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City report · United States

Honolulu Air quality today

Air quality in Honolulu currently reads AQI 53 (Moderate): Unusually sensitive people should consider limiting long outdoor exertion.

Air quality right now

AQI 53

Moderate

Main pollutant: PM2.5
PM2.5, fine particles (µg/m³)
10.1
tree cover
20.9%
trees in this area
55.0K
more trees needed
24.0K

Measured across a 1.2 mi (2 km) radius around Downtown, Honolulu, HI, USA (4.9 sq mi), from a satellite image of Oct 16, 2026. Lower AQI is better: 0–50 is Good, above 300 is Hazardous.

Honolulu · AQI 53 (Moderate)

Dark green marks tree cover detected inside the study radius.Sentinel-2 L2A (ESA Copernicus) via Earth Search, captured Oct 16, 2026

Honolulu's tree count comes to 55,022 trees across 4.1 sq mi (10.53 km²) of land, 9 points below the 30% tree-cover level considered healthy for this area, so roughly 23,957 more trees would close the gap.

Air quality detail

Air quality in Honolulu today: AQI 53, Moderate

Main pollutant: PM2.5 · Observed Nov 10, 03:00 local time via Open-Meteo / CAMS, US EPA index. Values in µg/m³.

Model estimate · no ground station nearby

Health signal

Unusually sensitive people should consider limiting long outdoor exertion.

PM2.5

10.1

PM10

17.3

NO₂

0.6

O₃

76.0

SO₂

0.5

CO

108.0

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 Honolulu's daily AQI at 49 on average, from 41 on Nov 5 to an hourly peak of 56 on Nov 6.

Last 7 daysavg 49 · peak 56
Nov 4: AQI 45 (peak 55)Nov 5: AQI 41 (peak 53)Nov 6: AQI 53 (peak 56)Nov 7: AQI 50 (peak 54)Nov 8: AQI 50 (peak 54)Nov 9: AQI 48 (peak 53)Nov 10: AQI 53 (peak 53)
Nov 4Nov 10

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

Tree cover detail

Tree cover in Honolulu: Below target

20.9% tree cover against a 30% healthy-neighborhood target, across 4.1 sq mi (10.53 km²) of land.

9 points below target

Trees in this area

55,022

Target trees

78,979

More trees needed

23,957

CO₂ if planted / yr

527.1 t

Deforestation · 2001–2025

How much forest has Honolulu lost?

Since 2001, the area within 10 km of Honolulu has lost about 198 acres (80 hectares) of forest (about 150 football fields): under 1% of the forest it had in 2000. The biggest cause was storms, floods and other natural causes (40%), after which forest can grow back. About 83 acres (34 hectares) (42%) was deforestation: forest cleared for good for farms, mines or towns.

Satellite image of the area around Honolulu, September 2018

2018: satellite photo from September 2018 of a 5 × 5 km area in the city center.

Forest lost since 2001
198 acres (80 ha)about 150 football fields
Share of its forest
under 1%of what there was in 2000
Cleared for good
83 acres (34 ha)deforestation: turned into farms, mines or towns

The worst year was 2012, when about 56 acres (23 hectares) of forest were lost.

Forest lost each year around Honolulu, 2001–2025

Acres of forest lost each year

Forest lost each year around Honolulu, 2001–2025. Use the left and right arrow keys to read each year.56.3

Show the figures as a table
Forest lost each year around Honolulu, 2001–2025
YearCleared for goodCan grow backTotal
2001under 1 ha4 acres (2 ha)4 acres (2 ha)
2002under 1 ha3 acres (1 ha)3 acres (1 ha)
2003under 1 haunder 1 haunder 1 ha
2004under 1 ha6 acres (2 ha)6 acres (3 ha)
2005under 1 ha2 acres (1 ha)3 acres (1 ha)
2006under 1 ha4 acres (2 ha)4 acres (2 ha)
2007under 1 ha3 acres (1 ha)3 acres (1 ha)
2008under 1 ha6 acres (2 ha)8 acres (3 ha)
20095 acres (2 ha)9 acres (4 ha)14 acres (6 ha)
2010under 1 haunder 1 haunder 1 ha
2011under 1 ha11 acres (4 ha)12 acres (5 ha)
201246 acres (19 ha)10 acres (4 ha)56 acres (23 ha)
2013under 1 haunder 1 haunder 1 ha
2014under 1 ha8 acres (3 ha)10 acres (4 ha)
20158 acres (3 ha)9 acres (4 ha)18 acres (7 ha)
2016under 1 haunder 1 haunder 1 ha
2017under 1 ha5 acres (2 ha)8 acres (3 ha)
201812 acres (5 ha)23 acres (9 ha)35 acres (14 ha)
2019under 1 haunder 1 haunder 1 ha
2020under 1 ha5 acres (2 ha)6 acres (2 ha)
2021under 1 haunder 1 haunder 1 ha
2022under 1 haunder 1 haunder 1 ha
2023under 1 haunder 1 haunder 1 ha
2024under 1 haunder 1 haunder 1 ha
2025under 1 haunder 1 haunder 1 ha

What is causing deforestation around Honolulu?

  • Storms, floods and other natural causescan grow back40% · 79 acres (32 ha)
  • Towns and roadscleared for good31% · 61 acres (25 ha)
  • Farms, pasture and plantationscleared for good11% · 23 acres (9 ha)

Also: 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
22,600 acres (9,140 ha)
Forest in 2020
22,500 acres (9,120 ha)
Overall change
−54 acres (22 ha)less forest than in 2000

Comparing satellite maps from 2000 and 2020, the forest around Honolulu stayed about the same size, at about 22,500 acres (9,120 hectares): new forest grew on about 58 acres (24 hectares), and about 114 acres (46 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 Honolulu

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

  • Majuro

    Marshall Islands

    3662.1 km
    Tree cover
    11%
    Air quality
    53
  • Daly City

    United States

    3848.0 km
    Tree cover
    17%
    Air quality
    55
  • Santa Rosa

    United States

    3853.4 km
    Tree cover
    26%
    Air quality
    30
  • San Francisco

    United States

    3853.9 km
    Tree cover
    6%
    Air quality
    51
  • San Mateo

    United States

    3854.5 km
    Tree cover
    30%
    Air quality
    37
  • Tarawa

    Kiribati

    3863.0 km
    Tree cover
    22%
    Air quality
    14

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

Questions about Honolulu

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

The latest reading for Honolulu shows an AQI of 53 (Moderate), observed Nov 10, 03:00 local time via Open-Meteo / CAMS, US EPA index. The main pollutant is PM2.5. Unusually sensitive people should consider limiting long outdoor exertion.

Is it safe to exercise outside in Honolulu today?

At AQI 53 (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 Honolulu been like this week?

Over the last 7 days, the CAMS air-quality model put Honolulu's daily AQI at 49 on average, from 41 on Nov 5 to an hourly peak of 56 on Nov 6. No day averaged above 100, the level where the air turns unhealthy for sensitive groups.

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

Since 2001, the area within 10 km of Honolulu has lost about 198 acres (80 hectares) of forest (about 150 football fields): under 1% of the forest it had in 2000. The biggest cause was storms, floods and other natural causes (40%), after which forest can grow back. About 83 acres (34 hectares) (42%) was deforestation: forest cleared for good for farms, mines or towns. Comparing satellite maps from 2000 and 2020, the forest around Honolulu stayed about the same size, at about 22,500 acres (9,120 hectares): new forest grew on about 58 acres (24 hectares), and about 114 acres (46 hectares) were lost.

What is the tree count in Honolulu?

Honolulu has an estimated 55,022 trees across the 4.1 sq mi (10.53 km²) of land measured — 20.9% tree cover, 9 percentage points short of the 30% tree-cover target set for this area.

How many more trees does Honolulu need?

Honolulu needs roughly 23,957 more trees to close a 9-point shortfall against its 30% tree-cover target — about 527.1 t of extra CO₂ absorbed per year once grown.

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

Air quality comes from ground monitoring stations via OpenAQ where one reports nearby, and otherwise, as here, from the Open-Meteo / CAMS model, which may differ from street-level monitors. 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 Downtown; the tree count is an estimate derived from that cover.

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