Air quality comparison · Costa Rica, 167 km apart
Liberia vs San José Air quality index (AQI) today
Liberia has cleaner air than San José right now: AQI 11 (Good) against 40 (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, Liberia averaged AQI 13 against 44, and it was the cleaner of the two on 7 of those days. San José has lost more forest since 2001. Liberia has more tree cover.
Updated . Lower is better on the US EPA index: 0–50 is Good, above 300 is Hazardous. Measured by Airleaf.
Liberia11San José40
Head to head
Liberia vs San José at a glance
Liberia is ahead on 6 of 6 measures, and San José on 0. The better figure in each row is marked.
| Liberia | San José | |
|---|---|---|
| Air quality nowUS AQI. Lower is better. | 11 (better) | 40 |
| PM2.5Fine particles, µg/m³. | 2 (better) | 7.2 |
| Past week's averageUS AQI, 7 days. | 13 (better) | 44 |
| Forest lost since 2001Within 10 km of the center. | 993 ha (better) | 1,510 ha |
| Tree coverWithin 2 km of the center. | 34.6% (better) | 13.4% |
| Trees still neededTo reach a healthy canopy. | 0 (better) | 52.1K |
Air quality today
What is the air like in Liberia and San José right now?
Liberia has cleaner air than San José right now: AQI 11 (Good) against 40 (Good). PM2.5 is setting the index in both.
San José is read from a nearby ground station and Liberia is a model estimate, so the two are not quite like for like.
LiberiaSan José
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).
Liberia: Estimate · model corrected with 4 station cities within 205 km, e.g. Masaya and San José. Data: Open-Meteo / CAMS, corrected with 4 ground-station cities within 205 km, US EPA index.
San José: Ground station · NASA GSFC Rutgers Calib. N13, 4.8 km away. Data: OpenAQ · Clarity.
The past week
Which had cleaner air over the past 7 days?
Over the past 7 days, on modeled daily averages, Liberia averaged AQI 13 against 44, and it was the cleaner of the two on 7 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
- Liberia7San José0
- Average AQI
- Liberia13San José44
- Worst day, AQI
- Liberia17San José52
The daily numbers (7 days)
| Day | Liberia | San José |
|---|---|---|
| Nov 4 | 17 | 51 |
| Nov 5 | 16 | 52 |
| Nov 6 | 8 | 47 |
| Nov 7 | 6 | 42 |
| Nov 8 | 12 | 35 |
| Nov 9 | 17 | 42 |
| Nov 10 | 15 | 36 |
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 Liberia and San José 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 Liberia and San José compare with the rest of the world?
Right now Liberia's air is cleaner than 95% of the 5,420 places Airleaf tracks, and San José's is cleaner than 70%. Within Costa Rica, that is 100% and 0% of its 5 measured places.
Cleaner air than…
- Liberia
- Beats 95%
- San José
- Beats 70%
More tree cover than…
- Liberia
- Beats 77%
- San José
- Beats 30%
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, Liberia or San José?
San José has lost more: about 1,510 ha of forest within 10 km of its center from 2001 to 2025, against 993 ha around Liberia. 1,480 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: 2005, with 134 ha lost.
Worst year: 2002, with 355 ha lost.
| Liberia | San José | |
|---|---|---|
| Forest lost since 2001Cleared, burned or logged. | 993 ha (better) | 1,510 ha |
| Share of its forestOf what it had in 2000. | 8.4% (better) | 13% |
| Cleared for goodTurned into farms, mines or towns. | 975 ha (better) | 1,480 ha |
| Recent trend2021–2025 against the five years before. | Too little to call | Too little to call |
| Main known cause | Farms, pasture and plantations (94%) | Towns and roads (70%) |
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.
Liberia
2017: satellite photo from February 2017 of a 5 × 5 km area about 4 km southwest of the city center.
San José
2017: satellite photo from March 2017 of a 5 × 5 km area about 7 km north of the city center.
Trees
Which has more trees, Liberia or San José?
Liberia has more tree cover: 34.6% of the land within 2 km of its center against 13.4% around San José, or about 108,699 trees against 42,097.
The dark mark is each place's canopy target: 30% of the land, raised where air quality is poor.
| Liberia | San José | |
|---|---|---|
| Trees standingEstimated from the canopy area. | 109K (better) | 42.1K |
| Trees still neededTo reach the target. Fewer is better. | 0 (better) | 52.1K |
| CO₂ absorbed each yearBy the trees already standing. | 2.4M kg (better) | 926K 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
Liberia vs San José: your questions answered
Is Liberia cleaner than San José?
On air quality, yes, right now: Liberia reads AQI 11 against 40, a gap of 29 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, Liberia averaged AQI 13 against 44, and it was the cleaner of the two on 7 of those days.
Is it safe to exercise outdoors in Liberia and San José today?
The advice is the same for both today. Air quality is satisfactory for everyone. Liberia reads AQI 11 and San José reads AQI 40.
Which has lost more forest, Liberia or San José?
San José has lost more: about 1,510 ha of forest within 10 km of its center from 2001 to 2025, against 993 ha around Liberia. 1,480 ha of that was cleared for good, for farms, mines or towns.
Which has more trees, Liberia or San José?
Liberia has more tree cover: 34.6% of the land within 2 km of its center against 13.4% around San José, or about 108,699 trees against 42,097. Both figures describe the same-sized circle of ground around each center, not the whole municipality.
How many more trees do Liberia and San José need?
Liberia needs about 0 more to reach its canopy target of 30%, and San José about 52,150 to reach 30%. The target starts at 30% of the land and rises where air quality is poor.
Are Liberia and San José 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. San José is read from a nearby ground station and Liberia 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 Liberia vs San José 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 22, 2026 and Jun 28, 2026), and the forest figures are published yearly.
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