Redwood City, 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.
Redwood City, CA air quality summary: Redwood City, CA, has a clean air score of 69.8 and an overall grade of C. The city records a PM2.5 annual mean of 8.3 micrograms per cubic meter. Redwood City records a PM2.5 annual mean of 8.3, representing a moderate but relevant level for long-term particulate exposure. Long-term air quality in Redwood City has remained modest and stable over recent years.
Clean Air Score
A score of 69.8 suggests moderate long-term air quality within the San Francisco Peninsula area. The grade of C reflects annual particulate concentrations that are typical for its urban coastal environment.
🏡 What This Means for Buying
Evaluating air quality is a prudent part of any long-term housing evaluation in Redwood City. Residents are encouraged to view this data alongside other community health and lifestyle factors.
Indoor Air Quality in Redwood City, 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 Redwood City.
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 Redwood City:
- 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.
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🩺 My Health Risk Assessment
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</> Create Free Widget🏡 Property Value Impact Analysis
Between 2019 and 2024, Redwood City's air quality worsened by 0.1 μg/m³. Based on NBER studies, this change correlates with a estimated 0.4% decrease in relative property value retention.
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Why Redwood City earned a 69.8
Raw inputs, scoring weights, and data coverage for this city.
Best Time to Run
Find the cleanest hours for your run today.
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% | 52.8 |
| Unhealthy Days | 25% | 100 |
| 5-Year Trend | 20% | 50 |
| Seasonal Variability | 10% | 87.3 |
| 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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Redwood City Air Quality FAQs
Is Redwood City a good fit for people who care about long-term air quality?
Redwood City offers a moderate air quality profile, holding a score of 69.8 and a grade of C. The annual PM2.5 mean stands at 8.3.
How often does Redwood City experience unhealthy air days?
Redwood City has an unhealthy air day frequency of 0%, which is consistent with its grade of C. This indicates that acute pollution spikes are currently infrequent.
Is air quality in Redwood City improving or getting worse over time?
Air quality in Redwood City is currently classified as neutral, indicating that pollution levels have not seen significant shifts recently.
Does air quality vary across different parts of Redwood City?
Particulate levels in Redwood City can vary due to proximity to major transit corridors and the local industrial base. Local geography and Bay area wind patterns can also influence how pollution disperses across the city.