Durham Air Quality in May
Across 2019–2025, Durham's May air quality had a median AQI of 45 (Good) over 217 monitored days in the Durham-Chapel Hill, NC area. 0.0% of May days (0 of 217) reached Unhealthy for Sensitive Groups or worse, and ground-level ozone set the daily AQI on 60.4% of days. The cleanest May on record here was 2020 (median AQI 37, 0 days above 100) and the worst was 2022 (median 47, 0 days above 100, peak AQI 77).
- Good: 69.6%
- Moderate: 30.4%
- Unhealthy for Sensitive Groups: 0.0%
- Unhealthy or worse: 0.0%
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How is the air in Durham in May?
Good on a typical day: median AQI 45 across 2019–2025, with 0.0% of May days above AQI 100. Ground-level ozone is the main driver.
- ✓69.6% of May days were Good (AQI 0–50), 30.4% Moderate (51–100).
- ✓0 days of 217 reached AQI 101+; the May peak was 90.
- ✓Best May: 2020; worst May: 2022.
Frequently asked questions
What is the air quality like in Durham in May?▾
Across 2019–2025, the median daily AQI in Durham in May was 45 (Good). 69.6% of days were Good, 30.4% Moderate, and 0.0% 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 Durham?▾
A typical May day in Durham sits in the Good range (median AQI 45), so running, cycling and children's outdoor play are fine for everyone on most days; fewer than 1% of May days reached AQI 101+ in 2019–2025.
Which pollutant causes Durham's May air quality problems?▾
Ground-level ozone set the daily AQI on 60.4% of May days in Durham. The highest May AQI recorded in 2019–2025 was 90 (Moderate), in 2022.
Durham May air quality, year by year
Durham May air quality by year (Durham-Chapel Hill, NC, EPA AQS daily AQI)
| Year | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| 2019 | 31 | 47 | 0 | 80 | O3 |
| 2020cleanest | 31 | 37 | 0 | 57 | O3 |
| 2021 | 31 | 47 | 0 | 90 | O3 |
| 2022worst | 31 | 47 | 0 | 77 | O3 |
| 2023 | 31 | 45 | 0 | 58 | O3 |
| 2024 | 31 | 46 | 0 | 71 | PM2.5 |
| 2025 | 31 | 44 | 0 | 57 | O3 |
What May air means in Durham
A typical May day in Durham sits in the Good range (median AQI 45), so running, cycling and children's outdoor play are fine for everyone on most days; fewer than 1% of May days reached AQI 101+ in 2019–2025.
May's median AQI of 45 is in line with Durham's whole-year median of 44, so this period is neither a clean nor a dirty stretch for the area. Nationally, the median May AQI across every EPA metro area (104,064 metro-days, 2019–2025) is 44, so Durham runs in line with the national May norm; 0.0% of its May days topped AQI 100 versus 1.3% nationally (below average).
May is part of Durham's spring season (March, April, May); the spring page pools all three months.
Activity-specific thresholds: running, cycling, kids' sports.
Right now in Durham
The latest EPA AirNow observation puts Durham's AQI at 41 (PM2.5). The figures above are multi-year month statistics, not today's reading.
View current Durham air quality →Source: EPA Air Quality System (AQS) pre-generated Daily AQI by CBSA files — daily AQI by CBSA (Durham-Chapel Hill, NC), 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.