Metro area air quality · 2025

Greenfield Town, MA

Median AQI 38 (Good). 76.9% of monitored days rated Good across this metro's EPA monitoring network.

38
Median AQI
76.9%
Good-air days
0
Unhealthy days
61%
Cleaner than US metros

Greenfield Town, MA posted a 2025 median AQI of 38 (Good) with 76.9% Good days

According to the U.S. EPA Air Quality System, the Greenfield Town, MA CBSA recorded a median AQI of 38 across 364 monitored days in 2025, with 76.9% rated Good and 0 unhealthy or worse. This is an annual metro comparison, not a live advisory.

Data source EPA Air Quality System (AQS)

Cleaner than US metros
The Greenfield Town, MA CBSA's 76.9% Good-day share places it cleaner than 61% of US metros in 2025.
Closest median-AQI peer
Appleton, WI (72.3% Good, median AQI 38) is the closest nationwide median-AQI peer to Greenfield Town, MA.
2020–2025 Good-day shift
Greenfield Town, MA's Good-day share moved +10.2 points from 2020 to 2025 (median AQI -5).
Median AQI
Median AQI: 38

Aggregated from EPA Air Quality System (2025), 364 monitored days. EPA AQS →

The verdict

Greenfield Town, MA's Good-day share (76.9%) sits in the middle CBSA tercile on this extract. On the EPA scale the metro runs good, cleaner than the median US metro, with a median AQI of 38 and 76.9% of 364 monitored days in the Good band.

38
median AQI · Good
76.9%
days rated Good
61%
cleaner than US metros
114
worst single reading

No day crossed into the Unhealthy tier across the metro's monitors in 2025.

Annual release change

What changed in the 2025 EPA annual release

2024 → 2025
  • Greenfield Town, MA metro's Good-day share fell from 81.1% to 77.6% between the 2024 and 2025 EPA annual releases, a change of -3.5 percentage points.
  • Greenfield Town, MA metro's peak single-day AQI rose from 94 to 114 between the 2024 and 2025 EPA annual releases, a change of +20 points.

Compared against 365 monitored days in 2024 and 361 in 2025. These are arithmetic differences between two stored EPA annual summaries, not a cause claim or a live advisory.

National release changes Two-year CSV

Greenfield Town, MA's Good-day share (76.9%) sits in the middle CBSA tercile on this extract. Signature read: 76.9% Good-day share (mid tercile vs CBSA corpus). Aggregated EPA AQS monitors across this Core-Based Statistical Area logged a median Air Quality Index of 38 over 364 measured days in 2025 (Good / Good). The monitored-day split lands at 280 Good (77%), 81 Moderate (22%), and 3 Unhealthy-for-Sensitive-Groups (1%). The 90th-percentile AQI finished at 59; the highest single-day reading hit 114 (USG).

Across 2020–2025, Good-day share shifted +10.2 points and median AQI moved -5 (improving). No Unhealthy-tier days appear in this annual dataset. Metros with comparable AQI profiles include Appleton, WI (72.3% good, AQI 38); Billings, MT (86.3% good, AQI 38); Burlington-South Burlington, VT (87.7% good, AQI 38).

Understanding AQI →

Air Quality Summary

Median AQI

38

Good

Good Days

76.9%

280 of 364 days

Max AQI

114

USG

Health Grade

Good

90th pct: 59

AQI Day Breakdown (2025)

Distribution of 364 monitored days across EPA AQI categories.

Good

280

77%

Moderate

81

22%

USG

3

1%

Unhealthy

0

0%

Very Unhealthy

0

0%

Hazardous

0

0%

Health Impact Assessment

Good

The Greenfield Town, MA metro area's air quality is rated Good based on 76.9% good air days. No unhealthy air days were recorded in 2025.

Air quality is generally acceptable. Unusually sensitive people should monitor real-time conditions at AirNow.gov during high-pollution events.

How does the Greenfield Town, MA metro compare?

How Greenfield Town, MA compares

Good-day share better than typical
Greenfield Town, MA 76.9%
Appleton, WI 72.3%
Typical US metro 70.6%
Median AQI better than typical
Greenfield Town, MA 38
Appleton, WI 38
Typical US metro 41
Unhealthy days / yr better than typical
Greenfield Town, MA 0
Appleton, WI 6
Typical US metro 1

5-Year Air Quality Trend

Air quality is improving in the Greenfield Town, MA metro. Highest Good-day share: 2024 (81.1%, 296 of 365 monitored days).

Year Good Moderate Unhealthy Median AQI
2020 246 119 0 43
2021 228 137 0 44
2022 271 93 0 40
2023 246 113 1 43
2024 296 69 0 36
2025 280 81 0 38

Metros with a similar median AQI

CBSA peers nationwide whose annual median AQI sits near Greenfield Town, MA (38).

Appleton, WI

Median AQI 38 · 72.3% Good-day share

38

Billings, MT

Median AQI 38 · 86.3% Good-day share

38

Burlington-South Burlington, VT

Median AQI 38 · 87.7% Good-day share

38

Charlottesville, VA

Median AQI 38 · 81.0% Good-day share

38

Corning, NY

Median AQI 38 · 83.3% Good-day share

38

Dickinson, ND

Median AQI 38 · 82.7% Good-day share

38

Metros with similar unhealthy-day exposure

A second relationship type: metros whose unhealthy-or-worse day count is closest to Greenfield Town, MA's 0 (independent of median AQI).

Aberdeen, SD

0 unhealthy-or-worse days · median AQI 27

27

Aberdeen, WA

0 unhealthy-or-worse days · median AQI 22

22

Adrian, MI

0 unhealthy-or-worse days · median AQI 41

41

Akron, OH

0 unhealthy-or-worse days · median AQI 45

45

Albany, GA

0 unhealthy-or-worse days · median AQI 46

46

Albany, OR

0 unhealthy-or-worse days · median AQI 27

27

Frequently Asked Questions

How many unhealthy air days does Greenfield Town, MA have? ▼
In 2025, the Greenfield Town, MA metro area recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 114.
What is the air quality in the Greenfield Town, MA metro area? ▼
The Greenfield Town, MA metro area has a median Air Quality Index (AQI) of 38, rated "Good." 76.9% of monitored days (280 out of 364) had good air quality in 2025.
Is air quality in Greenfield Town, MA getting better or worse? ▼
Air quality in the Greenfield Town, MA metro is improving across floor-qualifying years (2020-2025); years with fewer than 100 monitored days are excluded from that direction. Highest qualifying Good-day share: 2024 at 81.1% (296 of 365 days). Lowest qualifying Good-day share: 2021 at 62.5% (228 of 365 days).
What does AQI 38 mean for health? ▼
An AQI of 38 is "Good", air quality is satisfactory and poses little or no health risk. This is the best category on the EPA's AQI scale.
How does Greenfield Town, MA compare to other metro areas? ▼
The Greenfield Town, MA metro has 76.9% good air days. Similar metros: Appleton, WI (72.3% good), Billings, MT (86.3% good), Burlington-South Burlington, VT (87.7% good).
What is the 90th percentile AQI for Greenfield Town, MA? ▼
The 90th percentile AQI for the Greenfield Town, MA metro area is 59, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 114 (USG).

Data Sources

Primary Source: U.S. Environmental Protection Agency (EPA), Air Quality System (AQS), Annual AQI by CBSA dataset for Greenfield Town, MA, 2025. See our methodology for how AQI, median, and coverage figures are computed.

Read our methodology , how this data is sourced, computed, and verified.

Source: U.S. EPA Air Quality System (AQS) Annual AQI by CBSA summary, Greenfield Town, MA · 2020–2025