New Castle, Delaware Air Quality
New Castle County, Delaware (DE)
↓ Improvingover 10 years
10-Year AQI Trend
The solid line shows the median AQI each year. The dashed line shows the 90th percentile (worst 10% of days). This area has seen measurable air quality improvement over the decade.
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 | 51 | 73 | 282 | 173 | 184 | 8 | PM2.5 |
| 2022 | 48 | 63 | 93 | 208 | 157 | 0 | PM2.5 |
| 2021 | 48 | 67 | 144 | 195 | 166 | 4 | PM2.5 |
| 2020 | 46 | 63 | 105 | 231 | 133 | 2 | PM2.5 |
| 2019 | 47 | 71 | 136 | 207 | 155 | 3 | PM2.5 |
| 2018 | 48 | 71 | 150 | 212 | 147 | 6 | PM2.5 |
| 2017 | 50 | 71 | 147 | 187 | 168 | 10 | PM2.5 |
| 2016 | 52 | 74 | 154 | 173 | 183 | 10 | PM2.5 |
| 2015 | 52 | 84 | 172 | 170 | 185 | 10 | PM2.5 |
| 2014 | 54 | 80 | 153 | 140 | 214 | 11 | PM2.5 |
What This Means for New Castle County Residents
New Castle, Delaware has received an Air Quality Grade of C (64/100) based on a decade of monitoring data from the EPA's air quality monitoring program. The current median AQI of 51 falls in the "Moderate" range.
Encouragingly, air quality here has been improving, with the median AQI dropping by 3 points over the monitoring period. This trend suggests continued investment in emission controls and cleaner energy.
The primary pollutant affecting this area is Fine Particulate Matter (PM2.5). Over the past 5 years, this area has averaged 3 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.
Frequently Asked Questions
New Castle, Delaware has a current median AQI of 51, which falls in the "Moderate" range. The area has received an Air Quality Grade of C (64/100) based on 10 years of EPA monitoring data.
Air quality in New Castle, Delaware is improving over the past decade. The median AQI has changed by -3 points from 2014 to 2023.
New Castle, Delaware averages 3 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 New Castle, Delaware is Fine Particulate Matter (PM2.5). This is the dominant contributor to elevated AQI readings in the New Castle County area.
New Castle, Delaware averages 3 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 51 (Moderate), outdoor exercise in New Castle, Delaware is safe most days, though sensitive individuals should check daily AQI before intense workouts. New Castle, Delaware averages 3 days per year when athletes should move workouts indoors.