San Francisco, CA

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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.

Jump to indoor air guidance Read the formula

📍 Homebuyer Guide 📊 Data Coverage: 96.2% 📅 2021-2025 Trends

San Francisco, CA air quality summary: San Francisco, CA has a Clean Air Score of 79.7 and a grade of B, with historical data showing a stronger recent trend. San Francisco records an annual mean PM2.5 concentration of 6.6 µg/m³, which supports a relatively solid long-term air quality profile. The long-term air quality trend in San Francisco is improving, based on the available historical record.

Clean Air Score

Grade B

A B grade means San Francisco's long-term particulate levels are generally controlled, though not at the very top end of the scale.

🏡 What This Means for Buying

For buyers and renters who care about long-term environmental conditions, this B grade is a useful data point when comparing San Francisco housing options.

Best time for outdoor visits: Check seasonal chart

Indoor Air Quality in San Francisco, CA

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 San Francisco.

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 San Francisco:

Wildfire smoke infiltration (PM2.5)
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 San Francisco Homes:

Best HEPA Air Purifier for San Francisco Wildfire Smoke PM2.5 Indoor Air Quality Monitor Formaldehyde & VOC Detector

People also search: "indoor air quality in San Francisco, CA"

🩺 My Health Risk Assessment

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

Current Risk Level

Low Risk

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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

+4.0% theoretical value retention

Between 2019 and 2024, San Francisco's air quality improved by 1 μg/m³. Based on NBER studies, this change correlates with a estimated 4% increase in relative property value retention.

Cleaner Alternatives in CA

* 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.

🏆 Best Neighborhoods in San Francisco

We analyzed air quality across multiple zip codes to find the healthiest spots to live. See which neighborhoods ranked #1.

View Rankings →

Annual PM2.5

6.6 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 San Francisco earned a 79.7

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

See full formula

Annual Air Quality

6.6 μg/m³

Component score 76.6 × 40% = 30.6 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 55 × 20% = 11.0 points

Seasonal Variability

90.8

Higher means steadier month-to-month air. Weighted contribution: 9.1 points

Extreme Events

100

Captures severe pollution spikes. Weighted contribution: 5.0 points

Coverage & Monitoring

96.2%

Direct EPA city monitor

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Best Time to Run

Find the cleanest hours for your run today.

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Cycling Forecast

Avoid pollution spikes on your next ride.

📅 Past 30 Days Trend

Real-time daily PM2.5 AQI

Live Data

Score Breakdown

Component	Weight	Score Contribution
Annual Air Quality	40%	76.6
Unhealthy Days	25%	100
5-Year Trend	20%	55
Seasonal Variability	10%	90.8
Extreme Events	5%	100

Explore More Air Quality Data

View more cities in CA See how San Francisco compares nationally

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.