SmogRank / United States / Ohio / Westerville
Westerville, month by month
Westerville has a measured daily mean on 1,170 days since 11 July 2023. Its worst month was July 2026, at 76 US AQI (22.4 µg/m³), 269th of 2,784 cities on that month's world ranking. Its cleanest was May 2025, at 36 US AQI (6.4 µg/m³). 2025 averaged 52 US AQI (9.5 µg/m³), against 47 US AQI (8.5 µg/m³) in 2024.
Every month since 2023
The US EPA's Air Quality Index for PM2.5 (2024 breakpoints). Show values as: µg/m³ · US AQI · India AQI · China AQI · European AQI · UK DAQI · Canada AQHI+. About the scales
Months without a mean, and why
1 month
| Month | Why |
|---|---|
| Jul 2023 | 21 of 31 days measured; a month needs 22. |
A day counts once 18 hours of it are measured; a month needs 70% of its days.
Westerville's worst months
| Month | US AQI | World rank | Episode |
|---|---|---|---|
| July 2026 | 7622.4 µg/m³ | 269thof 2,784 | Northern United States and Canada, July 2026 North-eastern United States, June and July 2026 |
| June 2025 | 6214.8 µg/m³ | 465thof 2,508 | Northern United States and Canada, June 2025 Northern United States and Canada, May and June 2025 |
| February 2026 | 5913.5 µg/m³ | 885thof 2,866 | North-eastern United States and Canada, 9 to 10 February 2026 |
| August 2023 | 5712.3 µg/m³ | 311thof 1,980 | – |
| July 2025 | 5511.4 µg/m³ | 961stof 2,889 | North-eastern United States and Canada, 29 July to 9 August 2025 North-eastern United States, July 2025 |
| December 2025 | 5511.3 µg/m³ | 1,072ndof 3,006 | – |
Monthly means over the days measured; finished months only. World rank: its place on that month's world ranking of every city with enough days. Each month opens that ranking.
Westerville's worst days
| Day | US AQI | Episode |
|---|---|---|
| 17 Jul 2026 | 277202.0 µg/m³ | Northern United States and Canada, July 2026 |
| 17 Jul 2023 | 15459.2 µg/m³ | United States and Canada, July 2023 |
| 16 Jul 2026 | 12846.3 µg/m³ | Northern United States and Canada, July 2026 |
| 19 Jul 2026 | 11641.6 µg/m³ | Northern United States and Canada, July 2026 |
| 20 Jul 2026 | 10436.8 µg/m³ | Northern United States and Canada, July 2026 |
| 7 Jun 2025 | 9934.6 µg/m³ | Northern United States and Canada, May and June 2025 |
| 8 Jun 2025 | 9633.1 µg/m³ | Northern United States and Canada, May and June 2025 |
| 4 Jun 2025 | 9432.3 µg/m³ | Northern United States and Canada, May and June 2025 |
| 5 Jul 2025 | 9331.8 µg/m³ | North-eastern United States, July 2025 |
| 1 Jul 2026 | 9331.8 µg/m³ | North-eastern United States, June and July 2026 |
Daily means, the highest since 11 Jul 2023; the WHO's daily guideline is 15 µg/m³. Each date opens that day's world ranking, and each episode the bad-air spell it was part of.
Use this history
SmogRank, PM2.5 monthly and daily means, Westerville, United States, 11 Jul 2023 – 11 Oct 2026. Monitor data from AirNow, via OpenAQ and from the publisher directly; sources listed at smogrank.com/sources. smogrank.com/us/westerville/history (accessed 12 Oct 2026).
You're welcome to reuse a single chart, image or figure with this citation and a link. Terms. Raw monitor readings in bulk are published by OpenAQ, under each provider's licence.
Westerville now: the last 24 hours, its ranks today and the last 12 months day by day.
Updated 2026-10-12 21:07 UTC. Values are PM2.5 (fine particles), the median of each city's monitors, as the US AQI PM2.5 sub-index. Some low-cost readings: Sensor.Community, ODbL (data and licence). Some readings: Uzhydromet (Uzbekistan's Hydrometeorological Service); Department of Environment, Nepal; Vietnam's government monitors; Aurassure; Umhverfisstofnun (Environment Agency of Iceland); RMCAB (Secretaría Distrital de Ambiente, Bogotá); Love My Air (City and County of Denver), no reuse terms published (why we use them).