City report · California, United States
San Jose Air quality today
Air quality in San Jose currently reads AQI 55 (Moderate): Unusually sensitive people should consider limiting long outdoor exertion.
Air quality right now
AQI 55
Moderate
- PM2.5, fine particles (µg/m³)
- 11.0
- tree cover
- 17.1%
- trees in this area
- 53.7K
- more trees needed
- 40.5K
Measured across a 1.2 mi (2 km) radius around Ballbach and SOFA, San Jose, CA, USA (4.9 sq mi), from a satellite image of Sep 12, 2026. Lower AQI is better: 0–50 is Good, above 300 is Hazardous.
San Jose · AQI 55 (Moderate)
San Jose's tree count comes to 53,721 trees across 4.9 sq mi (12.57 km²), 13 points below the 30% tree-cover level considered healthy for this area, so roughly 40,527 more trees would close the gap.
Air quality detail
Air quality in San Jose today: AQI 55, Moderate
Main pollutant: PM2.5 · Observed Nov 11, 06:00 local time via OpenAQ ground stations, US EPA index. Values in µg/m³.
Ground station · San Jose - Jackson S, 0.6 mi (1 km) away · median of 2 stations
Health signal
Unusually sensitive people should consider limiting long outdoor exertion.
PM2.5
11.0
PM10
—
NO₂
26.6
O₃
2.0
SO₂
—
CO
973.8
Data: OpenAQ · AirNow
- Outdoor exercise
- Fine for most people; unusually sensitive people should take long or hard exercise easier
- Windows
- Fine to open; close them if you are sensitive to pollution
- Mask
- Not needed for most people
- Air purifier
- Worth running if you are sensitive
Over the last 7 days, the CAMS air-quality model put San Jose's daily AQI at 58 on average, from 39 on Nov 4 to an hourly peak of 81 on Nov 8.
Where San Jose stands: the most polluted cities in the world right now · the cleanest
Tree cover detail
Tree cover in San Jose: Critically low
17.1% tree cover against a 30% healthy-neighborhood target, across 4.9 sq mi (12.57 km²).
Trees in this area
53,721
Target trees
94,248
More trees needed
40,527
CO₂ if planted / yr
891.6 t
Deforestation · 2001–2025
How much forest has San Jose lost?
Since 2001, the area within 10 km of San Jose has lost about 41 acres (17 hectares) of forest (about 31 football fields): 3.5% of the forest it had in 2000. Most of it (65%) was deforestation, forest cleared for good, mainly for towns and roads.
2018: satellite photo from July 2018 of a 5 × 5 km area in the city center.
- Forest lost since 2001
- 41 acres (17 ha)about 31 football fields
- Share of its forest
- 3.5%of what there was in 2000
- Cleared for good
- 26 acres (11 ha)deforestation: turned into farms, mines or towns
The worst year was 2008, when about 9 acres (4 hectares) of forest were lost.
Acres of forest lost each year
Show the figures as a table
| Year | Cleared for good | Can grow back | Total |
|---|---|---|---|
| 2001 | under 1 ha | under 1 ha | under 1 ha |
| 2002 | under 1 ha | under 1 ha | under 1 ha |
| 2003 | under 1 ha | under 1 ha | under 1 ha |
| 2004 | under 1 ha | under 1 ha | under 1 ha |
| 2005 | 4 acres (2 ha) | under 1 ha | 6 acres (2 ha) |
| 2006 | under 1 ha | under 1 ha | under 1 ha |
| 2007 | under 1 ha | under 1 ha | under 1 ha |
| 2008 | 8 acres (3 ha) | under 1 ha | 9 acres (4 ha) |
| 2009 | under 1 ha | under 1 ha | 3 acres (1 ha) |
| 2010 | under 1 ha | under 1 ha | under 1 ha |
| 2011 | under 1 ha | under 1 ha | 2 acres (1 ha) |
| 2012 | 3 acres (1 ha) | under 1 ha | 4 acres (2 ha) |
| 2013 | under 1 ha | under 1 ha | under 1 ha |
| 2014 | under 1 ha | under 1 ha | under 1 ha |
| 2015 | under 1 ha | under 1 ha | under 1 ha |
| 2016 | under 1 ha | under 1 ha | under 1 ha |
| 2017 | under 1 ha | under 1 ha | under 1 ha |
| 2018 | under 1 ha | under 1 ha | under 1 ha |
| 2019 | 2 acres (1 ha) | under 1 ha | 2 acres (1 ha) |
| 2020 | under 1 ha | under 1 ha | under 1 ha |
| 2021 | under 1 ha | under 1 ha | under 1 ha |
| 2022 | under 1 ha | under 1 ha | under 1 ha |
| 2023 | under 1 ha | under 1 ha | under 1 ha |
| 2024 | under 1 ha | under 1 ha | under 1 ha |
| 2025 | under 1 ha | under 1 ha | under 1 ha |
What is causing deforestation around San Jose?
- Towns and roadscleared for good64% · 26 acres (11 ha)
- Farms, pasture and plantationscleared for good1.2% · under 1 ha
- Unknown causescause unknown36% · 15 acres (6 ha)
Causes for 2025 are estimates, based on what caused forest loss in the same places up to 2024.
Forest gained and lost, 2000–2020
- Forest in 2000
- 10,100 acres (4,090 ha)
- Forest in 2020
- 11,500 acres (4,670 ha)
- Overall change
- +1,440 acres (583 ha)more forest than in 2000
Comparing satellite maps from 2000 and 2020, the forest around San Jose grew from about 10,100 acres (4,090 hectares) to 11,500 acres (4,670 hectares), a net gain of about 1,440 acres (583 hectares) (+14%). New forest grew on about 1,510 acres (610 hectares), while 68 acres (27 hectares) were lost.
These 2000 and 2020 maps, from the University of Maryland, count any land with trees taller than 5 m as forest, including plantations and orchards. Forest that was cut or burned and had grown back by 2020 counts in both years, so the loss here is smaller than the yearly figures.
These figures cover everything within 10 km of the city center, a wider area than the report above, because forest is usually lost at a city's edges.
Source: Hansen/UMD/Google/USGS/NASA, Global Forest Change (GFC-2025-v1.13); causes: WRI/Google DeepMind drivers of forest loss; both CC BY 4.0, summed by Airleaf for each area. Forest gained and lost 2000–2020: Potapov et al. 2022, UMD GLAD Global Land Cover and Land Use Change, CC BY 4.0. Images: contains modified Copernicus Sentinel data. How it's measured
In the same region
Measured cities near San Jose
Same 2 km radius, same index — so they compare directly.
- Sunnyvale12.9 km
United States
- Tree cover
- 19%
- Air quality
- 21
- Fremont24.7 km
United States
- Tree cover
- 15%
- Air quality
- 29
- Hayward40.1 km
United States
- Tree cover
- 20%
- Air quality
- 29
- San Mateo45.4 km
United States
- Tree cover
- 30%
- Air quality
- 37
- Oakland61.4 km
United States
- Tree cover
- 7%
- Air quality
- 31
- Daly City64.5 km
United States
- Tree cover
- 17%
- Air quality
- 55
Build your own
Compare San Jose with anywhere
This place
San Jose
Use this data
Put San Jose's numbers on your site
Free to embed. Updates itself as the measurement refreshes.
Frequently asked
Questions about San Jose
What is the air quality (AQI) in San Jose right now?
The latest reading for San Jose shows an AQI of 55 (Moderate), measured Nov 11, 06:00 local time by 2 ground monitoring stations via OpenAQ (the median of their readings; the nearest is San Jose - Jackson S, 0.6 mi (1 km) away). The main pollutant is PM2.5. Unusually sensitive people should consider limiting long outdoor exertion.
Is it safe to exercise outside in San Jose today?
At AQI 55 (Moderate): fine for most people; unusually sensitive people should take long or hard exercise easier. Windows: fine to open; close them if you are sensitive to pollution. Masks: not needed for most people. The reading changes through the day, so check again before a long run or ride.
What has the air quality in San Jose been like this week?
Over the last 7 days, the CAMS air-quality model put San Jose's daily AQI at 58 on average, from 39 on Nov 4 to an hourly peak of 81 on Nov 8. No day averaged above 100, the level where the air turns unhealthy for sensitive groups.
How much forest has the area around San Jose lost since 2001?
Since 2001, the area within 10 km of San Jose has lost about 41 acres (17 hectares) of forest (about 31 football fields): 3.5% of the forest it had in 2000. Most of it (65%) was deforestation, forest cleared for good, mainly for towns and roads. Comparing satellite maps from 2000 and 2020, the forest around San Jose grew from about 10,100 acres (4,090 hectares) to 11,500 acres (4,670 hectares), a net gain of about 1,440 acres (583 hectares) (+14%). New forest grew on about 1,510 acres (610 hectares), while 68 acres (27 hectares) were lost.
What is the tree count in San Jose?
San Jose has an estimated 53,721 trees across the 4.9 sq mi (12.57 km²) measured — 17.1% tree cover, 13 percentage points short of the 30% tree-cover target set for this area.
How many more trees does San Jose need?
San Jose needs roughly 40,527 more trees to close a 13-point shortfall against its 30% tree-cover target — about 891.6 t of extra CO₂ absorbed per year once grown.
How are San Jose's air quality and tree cover measured?
Air quality is measured by ground monitoring stations near Ballbach and SOFA, via OpenAQ; the 7-day trend is the Open-Meteo / CAMS model's estimate. Tree cover is measured from Sentinel-2 L2A (ESA Copernicus) via Earth Search satellite imagery at 10 m detail across a 1.2 mi (2 km) radius around Ballbach and SOFA; the tree count is an estimate derived from that cover.
See your own area
What does your neighborhood look like?
Pick any point and radius to get the same air-quality and tree-cover breakdown.
Check my address