Country comparison · 364 cities measured
South Korea vs United States Air quality index (AQI) and deforestation
United States has cleaner air than South Korea right now: its cities average AQI 42 against 82.
At ground stations alone, which measure rather than estimate, the averages are South Korea 82 (56 cities) and United States 43 (279 cities). United States has lost more forest since 2001. South Korea has more tree cover in its cities.
Average of 56 cities
AQI 82
Moderate
Cleaner on average
- At ground stations
- AQI 82
- Tree cover
- 28.4%
- Forest lost since 2001
- 436,000 ha
Average of 308 cities
AQI 42
Good
Cleaner on average
- At ground stations
- AQI 43
- Tree cover
- 25.1%
- Forest lost since 2001
- 126 million acres (51 million ha)
Updated . Lower is better on the US EPA index: 0–50 is Good, above 300 is Hazardous. Measured by Airleaf.
South Korea82United States42
Head to head
South Korea vs United States at a glance
South Korea and United States are level, each ahead on 3 of 6 measures. The better figure in each row is marked.
| South Korea | United States | |
|---|---|---|
| Average air qualityUS AQI, all measured cities. | 82 | 42 (better) |
| At ground stationsCities with a current station reading. | 82 | 43 (better) |
| Cities over AQI 100Not fine for sensitive groups. | 14% | 1% (better) |
| Forest lost since 2001The whole country. | 436,000 ha (better) | 126 million acres (51 million ha) |
| Share of its forest lostOf what it had in 2000. | 8.2% (better) | 18% |
| Average tree coverAcross its measured cities. | 28.4% (better) | 25.1% |
Air quality today
Is United States cleaner than South Korea?
On air quality, yes, right now. United States has cleaner air than South Korea right now: its cities average AQI 42 against 82.
At ground stations alone, which measure rather than estimate, the averages are South Korea 82 (56 cities) and United States 43 (279 cities).
14% of the measured cities in South Korea are over AQI 100 today, the point where the air stops being fine for sensitive groups, against 1% in the United States.
How each country's cities split across the air quality bands
South Korea
- Good2 (4%)
- Moderate46 (82%)
- Unhealthy for sensitive groups7 (13%)
- Unhealthy1 (2%)
United States
- Good178 (58%)
- Moderate127 (41%)
- Unhealthy for sensitive groups3 (1%)
Every measured city, including model estimates where no ground station is near.
Against everywhere else
How do South Korea and United States compare with other countries?
Right now the cities of South Korea average cleaner air than 11% of the 171 countries Airleaf has enough cities to average, and those of the United States than 66%.
Cleaner air than…
- South Korea
- Beats 11%
- United States
- Beats 66%
More tree cover than…
- South Korea
- Beats 64%
- United States
- Beats 52%
Deforestation · 2001–2025
Which country has lost more forest, South Korea or United States?
United States has lost more: about 126 million acres (51 million ha) of forest from 2001 to 2025, against 436,000 ha in South Korea, or 117 times as much. 9.87 million acres (4 million ha) of United States's was cleared for good, for farms, mines or towns; the rest burned, was logged or can grow back.
The whole country, from the yearly satellite maps of forest loss: unlike the city averages above, this counts every forest, not just the land around cities.
Worst year: 2025, with 87,000 ha lost.
Worst year: 2004, with 6.77 million acres (2.74 million ha) lost.
| South Korea | United States | |
|---|---|---|
| Forest lost since 2001Cleared, burned or logged. | 436,000 ha (better) | 126 million acres (51 million ha) |
| Share of its forestOf what it had in 2000. | 8.2% (better) | 18% |
| Cleared for goodTurned into farms, mines or towns. | 67,300 ha (better) | 9.87 million acres (4 million ha) |
| Recent trend2021–2025 against the five years before. | Speeding up | Holding steady |
| Main known cause | Logging (70%) | Logging (62%) |
Trees
Which country has more tree cover, South Korea or United States?
South Korea does: its measured cities average 28.4% tree cover against 25.1%, a gap of 3.3 percentage points.
| South Korea | United States | |
|---|---|---|
| Trees standingSummed across measured cities. | 4.8M | 23.3M (better) |
| Cities below their targetShort of the canopy target. | 57% (better) | 64% |
| Trees still neededTo reach those targets. | 1.3M (better) | 8.2M |
Behind the averages
The cities behind South Korea and United States
An average says nothing about how far apart the best and worst places are. These are the measured cities at each end.
South Korea
- Greenest measured city
- Geoje79.4% tree cover
- Worst air right now
- Cheongju-siAQI 154
United States
- Greenest measured city
- South Fulton71.7% tree cover
- Worst air right now
- East HamptonAQI 117
Reading these numbers
What a country average is, and is not
It is a mean of cities
Not a national statistic. Each figure is the average across the cities Airleaf has measured: 56 in South Korea and 308 in the United States, each read over the same 2 km radius, on the US EPA index. Rural land and unmeasured towns are not in it.
Coverage shapes the number
A country measured mostly in its capital reads differently from one measured across dozens of towns. United States rests on 308 cities against 56, so its average is the steadier of the two. Forest figures come from the University of Maryland's Global Forest Change maps.
Frequently asked
South Korea vs United States: your questions answered
Is United States cleaner than South Korea?
On air quality, yes, right now: United States's cities average AQI 42 against 82 on the US EPA index. These are live readings averaged across cities, so the gap moves with the weather. At ground stations alone, which measure rather than estimate, the averages are South Korea 82 (56 cities) and United States 43 (279 cities).
Which country has lost more forest, South Korea or United States?
United States has lost more: about 126 million acres (51 million ha) of forest from 2001 to 2025, against 436,000 ha in South Korea, or 117 times as much. 9.87 million acres (4 million ha) of United States's was cleared for good, for farms, mines or towns; the rest burned, was logged or can grow back.
Which country has more tree cover, South Korea or United States?
South Korea does: its measured cities average 28.4% tree cover against 25.1%, a gap of 3.3 percentage points.
How many cities are the South Korea and United States figures based on?
56 measured cities in South Korea and 308 in the United States. Every one was read the same way, so the two averages are directly comparable, but a country with more measured cities has the more settled figure.
Why are there two air quality averages for each country?
The first covers every measured city, using a ground station where one is close and a model estimate everywhere else. The second counts only cities with a current station reading, which is measured rather than estimated but covers fewer places. Airleaf's world rankings use the station figures only.
Does this cover the whole of South Korea and the United States?
The air and tree figures are not: they are the cities Airleaf has measured, each over the same 2 km radius, so treat them as a comparison of urban air and urban tree cover. The forest figures are: they count every forest in the country.
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