Aurora, CO Air Quality in May
Across 2019–2025, Aurora's May air quality had a median AQI of 74 (Moderate) over 217 monitored days in the Denver-Aurora-Lakewood, CO area. 7.4% of May days (16 of 217) reached Unhealthy for Sensitive Groups or worse, and ground-level ozone set the daily AQI on 93.1% of days. The cleanest May on record here was 2021 (median AQI 64, 1 day above 100) and the worst was 2023 (median 80, 4 days above 100, peak AQI 179).
- Good: 10.1%
- Moderate: 82.5%
- Unhealthy for Sensitive Groups: 6.5%
- Unhealthy or worse: 0.9%
Reduce Indoor Ozone in Aurora
Today's main pollutant in Aurora is ground-level ozone (AQI 43). Important: standard HEPA filters do NOT remove ozone — only a purifier with a substantial activated-carbon bed adsorbs it. The biggest wins are cutting indoor sources (gas appliances, certain "ionizer" purifiers) and ventilating when outdoor ozone is low (early morning). A high-carbon unit helps with the gases and VOCs that linger indoors.
Recommended: Levoit Core 300 — True HEPA + activated carbon · CADR ~141 CFM · rooms up to 219 sq ft
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How is the air in Aurora in May?
Moderate on a typical day: median AQI 74 across 2019–2025, with 7.4% of May days above AQI 100. Ground-level ozone is the main driver.
- ✓10.1% of May days were Good (AQI 0–50), 82.5% Moderate (51–100).
- ✓16 days of 217 reached AQI 101+; the May peak was 179.
- ✓Best May: 2021; worst May: 2023.
Frequently asked questions
What is the air quality like in Aurora in May?▾
Across 2019–2025, the median daily AQI in Aurora in May was 74 (Moderate). 10.1% of days were Good, 82.5% Moderate, and 7.4% reached Unhealthy for Sensitive Groups or worse, based on 217 monitored days in EPA's Air Quality System.
Is May a good time for outdoor exercise in Aurora?▾
A typical May day in Aurora is Moderate (median AQI 74): outdoor exercise is acceptable for most people, but unusually sensitive individuals should watch for symptoms, and about 1 day in 14 of May days (7.4%) reached AQI 101+ — the level at which EPA advises people with asthma, children and older adults to shorten hard outdoor exertion.
Which pollutant causes Aurora's May air quality problems?▾
Ground-level ozone set the daily AQI on 93.1% of May days in Aurora. The highest May AQI recorded in 2019–2025 was 179 (Unhealthy), in 2023.
Aurora May air quality, year by year
Aurora May air quality by year (Denver-Aurora-Lakewood, CO, EPA AQS daily AQI)
| Year | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| 2019 | 31 | 77 | 2 | 101 | O3 |
| 2020 | 31 | 74 | 1 | 105 | O3 |
| 2021cleanest | 31 | 64 | 1 | 112 | O3 |
| 2022 | 31 | 64 | 1 | 122 | O3 |
| 2023worst | 31 | 80 | 4 | 179 | O3 |
| 2024 | 31 | 84 | 3 | 133 | O3 |
| 2025 | 31 | 71 | 4 | 115 | O3 |
What May air means in Aurora
A typical May day in Aurora is Moderate (median AQI 74): outdoor exercise is acceptable for most people, but unusually sensitive individuals should watch for symptoms, and about 1 day in 14 of May days (7.4%) reached AQI 101+ — the level at which EPA advises people with asthma, children and older adults to shorten hard outdoor exertion.
May's median AQI of 74 is above Aurora's whole-year median of 64, making it one of the area's dirtier periods. Nationally, the median May AQI across every EPA metro area (104,064 metro-days, 2019–2025) is 44, so Aurora runs above the national May norm; 7.4% of its May days topped AQI 100 versus 1.3% nationally (above average).
May is part of Aurora's spring season (March, April, May); the spring page pools all three months.
Activity-specific thresholds: running, cycling, kids' sports.
Right now in Aurora
The latest EPA AirNow observation puts Aurora's AQI at 43 (O3). The figures above are multi-year month statistics, not today's reading.
View current Aurora air quality →Source: EPA Air Quality System (AQS) pre-generated Daily AQI by CBSA files — daily AQI by CBSA (Denver-Aurora-Lakewood, CO), 2019–2025. Daily AQI per CBSA is the highest AQI reported by any monitor in the area that day; the defining parameter is the pollutant that set it. Month and season statistics pool every such day in the period across all years listed. Retrieved 2026-09-09.