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City report · California, United States

Simi Valley Air quality today

Air quality in Simi Valley currently reads AQI 17 (Good): Air quality is satisfactory for everyone.

Air quality right now

AQI 17

Good

Main pollutant: PM2.5
PM2.5, fine particles (µg/m³)
3.0
tree cover
14.2%
trees in this area
44.6K
more trees needed
49.6K

Measured across a 1.2 mi (2 km) radius around Simi Valley, CA, USA (4.9 sq mi), from a satellite image of Sep 14, 2026. Lower AQI is better: 0–50 is Good, above 300 is Hazardous.

Simi Valley · AQI 17 (Good)

Dark green marks tree cover detected inside the study radius.Sentinel-2 L2A (ESA Copernicus) via Earth Search, captured Sep 14, 2026

Simi Valley's tree count comes to 44,566 trees across 4.8 sq mi (12.56 km²) of land, 16 points below the 30% tree-cover level considered healthy for this area, so roughly 49,588 more trees would close the gap.

Air quality detail

Air quality in Simi Valley today: AQI 17, Good

Main pollutant: PM2.5 · Observed Nov 11, 06:00 local time via OpenAQ ground stations, US EPA index. Values in µg/m³.

Ground station · Simi Valley - Cochra, 5.6 mi (9 km) away

Health signal

Air quality is satisfactory for everyone.

PM2.5

3.0

PM10

—

NO₂

26.3

O₃

21.6

SO₂

—

CO

—

Data: OpenAQ · AirNow

Outdoor exercise
A good day to be active outside
Windows
Open them to air the house
Mask
Not needed
Air purifier
Not needed

Over the last 7 days, the CAMS air-quality model put Simi Valley's daily AQI at 39 on average, from 30 on Nov 7 to an hourly peak of 58 on Nov 5.

Last 7 days · model estimateavg 39 · peak 58
Nov 4: AQI 47 (peak 55)Nov 5: AQI 43 (peak 58)Nov 6: AQI 32 (peak 55)Nov 7: AQI 30 (peak 52)Nov 8: AQI 34 (peak 56)Nov 9: AQI 41 (peak 56)Nov 10: AQI 49 (peak 57)
Nov 4Nov 10

Where Simi Valley stands: the most polluted cities in the world right now · the cleanest

Tree cover detail

Tree cover in Simi Valley: Critically low

14.2% tree cover against a 30% healthy-neighborhood target, across 4.8 sq mi (12.56 km²) of land.

16 points below target

Trees in this area

44,566

Target trees

94,154

More trees needed

49,588

CO₂ if planted / yr

1,091 t

Deforestation · 2001–2025

How much forest has Simi Valley lost?

Since 2001, the area within 10 km of Simi Valley has lost about 4,330 acres (1,750 hectares) of forest (about 3,300 football fields): 76% of the forest it had in 2000. Most of it was lost to wildfires, so much of it can grow back. About 165 acres (67 hectares) (3.8%) was deforestation: forest cleared for good for farms, mines or towns.

Satellite image of the area around Simi Valley, August 2017

2017: satellite photo from August 2017 of a 5 × 5 km area about 6 km south of the city center.

Forest lost since 2001
4,330 acres (1,750 ha)about 3,300 football fields
Share of its forest
76%of what there was in 2000
Cleared for good
165 acres (67 ha)deforestation: turned into farms, mines or towns

The worst year was 2005, when about 1,680 acres (680 hectares) of forest were lost, mostly to wildfires.

Forest lost each year around Simi Valley, 2001–2025

Acres of forest lost each year

Forest lost each year around Simi Valley, 2001–2025. Use the left and right arrow keys to read each year.1.68K

Show the figures as a table
Forest lost each year around Simi Valley, 2001–2025
YearCleared for goodCan grow backTotal
2001under 1 ha8 acres (3 ha)9 acres (4 ha)
200218 acres (7 ha)76 acres (31 ha)94 acres (38 ha)
200328 acres (12 ha)1,390 acres (564 ha)1,420 acres (575 ha)
200428 acres (11 ha)417 acres (169 ha)445 acres (180 ha)
20057 acres (3 ha)1,670 acres (677 ha)1,680 acres (680 ha)
20066 acres (2 ha)92 acres (37 ha)98 acres (40 ha)
200710 acres (4 ha)10 acres (4 ha)21 acres (8 ha)
200828 acres (11 ha)22 acres (9 ha)50 acres (20 ha)
2009under 1 haunder 1 ha2 acres (1 ha)
20103 acres (1 ha)under 1 ha4 acres (2 ha)
20119 acres (4 ha)6 acres (3 ha)15 acres (6 ha)
20125 acres (2 ha)6 acres (3 ha)12 acres (5 ha)
2013under 1 haunder 1 haunder 1 ha
20142 acres (1 ha)under 1 ha2 acres (1 ha)
2015under 1 ha7 acres (3 ha)8 acres (3 ha)
20164 acres (2 ha)3 acres (1 ha)7 acres (3 ha)
2017under 1 ha3 acres (1 ha)3 acres (1 ha)
2018under 1 ha197 acres (80 ha)198 acres (80 ha)
2019under 1 ha248 acres (100 ha)250 acres (101 ha)
2020under 1 haunder 1 haunder 1 ha
2021under 1 haunder 1 haunder 1 ha
2022under 1 haunder 1 haunder 1 ha
2023under 1 haunder 1 haunder 1 ha
20246 acres (2 ha)under 1 ha7 acres (3 ha)
2025under 1 haunder 1 haunder 1 ha

What is causing deforestation around Simi Valley?

  • Wildfirescan grow back96% · 4,160 acres (1,680 ha)
  • Farms, pasture and plantationscleared for good2.4% · 104 acres (42 ha)
  • Towns and roadscleared for good1.3% · 58 acres (24 ha)

Also: mining and energy, unknown causes.

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
15,800 acres (6,410 ha)
Forest in 2020
14,300 acres (5,790 ha)
Overall change
−1,540 acres (622 ha)less forest than in 2000

Comparing satellite maps from 2000 and 2020, the forest around Simi Valley shrank from about 15,800 acres (6,410 hectares) to 14,300 acres (5,790 hectares), a net loss of about 1,540 acres (622 hectares) (−9.7%). New forest grew on about 551 acres (223 hectares), but 2,090 acres (846 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 Simi Valley

Same 2 km radius, same index — so they compare directly.

  • Thousand Oaks

    United States

    12.1 km
    Tree cover
    20%
    Air quality
    39
  • Valencia

    United States

    25.0 km
    Tree cover
    11%
    Air quality
    13
  • Santa Clarita

    United States

    25.8 km
    Tree cover
    22%
    Air quality
    13
  • Van Nuys

    United States

    31.9 km
    Tree cover
    19%
    Air quality
    34
  • Oxnard

    United States

    37.2 km
    Tree cover
    5%
    Air quality
    23
  • Burbank

    United States

    44.5 km
    Tree cover
    15%
    Air quality
    34

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Simi Valley air quality (AQI) and tree cover — measured by Airleaf
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Frequently asked

Questions about Simi Valley

What is the air quality (AQI) in Simi Valley right now?

The latest reading for Simi Valley shows an AQI of 17 (Good), measured Nov 11, 06:00 local time by the Simi Valley - Cochra ground monitoring station, 5.6 mi (9 km) away, via OpenAQ. The main pollutant is PM2.5. Air quality is satisfactory for everyone.

Is it safe to exercise outside in Simi Valley today?

At AQI 17 (Good): a good day to be active outside. Windows: open them to air the house. Masks: not needed. The reading changes through the day, so check again before a long run or ride.

What has the air quality in Simi Valley been like this week?

Over the last 7 days, the CAMS air-quality model put Simi Valley's daily AQI at 39 on average, from 30 on Nov 7 to an hourly peak of 58 on Nov 5. No day averaged above 100, the level where the air turns unhealthy for sensitive groups.

How much forest has the area around Simi Valley lost since 2001?

Since 2001, the area within 10 km of Simi Valley has lost about 4,330 acres (1,750 hectares) of forest (about 3,300 football fields): 76% of the forest it had in 2000. Most of it was lost to wildfires, so much of it can grow back. About 165 acres (67 hectares) (3.8%) was deforestation: forest cleared for good for farms, mines or towns. Comparing satellite maps from 2000 and 2020, the forest around Simi Valley shrank from about 15,800 acres (6,410 hectares) to 14,300 acres (5,790 hectares), a net loss of about 1,540 acres (622 hectares) (−9.7%). New forest grew on about 551 acres (223 hectares), but 2,090 acres (846 hectares) were lost.

What is the tree count in Simi Valley?

Simi Valley has an estimated 44,566 trees across the 4.8 sq mi (12.56 km²) of land measured — 14.2% tree cover, 16 percentage points short of the 30% tree-cover target set for this area.

How many more trees does Simi Valley need?

Simi Valley needs roughly 49,588 more trees to close a 16-point shortfall against its 30% tree-cover target — about 1,091 t of extra CO₂ absorbed per year once grown.

How are Simi Valley's air quality and tree cover measured?

Air quality is measured by ground monitoring stations near Simi Valley, 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 Simi Valley; the tree count is an estimate derived from that cover.

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