Air quality comparison · Japan, 40 km apart
Fukushima vs Kōriyama Air quality index (AQI) today
Fukushima has cleaner air than Kōriyama right now: AQI 6 (Good) against 39 (Good).
Both sit in the same EPA band, so the health advice is the same for each today. Over the past 7 days, on modeled daily averages, both averaged AQI 24. Fukushima has lost more forest since 2001. Fukushima has more tree cover.
Updated . Lower is better on the US EPA index: 0–50 is Good, above 300 is Hazardous. Measured by Airleaf.
Fukushima6Kōriyama39
Head to head
Fukushima vs Kōriyama at a glance
Fukushima is ahead on 4 of 6 measures, and Kōriyama on 1. The better figure in each row is marked.
| Fukushima | Kōriyama | |
|---|---|---|
| Air quality nowUS AQI. Lower is better. | 6 (better) | 39 |
| PM2.5Fine particles, µg/m³. | 1.3 (better) | 7 |
| Past week's averageUS AQI, 7 days. | 24 | 24 |
| Forest lost since 2001Within 10 km of the center. | 660 ha | 275 ha (better) |
| Tree coverWithin 2 km of the center. | 14.8% (better) | 5.5% |
| Trees still neededTo reach a healthy canopy. | 46.7K (better) | 76.6K |
Air quality today
What is the air like in Fukushima and Kōriyama right now?
Fukushima has cleaner air than Kōriyama right now: AQI 6 (Good) against 39 (Good). PM2.5 is setting the index in both.
Kōriyama is read from a nearby ground station and Fukushima is a model estimate, so the two are not quite like for like.
FukushimaKōriyama
Concentrations at the same moment as the index above, for the pollutants both places report. Lower is better. The dark marks on the PM2.5 and PM10 rows show the WHO's 24-hour guidelines (15 and 45 µg/m³).
Fukushima: Estimate · model corrected with 45 station cities within 225 km, e.g. Koriyama and Aizuwakamatsu. Data: Open-Meteo / CAMS, corrected with 45 ground-station cities within 225 km, US EPA index.
Kōriyama: Ground station · 郡山市台新１－８０４, 3.7 km away · median of 3 stations. Data: OpenAQ · Ministry of the Environment Air Pollutant Wide Area Monitoring System.
The past week
Which had cleaner air over the past 7 days?
Over the past 7 days, on modeled daily averages, both averaged AQI 24. The two are close enough that the air model behind these daily figures barely separates them, so their lines nearly overlap.
- Cleaner days
- Fukushima0Kōriyama0
- Average AQI
- Fukushima24Kōriyama24
- Worst day, AQI
- Fukushima45Kōriyama45
The daily numbers (7 days)
| Day | Fukushima | Kōriyama |
|---|---|---|
| Nov 5 | 18 | 18 |
| Nov 6 | 35 | 35 |
| Nov 7 | 7 | 7 |
| Nov 8 | 26 | 26 |
| Nov 9 | 45 | 45 |
| Nov 10 | 19 | 19 |
| Nov 11 | 19 | 19 |
Daily averages from the CAMS atmospheric model for both places, so the week compares like with like. They can differ from today's reading at the top of the page wherever that comes from a ground station.
What it means today
Is it safe to go outside in Fukushima and Kōriyama today?
Air quality is satisfactory for everyone. Both are in the same EPA band today (Good), so the advice is the same.
Exercise outdoors
A good day to be active outside.
Windows
Open them to air the house.
Masks
Not needed.
Air purifier
Not needed.
Against everywhere else
How do Fukushima and Kōriyama compare with the rest of the world?
Right now Fukushima's air is cleaner than 98% of the 5,420 places Airleaf tracks, and Kōriyama's is cleaner than 71%. Within Japan, that is 96% and 44% of its 207 measured places.
Cleaner air than…
- Fukushima
- Beats 98%
- Kōriyama
- Beats 71%
More tree cover than…
- Fukushima
- Beats 34%
- Kōriyama
- Beats 11%
Includes model estimates as well as station readings, so it can differ from our most polluted and cleanest air rankings, which use station readings only.
Deforestation · 2001–2025
Which has lost more forest, Fukushima or Kōriyama?
Fukushima has lost more: about 660 ha of forest within 10 km of its center from 2001 to 2025, against 275 ha around Kōriyama. 166 ha of that was cleared for good, for farms, mines or towns.
Measured within 10 km of each center, from the yearly satellite maps of forest loss: a wider circle than the one for tree cover, because forest is usually lost at a city's edges.
Worst year: 2001, with 92 ha lost.
Worst year: 2012, with 34 ha lost.
| Fukushima | Kōriyama | |
|---|---|---|
| Forest lost since 2001Cleared, burned or logged. | 660 ha | 275 ha (better) |
| Share of its forestOf what it had in 2000. | 5.3% | 4.6% (better) |
| Cleared for goodTurned into farms, mines or towns. | 166 ha | 131 ha (better) |
| Recent trend2021–2025 against the five years before. | Too little to call | Too little to call |
| Main known cause | Logging (73%) | Logging (48%) |
Satellite timelapses
Watch both change, year by year
A clear satellite photo a year of the land around each city. Press play, turn on the forest cleared since the first year, or drag the before and after.
Fukushima
2017: satellite photo from July 2017 of a 5 × 5 km area about 6 km east of the city center.
Kōriyama
2017: satellite photo from July 2017 of a 5 × 5 km area in the city center.
Trees
Which has more trees, Fukushima or Kōriyama?
Fukushima has more tree cover: 14.8% of the land within 2 km of its center against 5.5% around Kōriyama, or about 45,519 trees against 17,192.
The dark mark is each place's canopy target: 30% of the land, raised where air quality is poor.
| Fukushima | Kōriyama | |
|---|---|---|
| Trees standingEstimated from the canopy area. | 45.5K (better) | 17.2K |
| Trees still neededTo reach the target. Fewer is better. | 46.7K (better) | 76.6K |
| CO₂ absorbed each yearBy the trees already standing. | 1.0M kg (better) | 378K kg |
Tree cover on the satellite image
The same 2 km radius around each center, with the tree cover the satellite found marked on it.
Reading these numbers
How this comparison is made
Air quality index
The US EPA index, computed from current pollutant concentrations: ground stations where a place has them nearby, and the CAMS atmospheric model everywhere else. It moves hour to hour, so it is a snapshot rather than a verdict on either place. The guideline marks are from the WHO's 2021 air quality guidelines.
Trees and forest
Tree cover is the share of ground under canopy within 2 km of each center, read from Sentinel-2 satellite imagery at 10 m detail. It measures that circle, not the whole municipality, which is what makes the two comparable. Forest loss comes from the University of Maryland's Global Forest Change maps.
More on the method on the About Airleaf page.
Frequently asked
Fukushima vs Kōriyama: your questions answered
Is Fukushima cleaner than Kōriyama?
On air quality, yes, right now: Fukushima reads AQI 6 against 39, a gap of 33 points on the US EPA index. This is a live reading rather than an annual average, so it can reverse within a day. Over the past 7 days, on modeled daily averages, both averaged AQI 24.
Is it safe to exercise outdoors in Fukushima and Kōriyama today?
The advice is the same for both today. Air quality is satisfactory for everyone. Fukushima reads AQI 6 and Kōriyama reads AQI 39.
Which has lost more forest, Fukushima or Kōriyama?
Fukushima has lost more: about 660 ha of forest within 10 km of its center from 2001 to 2025, against 275 ha around Kōriyama. 166 ha of that was cleared for good, for farms, mines or towns.
Which has more trees, Fukushima or Kōriyama?
Fukushima has more tree cover: 14.8% of the land within 2 km of its center against 5.5% around Kōriyama, or about 45,519 trees against 17,192. Both figures describe the same-sized circle of ground around each center, not the whole municipality.
How many more trees do Fukushima and Kōriyama need?
Fukushima needs about 46,749 more to reach its canopy target of 30%, and Kōriyama about 76,584 to reach 30%. The target starts at 30% of the land and rises where air quality is poor.
Why can two places 40 km apart read differently?
Air changes over short distances with traffic, industry, wind and hills, and each reading comes from the nearest ground stations or, where there are none, from a regional model. A gap of a few points between neighbors is within normal variation, while a gap that crosses an EPA band is worth noticing.
Are Fukushima and Kōriyama measured the same way?
The method is the same: the US EPA index for air, and Sentinel-2 satellite imagery at 10 m detail over an identical radius for trees. Kōriyama is read from a nearby ground station and Fukushima is a model estimate, so the two are not quite like for like. Nothing is adjusted for population, city limits or climate.
How often does the Fukushima vs Kōriyama comparison update?
The air readings refresh about once an hour, and each reading's local time is shown at the top of the page. Tree cover comes from the latest clear satellite image of each area (Aug 24, 2026 and Aug 24, 2026), and the forest figures are published yearly.
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