SmogRank / United States / Connecticut / Waterbury
Waterbury, month by month
Waterbury has a measured daily mean on 1,292 days since 11 January 2023. Its worst month was June 2023, at 68 US AQI (18.0 µg/m³), 304th of 1,603 cities on that month's world ranking. Its cleanest was March 2024, at 22 US AQI (3.9 µg/m³). 2025 averaged 37 US AQI (6.7 µg/m³), against 34 US AQI (6.1 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
3 months
| Month | Why |
|---|---|
| Apr 2023 | 3 of 30 days measured; a month needs 21. The others: 27 with under 18 hours of readings or readings that failed our checks. |
| Mar 2023 | 20 of 31 days measured; a month needs 22. The others: 11 with under 18 hours of readings or readings that failed our checks. |
| Jan 2023 | 7 of 31 days measured; a month needs 22. The others: 14 with under 18 hours of readings or readings that failed our checks. |
A day counts once 18 hours of it are measured; a month needs 70% of its days.
Waterbury's worst months
| Month | US AQI | World rank | Episode |
|---|---|---|---|
| June 2023 | 6818.0 µg/m³ | 304thof 1,603 | Eastern United States and Canada, June and July 2023 Eastern United States and Canada, May and June 2023 |
| July 2026 | 5812.8 µg/m³ | 756thof 2,784 | Northern United States and Canada, July 2026 |
| July 2023 | 5712.2 µg/m³ | 375thof 1,432 | Eastern United States and Canada, June and July 2023 |
| June 2025 | 5310.0 µg/m³ | 1,296thof 2,508 | – |
| February 2026 | 529.9 µg/m³ | 1,418thof 2,866 | North-eastern United States and Canada, 14 to 19 February 2026 |
| August 2025 | 529.5 µg/m³ | 1,350thof 2,901 | North-eastern United States and Canada, 29 July to 9 August 2025 |
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.
Waterbury's worst days
| Day | US AQI | Episode |
|---|---|---|
| 7 Jun 2023 | 18096.5 µg/m³ | Eastern United States and Canada, May and June 2023 |
| 8 Jun 2023 | 16575.4 µg/m³ | Eastern United States and Canada, May and June 2023 |
| 16 Jul 2026 | 15662.2 µg/m³ | Northern United States and Canada, July 2026 |
| 6 Jun 2023 | 15358.2 µg/m³ | Eastern United States and Canada, May and June 2023 |
| 1 Jul 2023 | 14352.7 µg/m³ | Eastern United States and Canada, June and July 2023 |
| 30 Jun 2023 | 13247.9 µg/m³ | Eastern United States and Canada, June and July 2023 |
| 18 Jul 2026 | 12043.2 µg/m³ | Northern United States and Canada, July 2026 |
| 26 Jul 2025 | 10938.7 µg/m³ | North-eastern United States and Canada, 24 to 28 July 2025 |
| 5 Aug 2025 | 10838.5 µg/m³ | North-eastern United States and Canada, 29 July to 9 August 2025 |
| 17 Jul 2026 | 9532.8 µg/m³ | Northern United States and Canada, July 2026 |
Daily means, the highest since 11 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, Waterbury, United States, 11 Jan 2023 – 11 Oct 2026. Monitor data from AirNow, via OpenAQ and from the publisher directly; sources listed at smogrank.com/sources. smogrank.com/us/waterbury/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.
Waterbury now: the last 24 hours, its ranks today and the last 12 months day by day.
Updated 2026-10-13 01:07 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).