New Castle, Indiana Air Quality
New Castle has a median AQI of 38, earning an air quality grade of A — excellent air quality that ranks better than 70% of US cities. Air quality has remained relatively stable over the past decade. Particulate matter (PM2.5) is the primary concern, often linked to vehicle traffic, industrial activity, and wildfire smoke. In 2025, New Castle recorded 174 good air quality days (69% of monitored days).
Population: 17,367 • County: Henry
Current AQI
Quick Facts
| Current AQI | 21 — Good |
| Air Quality Grade | A |
| Median AQI (2025) | 38 |
| vs. U.S. Cities | Better than 70% |
| Primary Pollutant | PM2.5 |
| Unhealthy Days/Year | 0 |
| 10-Year Trend | → Stable |
| Data Source | EPA AQS (historical) · AirNow (live) |
Health Recommendation
Air quality is satisfactory, and air pollution poses little or no risk.
It's a great day to be active outside!
5-Day AQI Forecast
Last 90 Days
Current Pollutant Levels
Real-time data from EPA AirNow
Local Air Quality Context
Air quality data for New Castle is sourced from the Mechanicsburg monitoring area, located approximately 10 miles from city center. This EPA-certified station continuously tracks particulate matter (PM2.5), the primary driver of air quality alerts in this area.
New Castle tends to see elevated PM2.5 readings during fall and winter months when temperature inversions trap pollutants near the surface. Wood burning, vehicle exhaust, and reduced wind speeds compound the effect. Residents with respiratory conditions should monitor forecasts closely between November and February.
AQI Trend (10 Years)
Air Quality Days by Year
New Castle Median AQI by Year
Annual EPA air quality data for New Castle — median AQI, day-category breakdown, and primary pollutant per year.
| Year | Median AQI | Good Days | Unhealthy Days | Max AQI | Primary Pollutant |
|---|---|---|---|---|---|
| 2025 | 38 | 174 | — | 95 | PM2.5 |
| 2024 | 34 | 282 | — | 75 | PM2.5 |
| 2023 | 44 | 214 | 10 | 192 | PM2.5 |
| 2022 | 34 | 87 | — | 95 | PM2.5 |
| 2021 | 38 | 78 | — | 82 | PM2.5 |
| 2020 | 39 | 87 | — | 67 | PM2.5 |
| 2019 | 37 | 81 | — | 67 | PM2.5 |
| 2018 | 41 | 80 | 1 | 111 | PM2.5 |
| 2017 | 38 | 86 | — | 66 | PM2.5 |
| 2016 | 37 | 87 | — | 69 | PM2.5 |
Source: EPA Air Quality System (AQS) annual summaries. "Unhealthy Days" includes Unhealthy for Sensitive Groups, Unhealthy, Very Unhealthy, and Hazardous categories.
2025 Air Quality Summary
Primary Pollutant Days (2025)
Days when each pollutant was the primary driver of AQI. Learn about pollutants →
Frequently Asked Questions About New Castle Air Quality
What is the air quality in New Castle today?
The current AQI in New Castle is 21, rated "Good". Air quality is good — outdoor activity is safe for everyone today. Air quality is satisfactory, and air pollution poses little or no risk.
Is air quality in New Castle getting better or worse?
Air quality in New Castle has been stable. The median AQI has risen 1 points (from 37 in 2016 to 38 in 2025).
What is the most common air pollutant in New Castle?
PM2.5 is the primary air pollutant in New Castle, responsible for 253 days (100% of monitored days) in 2025. Particulate matter originates from vehicle exhaust, wildfires, construction, and industrial activity.
How many unhealthy air days does New Castle have per year?
In 2025, New Castle recorded 69% good air quality days (174 days) out of 253 monitored days. There were 0 Unhealthy for Sensitive Groups days and 0 Unhealthy days (AQI above 100). The highest single-day AQI recorded was 95.
What air quality grade does New Castle receive?
New Castle receives an air quality grade of A, placing it better than 70% of US cities. This is based on a median AQI of 38 in 2025, with 174 good air quality days. The EPA monitors air quality in this area continuously using certified monitoring stations.
Air Quality Grade
Better than 70% of US cities
Nearby Cities
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National Rankings
See how New Castle compares to every other US city by air quality.
Best Air Quality Cities →All city rankingsRecommended Air Purifiers for New Castle
New Castle sees its worst PM2.5 during winter temperature inversions when particulates get trapped near ground level. A unit with True HEPA and an auto-mode sensor is most effective for responding to these spikes.
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