SmogRank / United States / Massachusetts / Greenfield
Greenfield, month by month
Greenfield has a measured daily mean on 1,331 days since 1 January 2023. Its worst month was July 2023, at 58 US AQI (12.8 µg/m³), 306th of 1,432 cities on that month's world ranking. Its cleanest was April 2024, at 21 US AQI (3.8 µg/m³). 2025 averaged 38 US AQI (6.8 µg/m³), against 32 US AQI (5.7 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 |
|---|---|
| Aug 2024 | 12 of 31 days measured; a month needs 22. The others: 19 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.
Greenfield's worst months
| Month | US AQI | World rank | Episode |
|---|---|---|---|
| July 2023 | 5812.8 µg/m³ | 306thof 1,432 | United States and Canada, July 2023 Eastern United States and Canada, June and July 2023 |
| June 2023 | 5712.4 µg/m³ | 522ndof 1,603 | Eastern United States and Canada, June and July 2023 Eastern United States and Canada, May and June 2023 |
| July 2026 | 5410.8 µg/m³ | 1,165thof 2,784 | Northern United States and Canada, July 2026 |
| June 2025 | 5310.3 µg/m³ | 1,216thof 2,508 | Northern United States and Canada, May and June 2025 |
| December 2023 | 529.8 µg/m³ | 750thof 2,247 | – |
| 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.
Greenfield'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, Greenfield, United States, 1 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/greenfield-massachusetts/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.
Greenfield now: the last 24 hours, its ranks today and the last 12 months day by day.
Updated 2026-10-13 02:07 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).