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Defiance, OH

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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.

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Note: Defiance does not have its own EPA monitor and this page relies on the nearest monitor in Lima, 39.7 miles away.
📍 Homebuyer Guide 📊 Data Coverage: 95.3% 📅 2021-2025 Trends

Defiance, OH air quality summary: Defiance, OH, maintains a clean air score of 83.8 and a grade of B, indicating a very healthy long-term atmosphere for its residents. The city records an annual PM2.5 mean of 5.9 µg/m³, reflecting low levels of particulate exposure. In Defiance, the annual PM2.5 mean is 5.9 µg/m³, representing a relatively low level of long-term particulate exposure. The long-term air quality in Defiance has been improving over recent years.

Clean Air Score

84
Grade B

A grade of B and a score of 83.8 suggest that Defiance experiences high standards of air quality over time. These ratings reflect a consistent environment with minimal pollution impact on the community.

🏡 What This Means for Buying

The B grade for Defiance is an encouraging sign for potential residents. Air quality is a stable and reliable factor that contributes to the overall desirability of the area for long-term health.

Best time for outdoor visits: Check seasonal chart

Indoor Air Quality in Defiance, OH

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 Defiance.

AQI 0-50

Good

Open 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

Moderate

Open 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 Groups

Open 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+

Unhealthy

Open 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 Defiance:

  • 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.

People also search: "indoor air quality in Defiance, OH"

🩺 My Health Risk Assessment

See how Defiance's air quality affects you and your family specifically.

Current Risk Level
Low Risk
🟢
💡

Health Advice

Enjoy the outdoors! Air quality is great.

Est. Annual "Risky Days" for you: ~0 days/year

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🏡 Property Value Impact Analysis

Estimated Impact (5-Year)
Positive Signal
+4.8% theoretical value retention

Between 2019 and 2024, Defiance's air quality improved by 1.2 μg/m³. Based on NBER studies, this change correlates with a estimated 4.8% increase in relative property value retention.

* Methodology: Comparison based on National Bureau of Economic Research (NBER) Working Paper 15655 correlation between PM2.5 reduction and housing prices. This is a theoretical estimate for informational purposes only.
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Annual PM2.5
5.9 μg/m³
WHO Target: <5.0
Good Days
100.0 %
% days AQI < 100
5-Year Trend
Improving
↑ Improving
Long-term direction
Extreme Days
0 days/yr
Days AQI > 150 (Est.)

Why Defiance earned a 83.8

Raw inputs, scoring weights, and data coverage for this city.

See full formula
Annual Air Quality
5.9 μg/m³
Component score 86.5 × 40% = 34.6 points
Unhealthy Days
0 days/yr est.
0% of days above AQI 100. Component score 100 × 25% = 25.0 points
5-Year Trend
Improving
Component score 56 × 20% = 11.2 points
Seasonal Variability
91.8
Higher means steadier month-to-month air. Weighted contribution: 9.2 points
Extreme Events
100
Captures severe pollution spikes. Weighted contribution: 5.0 points
Coverage & Monitoring
95.3%
Proxy monitor: Lima (39.7 miles away)

📅 Past 30 Days Trend

Real-time daily PM2.5 AQI

Live Data

Score Breakdown

Component Weight Score Contribution
Annual Air Quality 40% 86.5
Unhealthy Days 25% 100
5-Year Trend 20% 56
Seasonal Variability 10% 91.8
Extreme Events 5% 100

Explore More Air Quality Data

Frequently Asked Questions

How often is this air quality data updated? Our historical trend models and annual rankings are updated regularly based on official EPA data to ensure reports reflect the latest available long-term trends.
What sources does CleanAirData use? We rely strictly on official U.S. Environmental Protection Agency (EPA) monitoring station data for all historical air quality scoring and reports.
Data sourced from U.S. Environmental Protection Agency (EPA) — See our methodology

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.

Data provided for informational purposes only. Always consult local health officials during extreme smoke or pollution events.

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Defiance Air Quality FAQs

Is Defiance a good fit for people who care about long-term air quality?

Defiance is an excellent choice for those prioritizing air quality, with its clean air score of 83.8 and grade of B. The annual PM2.5 mean of 5.9 µg/m³ indicates a very clean long-term atmosphere.

What is the frequency of unhealthy air or long-term pollution exposure in Defiance?

Defiance reports an unhealthy days percentage of 0, which is an excellent result for its grade. This means that residents are almost never exposed to high levels of pollution.

Is air quality in Defiance improving or getting worse over time?

The air quality trend in Defiance is currently improving, providing further confidence for the city's future environmental health.

Does air quality vary across different parts of Defiance?

Air quality can vary within Defiance due to local traffic, industry, and location patterns, although the city-wide grade remains a strong general indicator.