Charleston, SC Air Quality in May
Across 2019–2025, Charleston's May air quality had a median AQI of 48 (Good) over 217 monitored days in the Charleston-North Charleston, SC area. 0.0% of May days (0 of 217) reached Unhealthy for Sensitive Groups or worse, and fine particulate matter (PM2.5) set the daily AQI on 68.2% of days. The cleanest May on record here was 2020 (median AQI 42, 0 days above 100) and the worst was 2023 (median 53, 0 days above 100, peak AQI 66).
- Good: 59.0%
- Moderate: 41.0%
- Unhealthy for Sensitive Groups: 0.0%
- Unhealthy or worse: 0.0%
Reduce Indoor Ozone in Charleston
Today's main pollutant in Charleston is ground-level ozone (AQI 31). 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
As an Amazon Associate, we earn from qualifying purchases.
How is the air in Charleston in May?
Good on a typical day: median AQI 48 across 2019–2025, with 0.0% of May days above AQI 100. Fine particulate matter (PM2.5) is the main driver.
- ✓59.0% of May days were Good (AQI 0–50), 41.0% Moderate (51–100).
- ✓0 days of 217 reached AQI 101+; the May peak was 80.
- ✓Best May: 2020; worst May: 2023.
Frequently asked questions
What is the air quality like in Charleston in May?▾
Across 2019–2025, the median daily AQI in Charleston in May was 48 (Good). 59.0% of days were Good, 41.0% 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 Charleston?▾
A typical May day in Charleston sits in the Good range (median AQI 48), 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 Charleston's May air quality problems?▾
Fine particulate matter (PM2.5) set the daily AQI on 68.2% of May days in Charleston. The highest May AQI recorded in 2019–2025 was 80 (Moderate), in 2023.
Charleston May air quality, year by year
Charleston May air quality by year (Charleston-North Charleston, SC, EPA AQS daily AQI)
| Year | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| 2019 | 31 | 44 | 0 | 66 | PM2.5 |
| 2020cleanest | 31 | 42 | 0 | 58 | PM2.5 |
| 2021 | 31 | 49 | 0 | 62 | PM2.5 |
| 2022 | 31 | 49 | 0 | 80 | PM2.5 |
| 2023worst | 31 | 53 | 0 | 66 | PM2.5 |
| 2024 | 31 | 44 | 0 | 67 | O3 |
| 2025 | 31 | 49 | 0 | 77 | PM2.5 |
What May air means in Charleston
A typical May day in Charleston sits in the Good range (median AQI 48), 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 48 is in line with Charleston's whole-year median of 47, 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 Charleston runs above the national May norm; 0.0% of its May days topped AQI 100 versus 1.3% nationally (below average).
May is part of Charleston's spring season (March, April, May); the spring page pools all three months.
Activity-specific thresholds: running, cycling, kids' sports.
Right now in Charleston
The latest EPA AirNow observation puts Charleston's AQI at 31 (O3). The figures above are multi-year month statistics, not today's reading.
View current Charleston air quality →Source: EPA Air Quality System (AQS) pre-generated Daily AQI by CBSA files — daily AQI by CBSA (Charleston-North Charleston, SC), 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.