Air quality comparison · Finland, 539 km apart
Helsinki vs Oulu Air quality index (AQI) today
Oulu has cleaner air than Helsinki right now: AQI 26 (Good) against 78 (Moderate).
That puts them in different EPA bands, so the health advice differs today. Over the past 6 days, on modeled daily averages, Oulu averaged AQI 9 against 15, and it was the cleaner of the two on 6 of those days. Oulu has lost more forest since 2001. Oulu has more tree cover.
Updated . Lower is better on the US EPA index: 0–50 is Good, above 300 is Hazardous. Measured by Airleaf.
Helsinki78Oulu26
Head to head
Helsinki vs Oulu at a glance
Oulu is ahead on 5 of 6 measures, and Helsinki on 1. The better figure in each row is marked.
| Helsinki | Oulu | |
|---|---|---|
| Air quality nowUS AQI. Lower is better. | 78 | 26 (better) |
| PM2.5Fine particles, µg/m³. | 23.5 | 4.6 (better) |
| Past week's averageUS AQI, 6 days. | 15 | 9 (better) |
| Forest lost since 2001Within 10 km of the center. | 500 ha (better) | 3,500 ha |
| Tree coverWithin 2 km of the center. | 25.3% | 37.5% (better) |
| Trees still neededTo reach a healthy canopy. | 11.7K | 0 (better) |
Air quality today
What is the air like in Helsinki and Oulu right now?
Oulu has cleaner air than Helsinki right now: AQI 26 (Good) against 78 (Moderate). PM2.5 is setting the index in both.
Helsinki's PM2.5 is about 1.6× the WHO's 24-hour guideline of 15 µg/m³.
Both readings come from nearby ground stations.
HelsinkiOulu
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 6 days?
Over the past 6 days, on modeled daily averages, Oulu averaged AQI 9 against 15, and it was the cleaner of the two on 6 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
- Helsinki0Oulu6
- Average AQI
- Helsinki15Oulu9
- Worst day, AQI
- Helsinki25Oulu11
The daily numbers (6 days)
| Day | Helsinki | Oulu |
|---|---|---|
| Nov 5 | 10 | 9 |
| Nov 6 | 13 | 8 |
| Nov 7 | 15 | 8 |
| Nov 8 | 13 | 9 |
| Nov 9 | 16 | 8 |
| Nov 10 | 25 | 11 |
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 Helsinki and Oulu today?
Helsinki (AQI 78, Moderate): Unusually sensitive people should consider limiting long outdoor exertion.
Oulu (AQI 26, Good): Air quality is satisfactory for everyone.
Exercise outdoors
- Helsinki
- Fine for most people; unusually sensitive people should take long or hard exercise easier.
- Oulu
- A good day to be active outside.
Windows
- Helsinki
- Fine to open; close them if you are sensitive to pollution.
- Oulu
- Open them to air the house.
Masks
- Helsinki
- Not needed for most people.
- Oulu
- Not needed.
Air purifier
- Helsinki
- Worth running if you are sensitive.
- Oulu
- Not needed.
Against everywhere else
How do Helsinki and Oulu compare with the rest of the world?
Right now Helsinki's air is cleaner than 31% of the 5,420 places Airleaf tracks, and Oulu's is cleaner than 84%. Within Finland, that is 13% and 75% of its 9 measured places.
Cleaner air than…
- Helsinki
- Beats 31%
- Oulu
- Beats 84%
More tree cover than…
- Helsinki
- Beats 58%
- Oulu
- Beats 80%
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, Helsinki or Oulu?
Oulu has lost more: about 3,500 ha of forest within 10 km of its center from 2001 to 2025, against 500 ha around Helsinki. 2,230 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: 2006, with 51 ha lost.
Worst year: 2017, with 371 ha lost.
| Helsinki | Oulu | |
|---|---|---|
| Forest lost since 2001Cleared, burned or logged. | 500 ha (better) | 3,500 ha |
| Share of its forestOf what it had in 2000. | 7.8% (better) | 25% |
| Cleared for goodTurned into farms, mines or towns. | 473 ha (better) | 2,230 ha |
| Recent trend2021–2025 against the five years before. | Too little to call | Slowing down |
| Main known cause | Towns and roads (94%) | Towns and roads (60%) |
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.
Helsinki
2017: satellite photo from August 2017 of a 5 × 5 km area about 7 km north of the city center.
Oulu
2017: satellite photo from September 2017 of a 5 × 5 km area about 7 km east of the city center.
Trees
Which has more trees, Helsinki or Oulu?
Oulu has more tree cover: 37.5% of the land within 2 km of its center against 25.3% around Helsinki, or about 102,377 trees against 62,870.
The dark mark is each place's canopy target: 30% of the land, raised where air quality is poor.
| Helsinki | Oulu | |
|---|---|---|
| Trees standingEstimated from the canopy area. | 62.9K | 102K (better) |
| Trees still neededTo reach the target. Fewer is better. | 11.7K | 0 (better) |
| CO₂ absorbed each yearBy the trees already standing. | 1.4M kg | 2.3M 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
Helsinki vs Oulu: your questions answered
Is Oulu cleaner than Helsinki?
On air quality, yes, right now: Oulu reads AQI 26 against 78, a gap of 52 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 6 days, on modeled daily averages, Oulu averaged AQI 9 against 15, and it was the cleaner of the two on 6 of those days.
Is it safe to exercise outdoors in Helsinki and Oulu today?
In Helsinki, at AQI 78: Unusually sensitive people should consider limiting long outdoor exertion. In Oulu, at AQI 26: Air quality is satisfactory for everyone.
Which has lost more forest, Helsinki or Oulu?
Oulu has lost more: about 3,500 ha of forest within 10 km of its center from 2001 to 2025, against 500 ha around Helsinki. 2,230 ha of that was cleared for good, for farms, mines or towns.
Which has more trees, Helsinki or Oulu?
Oulu has more tree cover: 37.5% of the land within 2 km of its center against 25.3% around Helsinki, or about 102,377 trees against 62,870. Both figures describe the same-sized circle of ground around each center, not the whole municipality.
How many more trees do Helsinki and Oulu need?
Helsinki needs about 11,679 more to reach its canopy target of 30%, and Oulu about 0 to reach 30%. The target starts at 30% of the land and rises where air quality is poor.
Are Helsinki and Oulu 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 Helsinki vs Oulu 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 (Sep 3, 2026 and Sep 11, 2026), and the forest figures are published yearly.
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