Baltimore Air Quality in May
Across 2019–2025, Baltimore's May air quality had a median AQI of 48 (Good) over 217 monitored days in the Baltimore-Columbia-Towson, MD area. 2.8% of May days (6 of 217) reached Unhealthy for Sensitive Groups or worse, and ground-level ozone set the daily AQI on 79.3% of days. The cleanest May on record here was 2025 (median AQI 43, 0 days above 100) and the worst was 2021 (median 46, 3 days above 100, peak AQI 122).
- Good: 62.2%
- Moderate: 35.0%
- Unhealthy for Sensitive Groups: 2.8%
- Unhealthy or worse: 0.0%
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How is the air in Baltimore in May?
Good on a typical day: median AQI 48 across 2019–2025, with 2.8% of May days above AQI 100. Ground-level ozone is the main driver.
- ✓62.2% of May days were Good (AQI 0–50), 35.0% Moderate (51–100).
- ✓6 days of 217 reached AQI 101+; the May peak was 122.
- ✓Best May: 2025; worst May: 2021.
Frequently asked questions
What is the air quality like in Baltimore in May?▾
Across 2019–2025, the median daily AQI in Baltimore in May was 48 (Good). 62.2% of days were Good, 35.0% Moderate, and 2.8% 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 Baltimore?▾
A typical May day in Baltimore sits in the Good range (median AQI 48), so running, cycling and children's outdoor play are fine for everyone on most days; about 1 day in 36 of May days (2.8%) reached AQI 101+ in 2019–2025.
Which pollutant causes Baltimore's May air quality problems?▾
Ground-level ozone set the daily AQI on 79.3% of May days in Baltimore. The highest May AQI recorded in 2019–2025 was 122 (Unhealthy for Sensitive Groups), in 2021.
Baltimore May air quality, year by year
Baltimore May air quality by year (Baltimore-Columbia-Towson, MD, EPA AQS daily AQI)
| Year | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| 2019 | 31 | 53 | 0 | 77 | O3 |
| 2020 | 31 | 44 | 0 | 64 | O3 |
| 2021worst | 31 | 46 | 3 | 122 | O3 |
| 2022 | 31 | 46 | 0 | 97 | O3 |
| 2023 | 31 | 54 | 1 | 101 | O3 |
| 2024 | 31 | 47 | 2 | 115 | O3 |
| 2025cleanest | 31 | 43 | 0 | 90 | O3 |
What May air means in Baltimore
A typical May day in Baltimore sits in the Good range (median AQI 48), so running, cycling and children's outdoor play are fine for everyone on most days; about 1 day in 36 of May days (2.8%) reached AQI 101+ in 2019–2025.
May's median AQI of 48 is in line with Baltimore's whole-year median of 49, 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 Baltimore runs above the national May norm; 2.8% of its May days topped AQI 100 versus 1.3% nationally (above average).
May is part of Baltimore's spring season (March, April, May); the spring page pools all three months.
Activity-specific thresholds: running, cycling, kids' sports.
Right now in Baltimore
The latest EPA AirNow observation puts Baltimore's AQI at 43 (PM2.5). The figures above are multi-year month statistics, not today's reading.
View current Baltimore air quality →Source: EPA Air Quality System (AQS) pre-generated Daily AQI by CBSA files — daily AQI by CBSA (Baltimore-Columbia-Towson, MD), 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.