Palo Alto, 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.
Palo Alto, CA air quality summary: Palo Alto, CA, has a clean air score of 69.8 and an overall grade of C. The annual mean for PM2.5 in the city is 8.3. Palo Alto has an annual PM2.5 mean of 8.3. The long-term air quality trend in Palo Alto is currently neutral, reflecting limited change over recent years.
Clean Air Score
The clean air score of 69.8 and a C grade reflect moderate long-term air quality in Palo Alto. These values indicate that particulate matter levels are relevant for residents to consider when evaluating the long-term environment.
🏡 What This Means for Buying
Prospective residents in Palo Alto should include long-term air quality data as part of their environmental assessment. These metrics provide factual context for understanding the local atmospheric conditions.
Indoor Air Quality in Palo Alto, 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 Palo Alto.
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 Palo Alto:
- 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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Between 2019 and 2024, Palo Alto'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 Palo Alto 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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Palo Alto Air Quality FAQs
Is Palo Alto a good fit for people who care about long-term air quality?
Palo Alto has a clean air score of 69.8 and an overall grade of C. Its PM2.5 annual mean of 8.3 indicates a moderate environment for long-term air quality considerations.
What is the frequency of unhealthy air or long-term pollution exposure in Palo Alto?
Palo Alto has an unhealthy days percentage of 0. This supports its C grade and reflects its annual PM2.5 level of 8.3.
Is air quality in Palo Alto improving or getting worse over time?
Air quality in Palo Alto is neutral. This suggests that long-term particulate levels have remained relatively stable without a significant upward or downward shift.
Are there specific neighborhoods in Palo Alto with better or worse air quality?
Air quality can vary within the city due to local traffic, industry, and location patterns. Local factors like proximity to major transit routes can influence conditions in different areas.