South San Francisco, CA
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.
South San Francisco, CA air quality summary: South San Francisco, CA, has a clean air score of 79.7 and an overall grade of B. The city's annual mean for PM2.5 is 6.6. South San Francisco has an annual PM2.5 mean of 6.6. The long-term air quality in South San Francisco is improving, showing a positive trend over recent years.
Clean Air Score
A clean air score of 79.7 and a grade of B represent favorable long-term air quality in South San Francisco. These metrics suggest that particulate matter levels are generally within ranges considered acceptable for long-term residential exposure.
🏡 What This Means for Buying
Air quality is a relevant consideration for those looking at property in South San Francisco. These long-term averages provide a baseline for understanding the local environmental context.
Indoor Air Quality in South 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 South San Francisco.
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 South 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 South San Francisco Homes:
🩺 My Health Risk Assessment
See how South San Francisco's air quality affects you and your family specifically.
Health Advice
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</> Create Free Widget🏡 Property Value Impact Analysis
Between 2019 and 2024, South 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.
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Why South San Francisco earned a 79.7
Raw inputs, scoring weights, and data coverage for this city.
Best Time to Run
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Cycling Forecast
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📅 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% | 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
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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South San Francisco Air Quality FAQs
Is South San Francisco a good fit for people who care about long-term air quality?
South San Francisco has a clean air score of 79.7 and an overall grade of B. With a PM2.5 annual mean of 6.6, it provides a generally good environment for long-term air quality.
What is the frequency of unhealthy air or long-term pollution exposure in South San Francisco?
South San Francisco has an unhealthy days percentage of 0. This supports the city's B grade and reflects its relatively low PM2.5 annual mean of 6.6.
Is air quality in South San Francisco improving or getting worse over time?
Air quality in South San Francisco is improving. This indicates that the long-term data shows a reduction in particulate levels over the past several years.
Are there specific neighborhoods in South San Francisco with better or worse air quality?
Air quality can vary within the city due to local traffic, industry, and location patterns. While city-wide data is provided, local factors can influence the air quality in specific areas.