 | 1 | Ozone |
| 2015 | 48 | 225 | 3 | Ozone |
| 2016 | 47 | 245 | 1 | Ozone |
| 2017 | 48 | 213 | 1 | Ozone |
| 2018 | 49 | 193 | 5 | Ozone |
| 2019 | 47 | 238 | 1 | Ozone |
| 2020 | 44 | 262 | 3 | Ozone |
| 2021 | 46 | 247 | 2 | Ozone |
| 2022 | 44 | 282 | 1 | Ozone |
| 2023 | 46 | 246 | 0 | Ozone |
Health Context for Mesa, Colorado
Across the past five years, this area has logged just 7 days where AQI rose into the "Unhealthy for Sensitive Groups" range or worse — about 1 days per year, or roughly one every other month. That is a low count by national standards.
For most healthy adults, current air quality in this area does not require any change in behavior. People with severe asthma, COPD, or recent cardiac events should still keep an eye on daily AQI alerts, especially during wildfire season. Because ozone peaks in the afternoon on hot sunny days, plan outdoor exercise for early morning or after sunset on bad-air days.
How This Grade Is Calculated
The AirHistory Air Quality Grade combines four signals: the 5-year median AQI (40% of the score), the 10-year trend direction (30%), the count of unhealthy days per year (20%), and the dominant pollutant type (10%). All four come directly from the EPA Air Quality System (AQS), which aggregates readings from federally certified monitors. Read the full methodology.
Mesa, Colorado has an Air Quality Grade of B (good) with a 5-year median AQI of 45. The dominant pollutant is Ground-Level Ozone, and air quality has been improving over the past decade.
This answer pulls from the EPA Air Quality System (AQS), the authoritative federal source for U.S. air quality and pollution monitoring. The headline number above is the direct answer; what follows is the additional context most readers need to use the answer for a real decision rather than just a fact lookup.
A practical caveat: the headline answer above reflects the most recent the EPA Air Quality System (AQS) vintage; underlying data is often revised for months after first publication, and the right reference for any specific decision is whichever vintage is current at the time of the decision. The as-of date is stamped on every page.
Source: EPA Outdoor Air Quality Data, 2026.