Air quality comparison · Taiwan, 137 km apart
Taichung vs Tainan Air quality index (AQI) today
Taichung has cleaner air than Tainan right now: AQI 68 (Moderate) against 77 (Moderate).
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, Taichung averaged AQI 100 against 103, and it was the cleaner of the two on 5 of those days. Taichung has lost more forest since 2001. Tainan has more tree cover.
Updated . Lower is better on the US EPA index: 0–50 is Good, above 300 is Hazardous. Measured by Airleaf.
Taichung68Tainan77
Head to head
Taichung vs Tainan at a glance
Taichung and Tainan are level, each ahead on 3 of 6 measures. The better figure in each row is marked.
| Taichung | Tainan | |
|---|---|---|
| Air quality nowUS AQI. Lower is better. | 68 (better) | 77 |
| PM2.5Fine particles, µg/m³. | 18 (better) | 23 |
| Past week's averageUS AQI, 7 days. | 100 (better) | 103 |
| Forest lost since 2001Within 10 km of the center. | 201 ha | 11 ha (better) |
| Tree coverWithin 2 km of the center. | 9.9% | 12.3% (better) |
| Trees still neededTo reach a healthy canopy. | 63.1K | 55.6K (better) |
Air quality today
What is the air like in Taichung and Tainan right now?
Taichung has cleaner air than Tainan right now: AQI 68 (Moderate) against 77 (Moderate). PM2.5 is setting the index in both.
Taichung's PM2.5 is about 1.2× the WHO's 24-hour guideline of 15 µg/m³. Tainan's PM2.5 is about 1.5× the WHO's 24-hour guideline of 15 µg/m³.
Both readings come from nearby ground stations.
TaichungTainan
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).
Taichung: Ground station · 臺中市 - 臺灣大道, 3.1 km away · median of 4 stations. Data: OpenAQ · Taiwan, Ministry of Environment, Taiwan (Open Government Data License 1.0).
Tainan: Ground station · 臺南市 - 林森, 1.1 km away · median of 3 stations. Data: OpenAQ · Taiwan, Ministry of Environment, Taiwan (Open Government Data License 1.0).
The past week
Which had cleaner air over the past 7 days?
Over the past 7 days, on modeled daily averages, Taichung averaged AQI 100 against 103, 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
- Taichung5Tainan2
- Average AQI
- Taichung100Tainan103
- Worst day, AQI
- Taichung131Tainan138
The daily numbers (7 days)
| Day | Taichung | Tainan |
|---|---|---|
| Nov 5 | 114 | 117 |
| Nov 6 | 131 | 138 |
| Nov 7 | 114 | 121 |
| Nov 8 | 109 | 95 |
| Nov 9 | 69 | 99 |
| Nov 10 | 66 | 70 |
| Nov 11 | 99 | 84 |
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 Taichung and Tainan 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 Taichung and Tainan compare with the rest of the world?
Right now Taichung's air is cleaner than 39% of the 5,420 places Airleaf tracks, and Tainan's is cleaner than 33%. Within Taiwan, that is 12% and 0% of its 18 measured places.
Cleaner air than…
- Taichung
- Beats 39%
- Tainan
- Beats 33%
More tree cover than…
- Taichung
- Beats 21%
- Tainan
- Beats 27%
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, Taichung or Tainan?
Taichung has lost more: about 201 ha of forest within 10 km of its center from 2001 to 2025, against 11 ha around Tainan. 197 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: 2012, with 28 ha lost.
Worst year: 2006, with 2 ha lost.
| Taichung | Tainan | |
|---|---|---|
| Forest lost since 2001Cleared, burned or logged. | 201 ha | 11 ha (better) |
| Share of its forestOf what it had in 2000. | 4% | 2.8% (better) |
| Cleared for goodTurned into farms, mines or towns. | 197 ha | 3 ha (better) |
| Recent trend2021–2025 against the five years before. | Too little to call | Too little to call |
| Main known cause | Towns and roads (58%) | Towns and roads (28%) |
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.
Taichung
2017: satellite photo from January 2017 of a 5 × 5 km area about 7 km east of the city center.
Tainan
2017: satellite photo from February 2017 of a 5 × 5 km area in the city center.
Trees
Which has more trees, Taichung or Tainan?
Tainan has more tree cover: 12.3% of the land within 2 km of its center against 9.9% around Taichung, or about 38,642 trees against 31,102.
The dark mark is each place's canopy target: 30% of the land, raised where air quality is poor.
| Taichung | Tainan | |
|---|---|---|
| Trees standingEstimated from the canopy area. | 31.1K | 38.6K (better) |
| Trees still neededTo reach the target. Fewer is better. | 63.1K | 55.6K (better) |
| CO₂ absorbed each yearBy the trees already standing. | 684K kg | 850K 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
Taichung vs Tainan: your questions answered
Is Taichung cleaner than Tainan?
On air quality, yes, right now: Taichung reads AQI 68 against 77, a gap of 9 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, Taichung averaged AQI 100 against 103, and it was the cleaner of the two on 5 of those days.
Is it safe to exercise outdoors in Taichung and Tainan today?
The advice is the same for both today. Unusually sensitive people should consider limiting long outdoor exertion. Taichung reads AQI 68 and Tainan reads AQI 77.
Which has lost more forest, Taichung or Tainan?
Taichung has lost more: about 201 ha of forest within 10 km of its center from 2001 to 2025, against 11 ha around Tainan. 197 ha of that was cleared for good, for farms, mines or towns.
Which has more trees, Taichung or Tainan?
Tainan has more tree cover: 12.3% of the land within 2 km of its center against 9.9% around Taichung, or about 38,642 trees against 31,102. Both figures describe the same-sized circle of ground around each center, not the whole municipality.
How many more trees do Taichung and Tainan need?
Taichung needs about 63,146 more to reach its canopy target of 30%, and Tainan about 55,606 to reach 30%. The target starts at 30% of the land and rises where air quality is poor.
Are Taichung and Tainan 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 Taichung vs Tainan 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 16, 2026 and Sep 18, 2026), and the forest figures are published yearly.
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