Air quality comparison · Puerto Rico, 46.6 mi (75 km) apart
Ponce vs San Juan Air quality index (AQI) today
San Juan has cleaner air than Ponce right now: AQI 60 (Moderate) against 63 (Moderate).
Both sit in the same EPA band, so the health advice is the same for each today. But over the past 7 days, on modeled daily averages, Ponce averaged AQI 27 against 31, and it was the cleaner of the two on 5 of those days. Ponce has lost more forest since 2001. Ponce has more tree cover.
Updated . Lower is better on the US EPA index: 0–50 is Good, above 300 is Hazardous. Measured by Airleaf.
Ponce63San Juan60
Head to head
Ponce vs San Juan at a glance
Ponce and San Juan are level, each ahead on 3 of 6 measures. The better figure in each row is marked.
| Ponce | San Juan | |
|---|---|---|
| Air quality nowUS AQI. Lower is better. | 63 | 60 (better) |
| PM2.5Fine particles, µg/m³. | 17.6 | 14 (better) |
| Past week's averageUS AQI, 7 days. | 27 (better) | 31 |
| Forest lost since 2001Within 10 km of the center. | 2,420 acres (978 ha) | 596 acres (241 ha) (better) |
| Tree coverWithin 1.2 mi (2 km) of the center. | 26.5% (better) | 8.6% |
| Trees still neededTo reach a healthy canopy. | 11.0K (better) | 19.2K |
Air quality today
What is the air like in Ponce and San Juan right now?
San Juan has cleaner air than Ponce right now: AQI 60 (Moderate) against 63 (Moderate). PM2.5 is setting the index in both.
Ponce's PM2.5 is about 1.2× the WHO's 24-hour guideline of 15 µg/m³.
San Juan is read from a nearby ground station and Ponce is a model estimate, so the two are not quite like for like.
PonceSan Juan
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).
Ponce: Estimate · model corrected with 4 station cities within 52.8 mi (85 km), e.g. Bayamón and Caguas. Data: Open-Meteo / CAMS, corrected with 4 ground-station cities within 85 km, US EPA index.
San Juan: Ground station · Cataño 40, 3.5 mi (5.7 km) away. Data: OpenAQ · AirNow.
The past week
Which had cleaner air over the past 7 days?
But over the past 7 days, on modeled daily averages, Ponce averaged AQI 27 against 31, and it was the cleaner of the two on 5 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
- Ponce5San Juan0
- Average AQI
- Ponce27San Juan31
- Worst day, AQI
- Ponce54San Juan55
The daily numbers (7 days)
| Day | Ponce | San Juan |
|---|---|---|
| Nov 4 | 52 | 55 |
| Nov 5 | 54 | 54 |
| Nov 6 | 27 | 40 |
| Nov 7 | 10 | 12 |
| Nov 8 | 14 | 22 |
| Nov 9 | 17 | 18 |
| Nov 10 | 18 | 18 |
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 Ponce and San Juan today?
Unusually sensitive people should consider limiting long outdoor exertion. Both are in the same EPA band today (Moderate), so the advice is the same.
Exercise outdoors
Fine for most people; unusually sensitive people should take long or hard exercise easier.
Windows
Fine to open; close them if you are sensitive to pollution.
Masks
Not needed for most people.
Air purifier
Worth running if you are sensitive.
Against everywhere else
How do Ponce and San Juan compare with the rest of the world?
Right now Ponce's air is cleaner than 45% of the 5,420 places Airleaf tracks, and San Juan's is cleaner than 48%. Within Puerto Rico, that is 17% and 33% of its 7 measured places.
Cleaner air than…
- Ponce
- Beats 45%
- San Juan
- Beats 48%
More tree cover than…
- Ponce
- Beats 61%
- San Juan
- Beats 18%
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, Ponce or San Juan?
Ponce has lost more: about 2,420 acres (978 ha) of forest within 10 km of its center from 2001 to 2025, against 596 acres (241 ha) around San Juan. 1,810 acres (733 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: 2017, with 472 acres (191 ha) lost.
Worst year: 2017, with 437 acres (177 ha) lost.
| Ponce | San Juan | |
|---|---|---|
| Forest lost since 2001Cleared, burned or logged. | 2,420 acres (978 ha) | 596 acres (241 ha) (better) |
| Share of its forestOf what it had in 2000. | 8.3% (better) | 17% |
| Cleared for goodTurned into farms, mines or towns. | 1,810 acres (733 ha) | 201 acres (81 ha) (better) |
| Recent trend2021–2025 against the five years before. | Slowing down | Too little to call |
| Main known cause | Farms, pasture and plantations (31%) | Storms, floods and other natural causes (64%) |
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.
Ponce
2017: satellite photo from January 2017 of a 5 × 5 km area about 7 km north of the city center.
San Juan
2017: satellite photo from February 2017 of a 5 × 5 km area about 7 km southeast of the city center.
Trees
Which has more trees, Ponce or San Juan?
Ponce has more tree cover: 26.5% of the land within 1.2 mi (2 km) of its center against 8.6% around San Juan, or about 83,252 trees against 7,727.
The dark mark is each place's canopy target: 30% of the land, raised where air quality is poor.
| Ponce | San Juan | |
|---|---|---|
| Trees standingEstimated from the canopy area. | 83.3K (better) | 7.7K |
| Trees still neededTo reach the target. Fewer is better. | 11.0K (better) | 19.2K |
| CO₂ absorbed each yearBy the trees already standing. | 1.8M kg (better) | 170K kg |
Tree cover on the satellite image
The same 1.2 mi (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 1.2 mi (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
Ponce vs San Juan: your questions answered
Is San Juan cleaner than Ponce?
On air quality, yes, right now: San Juan reads AQI 60 against 63, a gap of 3 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, Ponce averaged AQI 27 against 31, and it was the cleaner of the two on 5 of those days.
Is it safe to exercise outdoors in Ponce and San Juan today?
The advice is the same for both today. Unusually sensitive people should consider limiting long outdoor exertion. Ponce reads AQI 63 and San Juan reads AQI 60.
Which has lost more forest, Ponce or San Juan?
Ponce has lost more: about 2,420 acres (978 ha) of forest within 10 km of its center from 2001 to 2025, against 596 acres (241 ha) around San Juan. 1,810 acres (733 ha) of that was cleared for good, for farms, mines or towns.
Which has more trees, Ponce or San Juan?
Ponce has more tree cover: 26.5% of the land within 1.2 mi (2 km) of its center against 8.6% around San Juan, or about 83,252 trees against 7,727. Both figures describe the same-sized circle of ground around each center, not the whole municipality.
How many more trees do Ponce and San Juan need?
Ponce needs about 10,996 more to reach its canopy target of 30%, and San Juan about 19,228 to reach 30%. The target starts at 30% of the land and rises where air quality is poor.
Are Ponce and San Juan 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 Juan is read from a nearby ground station and Ponce 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 Ponce vs San Juan 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 8, 2026 and Sep 18, 2026), and the forest figures are published yearly.
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