City report · Saitama, Japan
Koshigaya Air quality today
Air quality in Koshigaya currently reads AQI 53 (Moderate): Unusually sensitive people should consider limiting long outdoor exertion.
AQI 53
Air quality right now
Moderate
- PM2.5, fine particles (µg/m³)
- 10.0
- tree cover
- 3.9%
- trees in this area
- 12.2K
- more trees needed
- 81.9K
Measured across a 2 km radius around 2 Chome-7 Koshigaya, Saitama 343-0813, Japan (12.57 km²), from a satellite image of Jul 25, 2026. Lower AQI is better: 0–50 is Good, above 300 is Hazardous.
Koshigaya · AQI 53 (Moderate)
Koshigaya's tree count comes to 12,240 trees across 12.56 km² of land, 26 points below the 30% tree-cover level considered healthy for this area, so roughly 81,914 more trees would close the gap.
Air quality detail
Air quality in Koshigaya today: AQI 53, Moderate
Main pollutant: PM2.5 · Observed Nov 12, 02:00 local time via OpenAQ ground stations, US EPA index. Values in µg/m³.
Ground station · 越谷市千間台西4-2, 5.4 km away · median of 11 stations
Health signal
Unusually sensitive people should consider limiting long outdoor exertion.
PM2.5
10.0
PM10
—
NO₂
52.7
O₃
—
SO₂
2.6
CO
343.7
Data: OpenAQ · Ministry of the Environment Air Pollutant Wide Area Monitoring System
- 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 Koshigaya's daily AQI at 56 on average, from 26 on Nov 7 to an hourly peak of 147 on Nov 5.
Where Koshigaya stands: the most polluted cities in the world right now · the cleanest
Tree cover detail
Tree cover in Koshigaya: Critically low
3.9% tree cover against a 30% healthy-neighborhood target, across 12.56 km² of land.
Trees in this area
12,240
Target trees
94,154
More trees needed
81,914
CO₂ if planted / yr
1,802 t
Deforestation · 2001–2025
How much forest has Koshigaya lost?
Since 2001, the area within 10 km of Koshigaya has lost about 20 hectares of forest (about 28 football pitches): 3.5% of the forest it had in 2000. Most of it (72%) was deforestation, forest cleared for good, mainly for towns and roads.
2018: satellite photo from August 2018 of a 5 × 5 km area in the city center.
- Forest lost since 2001
- 20 haabout 28 football pitches
- Share of its forest
- 3.5%of what there was in 2000
- Cleared for good
- 14 hadeforestation: turned into farms, mines or towns
The worst year was 2006, when about 6 hectares of forest were lost.
Hectares 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 | 1 ha |
| 2002 | under 1 ha | 1 ha | 1 ha |
| 2003 | under 1 ha | under 1 ha | under 1 ha |
| 2004 | under 1 ha | under 1 ha | under 1 ha |
| 2005 | under 1 ha | under 1 ha | under 1 ha |
| 2006 | 5 ha | under 1 ha | 6 ha |
| 2007 | under 1 ha | under 1 ha | under 1 ha |
| 2008 | under 1 ha | under 1 ha | under 1 ha |
| 2009 | 2 ha | under 1 ha | 3 ha |
| 2010 | under 1 ha | under 1 ha | 2 ha |
| 2011 | under 1 ha | under 1 ha | under 1 ha |
| 2012 | 1 ha | under 1 ha | 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 | under 1 ha | under 1 ha | under 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 Koshigaya?
- Towns and roadscleared for good72% · 14 ha
- Unknown causescause unknown27% · 5 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
- 1,440 ha
- Forest in 2020
- 1,420 ha
- Overall change
- −20 haless forest than in 2000
Comparing satellite maps from 2000 and 2020, the forest around Koshigaya stayed about the same size, at about 1,420 hectares: new forest grew on about 80 hectares, and about 101 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
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Frequently asked
Questions about Koshigaya
What is the air quality (AQI) in Koshigaya right now?
The latest reading for Koshigaya shows an AQI of 53 (Moderate), measured Nov 12, 02:00 local time by 11 ground monitoring stations via OpenAQ (the median of their readings; the nearest is 越谷市千間台西4-2, 5.4 km away). The main pollutant is PM2.5. Unusually sensitive people should consider limiting long outdoor exertion.
Is it safe to exercise outside in Koshigaya 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 Koshigaya been like this week?
Over the last 7 days, the CAMS air-quality model put Koshigaya's daily AQI at 56 on average, from 26 on Nov 7 to an hourly peak of 147 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 Koshigaya lost since 2001?
Since 2001, the area within 10 km of Koshigaya has lost about 20 hectares of forest (about 28 football pitches): 3.5% of the forest it had in 2000. Most of it (72%) was deforestation, forest cleared for good, mainly for towns and roads. Comparing satellite maps from 2000 and 2020, the forest around Koshigaya stayed about the same size, at about 1,420 hectares: new forest grew on about 80 hectares, and about 101 hectares were lost.
What is the tree count in Koshigaya?
Koshigaya has an estimated 12,240 trees across the 12.56 km² of land measured — 3.9% tree cover, 26 percentage points short of the 30% tree-cover target set for this area.
How many more trees does Koshigaya need?
Koshigaya needs roughly 81,914 more trees to close a 26-point shortfall against its 30% tree-cover target — about 1,802 t of extra CO₂ absorbed per year once grown.
How are Koshigaya's air quality and tree cover measured?
Air quality is measured by ground monitoring stations near 2 Chome-7 Koshigaya, 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 2 km radius around 2 Chome-7 Koshigaya; the tree count is an estimate derived from that cover.
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