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City report · Colorado, United States

Boulder Air quality today

Air quality in Boulder currently reads AQI 14 (Good): Air quality is satisfactory for everyone.

Air quality right now

AQI 14

Good

Main pollutant: Ozone
PM2.5, fine particles (µg/m³)
2.3
tree cover
37.5%
trees in this area
118K
more trees needed
0

Measured across a 1.2 mi (2 km) radius around Goss - Grove, Boulder, CO 80302, USA (4.9 sq mi), from a satellite image of Sep 4, 2026. Lower AQI is better: 0–50 is Good, above 300 is Hazardous.

Boulder · AQI 14 (Good)

Dark green marks tree cover detected inside the study radius.Sentinel-2 L2A (ESA Copernicus) via Earth Search, captured Sep 4, 2026

Boulder's tree count comes to 117,810 trees across 4.9 sq mi (12.57 km²), already at or above the 30% tree-cover level considered healthy for this area.

Air quality detail

Air quality in Boulder today: AQI 14, Good

Main pollutant: Ozone · Observed Nov 11, 08:00 local time via OpenAQ ground stations, US EPA index. Values in µg/m³.

Ground station · Boulder - CU - 2102, 0.2 mi (400 m) away · median of 2 stations

Health signal

Air quality is satisfactory for everyone.

PM2.5

2.3

PM10

9.0

NO₂

—

O₃

31.4

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 Boulder's daily AQI at 45 on average, from 32 on Nov 7 to an hourly peak of 60 on Nov 4.

Last 7 days · model estimateavg 45 · peak 60
Nov 4: AQI 49 (peak 60)Nov 5: AQI 48 (peak 59)Nov 6: AQI 47 (peak 59)Nov 7: AQI 32 (peak 52)Nov 8: AQI 40 (peak 53)Nov 9: AQI 47 (peak 58)Nov 10: AQI 54 (peak 56)
Nov 4Nov 10

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

Tree cover detail

Tree cover in Boulder: Healthy tree cover

37.5% tree cover against a 30% healthy-neighborhood target, across 4.9 sq mi (12.57 km²).

Target reached

Trees in this area

117,810

Target trees

117,810

More trees needed

0

CO₂ if planted / yr

0 kg

Deforestation · 2001–2025

How much forest has Boulder lost?

Since 2001, the area within 10 km of Boulder has lost about 675 acres (273 hectares) of forest (about 510 football fields): 5.5% of the forest it had in 2000. Most of it was lost to wildfires, so much of it can grow back. About 6 acres (3 hectares) (under 1%) was deforestation: forest cleared for good for farms, mines or towns.

Satellite image of the area around Boulder, July 2017

2017: satellite photo from July 2017 of a 5 × 5 km area in the city center.

Forest lost since 2001
675 acres (273 ha)about 510 football fields
Share of its forest
5.5%of what there was in 2000
Cleared for good
6 acres (3 ha)deforestation: turned into farms, mines or towns

The worst year was 2001, when about 183 acres (74 hectares) of forest were lost, mostly to wildfires.

Forest lost each year around Boulder, 2001–2025

Acres of forest lost each year

Forest lost each year around Boulder, 2001–2025. Use the left and right arrow keys to read each year.183

Show the figures as a table
Forest lost each year around Boulder, 2001–2025
YearCleared for goodCan grow backTotal
2001under 1 ha183 acres (74 ha)183 acres (74 ha)
2002under 1 haunder 1 haunder 1 ha
2003under 1 ha4 acres (2 ha)4 acres (2 ha)
2004under 1 ha7 acres (3 ha)7 acres (3 ha)
20052 acres (1 ha)4 acres (2 ha)7 acres (3 ha)
2006under 1 ha4 acres (2 ha)4 acres (2 ha)
2007under 1 ha11 acres (5 ha)11 acres (5 ha)
2008under 1 ha18 acres (7 ha)18 acres (7 ha)
2009under 1 haunder 1 haunder 1 ha
2010under 1 ha77 acres (31 ha)77 acres (31 ha)
2011under 1 ha172 acres (70 ha)172 acres (70 ha)
2012under 1 ha92 acres (37 ha)92 acres (37 ha)
2013under 1 ha19 acres (8 ha)19 acres (8 ha)
2014under 1 ha17 acres (7 ha)18 acres (7 ha)
2015under 1 ha9 acres (4 ha)9 acres (4 ha)
2016under 1 haunder 1 haunder 1 ha
2017under 1 ha11 acres (5 ha)12 acres (5 ha)
2018under 1 haunder 1 haunder 1 ha
2019under 1 ha4 acres (2 ha)4 acres (2 ha)
2020under 1 haunder 1 haunder 1 ha
2021under 1 haunder 1 haunder 1 ha
2022under 1 haunder 1 haunder 1 ha
2023under 1 ha11 acres (4 ha)12 acres (5 ha)
2024under 1 haunder 1 haunder 1 ha
2025under 1 ha21 acres (8 ha)21 acres (8 ha)

What is causing deforestation around Boulder?

  • Wildfirescan grow back85% · 573 acres (232 ha)
  • Loggingcan grow back8.9% · 60 acres (24 ha)
  • Storms, floods and other natural causescan grow back2% · 13 acres (5 ha)

Also: towns and roads, farms, pasture and plantations, 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
26,000 acres (10,500 ha)
Forest in 2020
25,900 acres (10,500 ha)
Overall change
−136 acres (55 ha)less forest than in 2000

Comparing satellite maps from 2000 and 2020, the forest around Boulder stayed about the same size, at about 25,900 acres (10,500 hectares): new forest grew on about 630 acres (255 hectares), and about 766 acres (310 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 Boulder

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

  • Arvada

    United States

    28.3 km
    Tree cover
    21%
    Air quality
    32
  • Thornton

    United States

    30.3 km
    Tree cover
    10%
    Air quality
    132
  • Lakewood

    United States

    38.1 km
    Tree cover
    27%
    Air quality
    32
  • Denver

    United States

    39.2 km
    Tree cover
    13%
    Air quality
    29
  • Aurora

    United States

    49.1 km
    Tree cover
    14%
    Air quality
    23
  • Centennial

    United States

    59.0 km
    Tree cover
    19%
    Air quality
    34

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

Questions about Boulder

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

The latest reading for Boulder shows an AQI of 14 (Good), measured Nov 11, 08:00 local time by 2 ground monitoring stations via OpenAQ (the median of their readings; the nearest is Boulder - CU - 2102, 0.2 mi (400 m) away). The main pollutant is Ozone. Air quality is satisfactory for everyone.

Is it safe to exercise outside in Boulder today?

At AQI 14 (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 Boulder been like this week?

Over the last 7 days, the CAMS air-quality model put Boulder's daily AQI at 45 on average, from 32 on Nov 7 to an hourly peak of 60 on Nov 4. No day averaged above 100, the level where the air turns unhealthy for sensitive groups.

How much forest has the area around Boulder lost since 2001?

Since 2001, the area within 10 km of Boulder has lost about 675 acres (273 hectares) of forest (about 510 football fields): 5.5% of the forest it had in 2000. Most of it was lost to wildfires, so much of it can grow back. About 6 acres (3 hectares) (under 1%) was deforestation: forest cleared for good for farms, mines or towns. Comparing satellite maps from 2000 and 2020, the forest around Boulder stayed about the same size, at about 25,900 acres (10,500 hectares): new forest grew on about 630 acres (255 hectares), and about 766 acres (310 hectares) were lost.

What is the tree count in Boulder?

Boulder has an estimated 117,810 trees across the 4.9 sq mi (12.57 km²) measured — 37.5% tree cover, already past the 30% tree-cover target set for this area.

How many more trees does Boulder need?

Boulder has already reached its tree-cover target, so no additional trees are needed to close the gap.

How are Boulder's air quality and tree cover measured?

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

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