Mercer, New Jersey Air Quality
Mercer County, New Jersey (NJ)
→ Stableover 10 years
How Mercer, New Jersey Air Quality Compares
Mercer, New Jersey's median AQI of 49is 20% worse than the national average of 41. The area averages 5 unhealthy air days per year. The primary pollutant of concern is Fine Particulate Matter (PM2.5).
Mercer, New Jersey Air Quality: The Full Picture
Mercer, New Jersey (Mercer County) holds an AirHistory Air Quality Grade of C (fair, scoring 61 out of 100), built from 10 years of EPA Air Quality System monitoring. Its median AQI fell 2 points between 2014 (51) and 2023 (49), and the five-year median now sits at 46 — inside the "Good" band on the EPA scale.
The pollutant driving most of the area's AQI readings is Fine Particulate Matter (PM2.5). In 2023, it set the daily AQI on 242 of 365 monitored days (66% of the year), making it the controlling pollutant for the C grade. The single worst reading logged that year hit an AQI of 244 (Very Unhealthy), while the 90th-percentile day — the level the dirtiest 10% of days reach — came in at 70.
In 2023, Mercer County recorded 194 "Good" air days (53% of the 365 days with valid AQI data), 160 "Moderate" days, and 11 days at "Unhealthy for Sensitive Groups" or above. Over the most recent five years on record, monitors logged 26 days that crossed into "Unhealthy for Sensitive Groups" or worse — about 5 per year.
The decade-long trend is essentially flat, with year-to-year median AQI shifting by less than 0.17 points per year on average. The cleanest year in the record was 2020 (median AQI 42), and the most polluted was 2014 (median AQI 51). Because the data come straight from federally certified EPA monitors, these figures track the New Jersey county the monitors physically sit in rather than a city boundary.
Get Mercer, New Jersey's next air-quality update
Subscribe for Mercer, New Jersey air-quality updates by email. No spam, unsubscribe anytime.
10-Year AQI Trend
The solid line shows the median AQI each year. The dashed line shows the 90th percentile (worst 10% of days).
Air Quality Day Breakdown
Number of days per year in each EPA AQI category. Green = Good (AQI 0-50), Yellow = Moderate (51-100), Orange = Unhealthy for Sensitive Groups (101-150), Red = Unhealthy or worse (151+).
Year-by-Year Data
| Year | Median AQI | 90th Pct | Max AQI | Good Days | Moderate | Unhealthy+ | Pollutant |
|---|---|---|---|---|---|---|---|
| 2023 | 49 | 70 | 244 | 194 | 160 | 11 | PM2.5 |
| 2022 | 46 | 61 | 119 | 227 | 135 | 3 | PM2.5 |
| 2021 | 48 | 67 | 130 | 193 | 165 | 7 | PM2.5 |
| 2020 | 42 | 58 | 112 | 262 | 101 | 3 | PM2.5 |
| 2019 | 45 | 64 | 136 | 232 | 131 | 2 | Ozone |
| 2018 | 43 | 67 | 187 | 229 | 129 | 7 | PM2.5 |
| 2017 | 46 | 64 | 133 | 225 | 136 | 4 | PM2.5 |
| 2016 | 48 | 67 | 151 | 198 | 155 | 13 | PM2.5 |
| 2015 | 46 | 77 | 147 | 210 | 145 | 10 | Ozone |
| 2014 | 51 | 71 | 119 | 179 | 180 | 6 | PM2.5 |
What This Means for Mercer County Residents
Mercer, New Jersey has received an Air Quality Grade of C (61/100) based on a decade of monitoring data from the EPA's air quality monitoring program. The current median AQI of 49 falls in the "Good" range.
The primary pollutant affecting this area is Fine Particulate Matter (PM2.5). Over the past 5 years, this area has averaged 5 unhealthy air quality days per year, days when sensitive groups (children, elderly, those with respiratory conditions) should limit outdoor activity. The American Lung Association's State of the Air report provides additional context on long-term health risks from air pollution exposure.
Related Cities in New Jersey
AQI: 38 · Grade: B
AQI: 48 · Grade: C
AQI: 50 · Grade: C
AQI: 43 · Grade: C
AQI: 44 · Grade: C
AQI: 43 · Grade: B
AQI: 44 · Grade: B
AQI: 44 · Grade: C
Frequently Asked Questions
Mercer, New Jersey has a current median AQI of 49, which falls in the "Good" range. The area has received an Air Quality Grade of C (61/100) based on 10 years of EPA monitoring data.
Air quality in Mercer, New Jersey is stable over the past decade. The median AQI has changed by -2 points from 2014 to 2023.
Mercer, New Jersey averages 5 unhealthy air quality days per year over the past 5 years. On these days, sensitive groups including children, the elderly, and those with respiratory conditions should limit outdoor activity.
The primary pollutant affecting Mercer, New Jersey is Fine Particulate Matter (PM2.5). This is the dominant contributor to elevated AQI readings in the Mercer County area.
Mercer, New Jersey averages 5 unhealthy air days per year. This is relatively low, making it a reasonable choice for asthma sufferers. The primary pollutant is Fine Particulate Matter (PM2.5), which is a known asthma trigger.
With a median AQI of 49 (Good), outdoor exercise in Mercer, New Jersey is generally safe year-round. Mercer, New Jersey averages 5 days per year when athletes should move workouts indoors.