Air quality comparison · Germany, 357 km apart
Hamburg vs Köln Air quality index (AQI) today
Köln has cleaner air than Hamburg right now: AQI 47 (Good) against 69 (Moderate).
That puts them in different EPA bands, so the health advice differs today. But over the past 7 days, on modeled daily averages, Hamburg averaged AQI 64 against 68, and it was the cleaner of the two on 4 of those days. Köln has lost more forest since 2001. Köln has more tree cover.
Updated . Lower is better on the US EPA index: 0–50 is Good, above 300 is Hazardous. Measured by Airleaf.
Hamburg69Köln47
Head to head
Hamburg vs Köln at a glance
Köln is ahead on 4 of 6 measures, and Hamburg on 2. The better figure in each row is marked.
| Hamburg | Köln | |
|---|---|---|
| Air quality nowUS AQI. Lower is better. | 69 | 47 (better) |
| PM2.5Fine particles, µg/m³. | 18.6 | 8.4 (better) |
| Past week's averageUS AQI, 7 days. | 64 (better) | 68 |
| Forest lost since 2001Within 10 km of the center. | 67 ha (better) | 83 ha |
| Tree coverWithin 2 km of the center. | 21.2% | 27.1% (better) |
| Trees still neededTo reach a healthy canopy. | 21.5K | 8.3K (better) |
Air quality today
What is the air like in Hamburg and Köln right now?
Köln has cleaner air than Hamburg right now: AQI 47 (Good) against 69 (Moderate). PM2.5 is setting the index in both.
Hamburg's PM2.5 is about 1.2× the WHO's 24-hour guideline of 15 µg/m³.
Both readings come from nearby ground stations.
HamburgKöln
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).
The past week
Which had cleaner air over the past 7 days?
But over the past 7 days, on modeled daily averages, Hamburg averaged AQI 64 against 68, and it was the cleaner of the two on 4 of those days. A single reading can catch a city on a bad afternoon; the week says whether it was the weather or the place.
- Cleaner days
- Hamburg4Köln3
- Average AQI
- Hamburg64Köln68
- Worst day, AQI
- Hamburg87Köln82
The daily numbers (7 days)
| Day | Hamburg | Köln |
|---|---|---|
| Nov 4 | 36 | 43 |
| Nov 5 | 43 | 53 |
| Nov 6 | 54 | 67 |
| Nov 7 | 58 | 82 |
| Nov 8 | 87 | 76 |
| Nov 9 | 85 | 81 |
| Nov 10 | 83 | 73 |
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 Hamburg and Köln today?
Hamburg (AQI 69, Moderate): Unusually sensitive people should consider limiting long outdoor exertion.
Köln (AQI 47, Good): Air quality is satisfactory for everyone.
Exercise outdoors
- Hamburg
- Fine for most people; unusually sensitive people should take long or hard exercise easier.
- Köln
- A good day to be active outside.
Windows
- Hamburg
- Fine to open; close them if you are sensitive to pollution.
- Köln
- Open them to air the house.
Masks
- Hamburg
- Not needed for most people.
- Köln
- Not needed.
Air purifier
- Hamburg
- Worth running if you are sensitive.
- Köln
- Not needed.
Against everywhere else
How do Hamburg and Köln compare with the rest of the world?
Right now Hamburg's air is cleaner than 38% of the 5,420 places Airleaf tracks, and Köln's is cleaner than 64%. Within Germany, that is 41% and 89% of its 71 measured places.
Cleaner air than…
- Hamburg
- Beats 38%
- Köln
- Beats 64%
More tree cover than…
- Hamburg
- Beats 49%
- Köln
- Beats 62%
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, Hamburg or Köln?
Köln has lost more: about 83 ha of forest within 10 km of its center from 2001 to 2025, against 67 ha around Hamburg. 60 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: 2019, with 9 ha lost.
Worst year: 2010, with 7 ha lost.
| Hamburg | Köln | |
|---|---|---|
| Forest lost since 2001Cleared, burned or logged. | 67 ha (better) | 83 ha |
| Share of its forestOf what it had in 2000. | 1% (better) | 1.2% |
| Cleared for goodTurned into farms, mines or towns. | 51 ha (better) | 60 ha |
| Recent trend2021–2025 against the five years before. | Too little to call | Too little to call |
| Main known cause | Towns and roads (74%) | Towns and roads (72%) |
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.
Hamburg
2017: satellite photo from July 2017 of a 5 × 5 km area in the city center.
Köln
2017: satellite photo from August 2017 of a 5 × 5 km area in the city center.
Trees
Which has more trees, Hamburg or Köln?
Köln has more tree cover: 27.1% of the land within 2 km of its center against 21.2% around Hamburg, or about 77,815 trees against 51,683.
The dark mark is each place's canopy target: 30% of the land, raised where air quality is poor.
| Hamburg | Köln | |
|---|---|---|
| Trees standingEstimated from the canopy area. | 51.7K | 77.8K (better) |
| Trees still neededTo reach the target. Fewer is better. | 21.5K | 8.3K (better) |
| CO₂ absorbed each yearBy the trees already standing. | 1.1M kg | 1.7M kg (better) |
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
Hamburg vs Köln: your questions answered
Is Köln cleaner than Hamburg?
On air quality, yes, right now: Köln reads AQI 47 against 69, a gap of 22 points on the US EPA index. This is a live reading rather than an annual average, so it can reverse within a day. But over the past 7 days, on modeled daily averages, Hamburg averaged AQI 64 against 68, and it was the cleaner of the two on 4 of those days.
Is it safe to exercise outdoors in Hamburg and Köln today?
In Hamburg, at AQI 69: Unusually sensitive people should consider limiting long outdoor exertion. In Köln, at AQI 47: Air quality is satisfactory for everyone.
Which has lost more forest, Hamburg or Köln?
Köln has lost more: about 83 ha of forest within 10 km of its center from 2001 to 2025, against 67 ha around Hamburg. 60 ha of that was cleared for good, for farms, mines or towns.
Which has more trees, Hamburg or Köln?
Köln has more tree cover: 27.1% of the land within 2 km of its center against 21.2% around Hamburg, or about 77,815 trees against 51,683. Both figures describe the same-sized circle of ground around each center, not the whole municipality.
How many more trees do Hamburg and Köln need?
Hamburg needs about 21,453 more to reach its canopy target of 30%, and Köln about 8,327 to reach 30%. The target starts at 30% of the land and rises where air quality is poor.
Are Hamburg and Köln 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. Both readings come from nearby ground stations. Nothing is adjusted for population, city limits or climate.
How often does the Hamburg vs Köln 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 14, 2026 and Aug 16, 2026), and the forest figures are published yearly.
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