Norristown, PA
Long-term air quality
What this page tells you
This page combines annual PM2.5, unhealthy days, 5-year trend, and data coverage so you can compare long-term air quality, not just today's reading.
Norristown, PA air quality summary: Norristown, PA, has a CleanAirData score of 78.2 and a grade of B. Its recorded annual PM2.5 mean is 6.9 µg/m³. Norristown recorded a PM2.5 annual mean of 6.9 µg/m³, which is considered moderate for long-term exposure. The long-term air quality in Norristown has been improving over recent years.
Clean Air Score
The score of 78.2 and grade of B signify that Norristown generally experiences favorable long-term air quality. Particulate levels are typically within acceptable limits for residential areas.
🏡 What This Means for Buying
Air quality should be treated as one factor in a broader relocation or housing decision in Norristown. The environment is characterized by an improving long-term trend.
Indoor Air Quality in Norristown, PA
Outdoor pollution can still affect indoor air when windows are open, filtration is weak, or wildfire smoke moves in.
How to react when today's AQI changes
Use the AQI bands below to decide whether to open windows, run an air purifier, or stay indoors when pollution spikes in Norristown.
AQI 0-50
GoodOpen windows: Open windows if you want fresh air.
Air purifier: No purifier needed for most homes.
Indoor activity: Normal indoor activity is fine.
AQI 51-100
ModerateOpen windows: Sensitive groups should limit open-window time.
Air purifier: Use fans or filtration if dust or pollen is bothering you.
Indoor activity: Most people can stay active indoors.
AQI 101-150
Unhealthy for Sensitive GroupsOpen windows: Keep windows closed.
Air purifier: Run a HEPA purifier in the main room and bedroom.
Indoor activity: Sensitive groups should reduce outdoor exposure.
AQI 151+
UnhealthyOpen windows: Keep windows and doors closed.
Air purifier: Run HEPA continuously and seal obvious drafts.
Indoor activity: Stay indoors as much as possible; use an N95 if you must go out.
Common indoor air concerns in Norristown:
- Seasonal pollen and dust mite allergens
- VOCs from household products
Recommended action: If today's AQI reaches 101 or higher, close windows and run HEPA filtration before indoor air starts to feel smoky or stale.
Top Products for Norristown Homes:
🩺 My Health Risk Assessment
See how Norristown's air quality affects you and your family specifically.
Health Advice
Enjoy the outdoors! Air quality is great.
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</> Create Free Widget🏡 Property Value Impact Analysis
Between 2019 and 2024, Norristown's air quality improved by 0.7 μg/m³. Based on NBER studies, this change correlates with a estimated 2.8% increase in relative property value retention.
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Why Norristown earned a 78.2
Raw inputs, scoring weights, and data coverage for this city.
Best Time to Run
Find the cleanest hours for your run today.
Cycling Forecast
Avoid pollution spikes on your next ride.
📅 Past 30 Days Trend
Real-time daily PM2.5 AQI
🌸 Pollen Outlook
Current Seasonal Forecast
How it worksBased on current seasonal forecast data. Not a long-term pollution rating or relocation score.
Score Breakdown
| Component | Weight | Score Contribution |
|---|---|---|
| Annual Air Quality | 40% | 72.3 |
| Unhealthy Days | 25% | 100 |
| 5-Year Trend | 20% | 53.5 |
| Seasonal Variability | 10% | 93.3 |
| Extreme Events | 5% | 100 |
Explore More Air Quality Data
Frequently Asked Questions
About This Data
Data Sources
Historical air quality mapping and scoring are based completely on official U.S. Environmental Protection Agency (EPA) AirNow API data. 5-day AQI forecasts are provided by WAQI.
Methodology
Our Clean Air Score (0-100) is a proprietary algorithm that weighs multiple factors:
- Annual PM2.5 averages (40%)
- Frequency of unhealthy days (25%)
- 5-year pollution trends (20%)
- Seasonal variability and extreme events (15%)
Updates & Accuracy
Real-time data is updated hourly. Historical aggregate scores are recalculated monthly to reflect the latest trends. While we strive for accuracy, sensor maintenance and local conditions can affect individual readings.
Practical Advice
When AQI > 100: Sensitive groups (children, elderly, asthmatics) should limit prolonged outdoor exertion.
When AQI > 150: Everyone should avoid outdoor exercise and keep windows closed.
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Norristown Air Quality FAQs
Is Norristown a good fit for people who care about long-term air quality?
Norristown, PA, is a solid option for air quality-conscious residents, featuring a score of 78.2 and a grade of B. The annual PM2.5 mean of 6.9 µg/m³ indicates relatively low exposure risk.
How frequent is unhealthy air or long-term pollution exposure in Norristown?
Norristown reports 0% unhealthy days, which aligns with its grade of B and PM2.5 mean of 6.9 µg/m³. This indicates that residents rarely face acute particulate spikes.
Is air quality in Norristown improving or getting worse over time?
Air quality in Norristown has been improving over recent years. This long-term trend suggests a positive trajectory for the local environment.
Does air quality vary across different neighborhoods in Norristown?
Air quality can vary within Norristown at the neighborhood or ZIP-level. Localized factors like traffic and proximity to industry can influence conditions in specific districts.