Air quality comparison · Malaysia, 18 km apart
Petaling Jaya vs Selayang Baru Utara Air quality index (AQI) today
Petaling Jaya has cleaner air than Selayang Baru Utara right now: AQI 66 (Moderate) against 113 (Unhealthy for sensitive groups).
That puts them in different EPA bands, so the health advice differs today. Over the past 7 days, on modeled daily averages, Petaling Jaya averaged AQI 87 against 92, and it was the cleaner of the two on 2 of those days. Selayang Baru Utara has lost more forest since 2001. Selayang Baru Utara has more tree cover.
Malaysia
AQI 66
Moderate
Cleaner right now
- PM2.5
- 17.3 µg/m³1.2× WHO guideline
- Main pollutant
- PM2.5
- Source
- Ground station
- Reading
- Nov 12, 00:00 local
Malaysia
AQI 113
Unhealthy for sensitive groups
Cleaner right now
- PM2.5
- 40.4 µg/m³2.7× WHO guideline
- Main pollutant
- PM2.5
- Source
- Ground station
- Reading
- Nov 11, 23:00 local
Updated . Lower is better on the US EPA index: 0–50 is Good, above 300 is Hazardous. Measured by Airleaf.
Petaling Jaya66Selayang Baru Utara113
Head to head
Petaling Jaya vs Selayang Baru Utara at a glance
Petaling Jaya is ahead on 4 of 6 measures, and Selayang Baru Utara on 2. The better figure in each row is marked.
| Petaling Jaya | Selayang Baru Utara | |
|---|---|---|
| Air quality nowUS AQI. Lower is better. | 66 (better) | 113 |
| PM2.5Fine particles, µg/m³. | 17.3 (better) | 40.4 |
| Past week's averageUS AQI, 7 days. | 87 (better) | 92 |
| Forest lost since 2001Within 10 km of the center. | 1,710 ha (better) | 2,370 ha |
| Tree coverWithin 2 km of the center. | 15.5% | 29.1% (better) |
| Trees still neededTo reach a healthy canopy. | 45.1K | 18.5K (better) |
Air quality today
What is the air like in Petaling Jaya and Selayang Baru Utara right now?
Petaling Jaya has cleaner air than Selayang Baru Utara right now: AQI 66 (Moderate) against 113 (Unhealthy for sensitive groups). PM2.5 is setting the index in both.
Petaling Jaya's PM2.5 is about 1.2× the WHO's 24-hour guideline of 15 µg/m³. Selayang Baru Utara's PM2.5 is about 2.7× the WHO's 24-hour guideline of 15 µg/m³.
Both readings come from nearby ground stations.
Petaling JayaSelayang Baru Utara
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).
Petaling Jaya: Ground station · Petaling Jaya, Selangor, Malaysia, 2.9 km away · median of 3 stations. Data: World Air Quality Index Project, Malaysia Department of Environment (DOE); Air Polluant Index Management System.
Selayang Baru Utara: Ground station · Batu Muda,Kuala Lumpur, Wilayah Persekutuan, Malaysia, 5 km away. Data: World Air Quality Index Project, Malaysia Department of Environment (DOE); Air Polluant Index Management System.
The past week
Which had cleaner air over the past 7 days?
Over the past 7 days, on modeled daily averages, Petaling Jaya averaged AQI 87 against 92, and it was the cleaner of the two on 2 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
- Petaling Jaya2Selayang Baru Utara0
- Average AQI
- Petaling Jaya87Selayang Baru Utara92
- Worst day, AQI
- Petaling Jaya93Selayang Baru Utara114
The daily numbers (7 days)
| Day | Petaling Jaya | Selayang Baru Utara |
|---|---|---|
| Nov 5 | 92 | 92 |
| Nov 6 | 90 | 90 |
| Nov 7 | 83 | 83 |
| Nov 8 | 87 | 87 |
| Nov 9 | 83 | 83 |
| Nov 10 | 93 | 94 |
| Nov 11 | 81 | 114 |
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 Petaling Jaya and Selayang Baru Utara today?
Petaling Jaya (AQI 66, Moderate): Unusually sensitive people should consider limiting long outdoor exertion.
Selayang Baru Utara (AQI 113, Unhealthy for sensitive groups): Sensitive groups should limit long or intense outdoor activity.
Exercise outdoors
- Petaling Jaya
- Fine for most people; unusually sensitive people should take long or hard exercise easier.
- Selayang Baru Utara
- Children, older adults and people with asthma or heart disease should cut down long or hard exercise.
Windows
- Petaling Jaya
- Fine to open; close them if you are sensitive to pollution.
- Selayang Baru Utara
- Close them to keep the outside air out.
Masks
- Petaling Jaya
- Not needed for most people.
- Selayang Baru Utara
- Sensitive groups: an N95 outdoors.
Air purifier
- Petaling Jaya
- Worth running if you are sensitive.
- Selayang Baru Utara
- Run one, especially in bedrooms.
Against everywhere else
How do Petaling Jaya and Selayang Baru Utara compare with the rest of the world?
Right now Petaling Jaya's air is cleaner than 41% of the 5,420 places Airleaf tracks, and Selayang Baru Utara's is cleaner than 18%. Within Malaysia, that is 33% and 0% of its 56 measured places.
Cleaner air than…
- Petaling Jaya
- Beats 41%
- Selayang Baru Utara
- Beats 18%
More tree cover than…
- Petaling Jaya
- Beats 36%
- Selayang Baru Utara
- Beats 67%
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, Petaling Jaya or Selayang Baru Utara?
Selayang Baru Utara has lost more: about 2,370 ha of forest within 10 km of its center from 2001 to 2025, against 1,710 ha around Petaling Jaya. 2,200 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: 2004, with 170 ha lost.
Worst year: 2004, with 175 ha lost.
| Petaling Jaya | Selayang Baru Utara | |
|---|---|---|
| Forest lost since 2001Cleared, burned or logged. | 1,710 ha (better) | 2,370 ha |
| Share of its forestOf what it had in 2000. | 31% | 13% (better) |
| Cleared for goodTurned into farms, mines or towns. | 1,710 ha (better) | 2,200 ha |
| Recent trend2021–2025 against the five years before. | Slowing down | Holding steady |
| Main known cause | Towns and roads (98%) | Towns and roads (57%) |
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.
Petaling Jaya
2017: satellite photo from February 2017 of a 5 × 5 km area about 7 km northwest of the city center.
Selayang Baru Utara
2017: satellite photo from February 2017 of a 5 × 5 km area about 7 km east of the city center.
Trees
Which has more trees, Petaling Jaya or Selayang Baru Utara?
Selayang Baru Utara has more tree cover: 29.1% of the land within 2 km of its center against 15.5% around Petaling Jaya, or about 91,146 trees against 48,159.
The dark mark is each place's canopy target: 30% of the land, raised where air quality is poor.
| Petaling Jaya | Selayang Baru Utara | |
|---|---|---|
| Trees standingEstimated from the canopy area. | 48.2K | 91.1K (better) |
| Trees still neededTo reach the target. Fewer is better. | 45.1K | 18.5K (better) |
| CO₂ absorbed each yearBy the trees already standing. | 1.1M kg | 2.0M 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
Petaling Jaya vs Selayang Baru Utara: your questions answered
Is Petaling Jaya cleaner than Selayang Baru Utara?
On air quality, yes, right now: Petaling Jaya reads AQI 66 against 113, a gap of 47 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, Petaling Jaya averaged AQI 87 against 92, and it was the cleaner of the two on 2 of those days.
Is it safe to exercise outdoors in Petaling Jaya and Selayang Baru Utara today?
In Petaling Jaya, at AQI 66: Unusually sensitive people should consider limiting long outdoor exertion. In Selayang Baru Utara, at AQI 113: Sensitive groups should limit long or intense outdoor activity.
Which has lost more forest, Petaling Jaya or Selayang Baru Utara?
Selayang Baru Utara has lost more: about 2,370 ha of forest within 10 km of its center from 2001 to 2025, against 1,710 ha around Petaling Jaya. 2,200 ha of that was cleared for good, for farms, mines or towns.
Which has more trees, Petaling Jaya or Selayang Baru Utara?
Selayang Baru Utara has more tree cover: 29.1% of the land within 2 km of its center against 15.5% around Petaling Jaya, or about 91,146 trees against 48,159. Both figures describe the same-sized circle of ground around each center, not the whole municipality.
How many more trees do Petaling Jaya and Selayang Baru Utara need?
Petaling Jaya needs about 45,052 more to reach its canopy target of 30%, and Selayang Baru Utara about 18,480 to reach 35%. The target starts at 30% of the land and rises where air quality is poor.
Why can two places 18 km apart read differently?
Air changes over short distances with traffic, industry, wind and hills, and each reading comes from the nearest ground stations or, where there are none, from a regional model. A gap of a few points between neighbors is within normal variation, while a gap that crosses an EPA band is worth noticing.
Are Petaling Jaya and Selayang Baru Utara 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 Petaling Jaya vs Selayang Baru Utara 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 15, 2026 and Aug 15, 2026), and the forest figures are published yearly.
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