SmogRank / United States / Missouri / Lemay
Lemay, month by month
Lemay has a measured daily mean on 1,338 days since 1 January 2023. Its worst month was June 2023, at 61 US AQI (14.4 µg/m³), 411th of 1,603 cities on that month's world ranking. Its cleanest was August 2025, at 26 US AQI (4.6 µg/m³). 2025 averaged 40 US AQI (7.2 µg/m³), against 38 US AQI (6.9 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 |
|---|---|
| Oct 2026 | 5 of 11 days measured; a month needs 8. The others: 5 with no readings from the monitor, 1 with readings for part of the day (a day needs 18 hours). |
A day counts once 18 hours of it are measured; a month needs 70% of its days.
Lemay's worst months
| Month | US AQI | World rank | Episode |
|---|---|---|---|
| June 2023 | 6114.4 µg/m³ | 411thof 1,603 | Eastern United States and Canada, June and July 2023 |
| June 2025 | 5310.3 µg/m³ | 1,216thof 2,508 | – |
| July 2026 | 5310.0 µg/m³ | 1,357thof 2,784 | Northern United States and Canada, July 2026 |
| February 2026 | 529.6 µg/m³ | 1,508thof 2,866 | – |
| February 2024 | 529.5 µg/m³ | 744thof 2,486 | – |
| May 2023 | 498.9 µg/m³ | 683rdof 1,600 | – |
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.
Lemay's worst days
| Day | US AQI | Episode |
|---|---|---|
| 15 Mar 2025 | 15866.0 µg/m³ | Eastern United States, March 2025 |
| 28 Jun 2023 | 15561.7 µg/m³ | Eastern United States and Canada, June and July 2023 |
| 20 Jul 2026 | 9331.7 µg/m³ | Northern United States and Canada, July 2026 |
| 2 Feb 2024 | 7924.1 µg/m³ | – |
| 16 Jul 2023 | 7924.0 µg/m³ | – |
| 1 Aug 2025 | 7923.9 µg/m³ | – |
| 7 Jun 2023 | 7622.7 µg/m³ | – |
| 4 Oct 2023 | 7521.9 µg/m³ | – |
| 7 Jun 2025 | 7421.7 µg/m³ | – |
| 30 Jun 2026 | 7421.7 µg/m³ | – |
Daily means, the highest since 1 Jan 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, Lemay, United States, 1 Jan 2023 – 5 Oct 2026. Monitor data from AirNow, via OpenAQ and from the publisher directly; sources listed at smogrank.com/sources. smogrank.com/us/lemay/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.
Lemay now: the last 24 hours, its ranks today and the last 12 months day by day.
Updated 2026-10-12 18:07 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).