What Is the Air Quality in Cheshire, New Hampshire?
Cheshire, New Hampshire has an Air Quality Grade of B (good) with a 5-year median AQI of 38. The dominant pollutant is Fine Particulate Matter (PM2.5), and air quality has been improving over the past decade.
Cheshire, New Hampshire Air Quality Snapshot
| Air Quality Grade | B69/100 |
| 5-Year Median AQI | 38 (Good) |
| Most Recent Median AQI (2023) | 41 (Good) |
| Dominant Pollutant | Fine Particulate Matter (PM2.5) |
| 10-Year Trend | Improving (-0.43 AQI/yr) |
| Unhealthy Days (last 5 yr) | 3 |
| National Rank (cleanest = #1) | #372 of 1,020 (36th cleanest percentile) |
| New Hampshire Rank | #5 of 7 |
What Does the B Grade Mean?
Cheshire, New Hampshire earns a B — air quality is reliably in the safe range for most residents most of the time, with a 5-year median AQI of 38. Sensitive groups will see occasional caution days, but the typical resident will not need to change behavior based on air quality.
Cheshire, New Hampshire's 5-year median AQI of 38 is 3 points below the national average of 41 — meaningfully cleaner than the typical U.S. metro tracked here. Within New Hampshire, Cheshire, New Hampshire's air quality is roughly typical for the state, where the average city posts a 5-year median AQI of 38.
For context within New Hampshire: Rockingham, New Hampshire currently holds the state's cleanest grade (B, AQI 40), while Merrimack, New Hampshire sits at the bottom (C, AQI 37).
What's in Cheshire, New Hampshire's Air?
The dominant pollutant in Cheshire, New Hampshire is Fine Particulate Matter (PM2.5). Fine particulate matter — particles less than 2.5 micrometers across — comes mostly from combustion: vehicle exhaust, wildfire smoke, residential wood burning, and industrial emissions. Because these particles are small enough to enter the bloodstream, PM2.5 is the pollutant most strongly linked to cardiovascular disease, respiratory illness, and premature death.
Days by Dominant Pollutant (2023)
| Pollutant | Days as Dominant | Share of Year |
|---|---|---|
| Fine Particulate Matter (PM2.5) | 214 | 59% |
| Ground-Level Ozone | 149 | 41% |
Is the Air Getting Better or Worse?
Air quality in Cheshire, New Hampshire has been improving over the past decade, with median AQI dropping by roughly 0.4 points per year. That is consistent with the broader national pattern — most U.S. metros have seen steady reductions in particulate and ozone pollution since the 2010s as cleaner vehicles and power plants come online.
In 2014, Cheshire, New Hampshire posted a median AQI of 45. By 2023 that figure was 41 — a drop of 4 AQI points cleaner across 10 years of EPA records.
Year-by-Year AQI in Cheshire, New Hampshire
| Year | Median AQI | Good Days | Unhealthy Days | Dominant Pollutant |
|---|---|---|---|---|
| 2014 | 45 | 207 | 1 | PM2.5 |
| 2015 | 44 | 224 | 1 | PM2.5 |
| 2016 | 37 | 290 | 1 | Ozone |
| 2017 | 37 | 298 | 0 | Ozone |
| 2018 | 36 | 300 | 0 | Ozone |
| 2019 | 35 | 331 | 0 | Ozone |
| 2020 | 37 | 299 | 0 | PM2.5 |
| 2021 | 40 | 263 | 1 | PM2.5 |
| 2022 | 37 | 304 | 0 | Ozone |
| 2023 | 41 | 253 | 2 | PM2.5 |
Health Context for Cheshire, New Hampshire
Across the past five years, this area has logged just 3 days where AQI rose into the "Unhealthy for Sensitive Groups" range or worse — about 1 days per year, or roughly one every other month. That is a low count by national standards.
For most healthy adults, current air quality in this area does not require any change in behavior. People with severe asthma, COPD, or recent cardiac events should still keep an eye on daily AQI alerts, especially during wildfire season. Because PM2.5 penetrates deep into the lungs and bloodstream, an N95 or KN95 mask provides meaningful protection on smoky or high-particulate days — surgical masks do not.
How This Grade Is Calculated
The AirHistory Air Quality Grade combines four signals: the 5-year median AQI (40% of the score), the 10-year trend direction (30%), the count of unhealthy days per year (20%), and the dominant pollutant type (10%). All four come directly from the EPA Air Quality System (AQS), which aggregates readings from federally certified monitors. Read the full methodology.
Cheshire, New Hampshire has an Air Quality Grade of B (good) with a 5-year median AQI of 38. The dominant pollutant is Fine Particulate Matter (PM2.5), and air quality has been improving over the past decade.
This answer pulls from the EPA Air Quality System (AQS), the authoritative federal source for U.S. air quality and pollution monitoring. The headline number above is the direct answer; what follows is the additional context most readers need to use the answer for a real decision rather than just a fact lookup.
A practical caveat: the headline answer above reflects the most recent the EPA Air Quality System (AQS) vintage; underlying data is often revised for months after first publication, and the right reference for any specific decision is whichever vintage is current at the time of the decision. The as-of date is stamped on every page.
Source: EPA Outdoor Air Quality Data, 2026.