SmogRank / United States / Connecticut / Hartford
Hartford, month by month
Hartford has a measured daily mean on 1,368 days since 1 January 2023. Its worst month was June 2023, at 66 US AQI (16.9 µg/m³), 337th of 1,603 cities on that month's world ranking. Its cleanest was March 2024, at 21 US AQI (3.8 µg/m³). 2025 averaged 41 US AQI (7.3 µg/m³), against 34 US AQI (6.2 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
Hartford's worst months
| Month | US AQI | World rank | Episode |
|---|---|---|---|
| June 2023 | 6616.9 µg/m³ | 337thof 1,603 | Eastern United States and Canada, June and July 2023 Eastern United States and Canada, May and June 2023 |
| July 2026 | 5712.5 µg/m³ | 811thof 2,784 | Northern United States and Canada, July 2026 |
| July 2023 | 5712.3 µg/m³ | 365thof 1,432 | Eastern United States and Canada, June and July 2023 |
| June 2025 | 5611.7 µg/m³ | 861stof 2,508 | – |
| July 2025 | 5511.0 µg/m³ | 1,051stof 2,889 | North-eastern United States and Canada, 29 July to 9 August 2025 North-eastern United States and Canada, 24 to 28 July 2025 |
| February 2026 | 5410.9 µg/m³ | 1,208thof 2,866 | North-eastern United States and Canada, 14 to 19 February 2026 |
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.
Hartford's worst days
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, Hartford, United States, 1 Jan 2023 – 12 Oct 2026. Monitor data from AirNow, via OpenAQ and from the publisher directly; sources listed at smogrank.com/sources. smogrank.com/us/hartford/history (accessed 13 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.
Hartford now: the last 24 hours, its ranks today and the last 12 months day by day.
Updated 2026-10-13 04:07 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).