Air quality comparison · United States, 1217.9 mi (1960 km) apart
Houston vs Washington Air quality index (AQI) today
Houston has cleaner air than Washington right now: AQI 62 (Moderate) against 64 (Moderate).
Both sit in the same EPA band, so the health advice is the same for each today. But over the past 6 days, on modeled daily averages, Washington averaged AQI 35 against 78, and it was the cleaner of the two on 6 of those days. Houston has lost more forest since 2001. Washington has more tree cover.
United States
AQI 62
Moderate
Cleaner right now
- PM2.5
- 15.1 µg/m³1.0× WHO guideline
- Main pollutant
- PM2.5
- Source
- Ground station
- Reading
- Nov 11, 09:00 local
United States
AQI 64
Moderate
Cleaner right now
- PM2.5
- 16 µg/m³1.1× WHO guideline
- Main pollutant
- PM2.5
- Source
- Ground station
- Reading
- Nov 11, 10:00 local
Updated . Lower is better on the US EPA index: 0–50 is Good, above 300 is Hazardous. Measured by Airleaf.
Houston62Washington64
Head to head
Houston vs Washington at a glance
Washington is ahead on 4 of 6 measures, and Houston on 2. The better figure in each row is marked.
| Houston | Washington | |
|---|---|---|
| Air quality nowUS AQI. Lower is better. | 62 (better) | 64 |
| PM2.5Fine particles, µg/m³. | 15.1 (better) | 16 |
| Past week's averageUS AQI, 6 days. | 78 | 35 (better) |
| Forest lost since 2001Within 10 km of the center. | 566 acres (229 ha) | 291 acres (118 ha) (better) |
| Tree coverWithin 1.2 mi (2 km) of the center. | 15.6% | 18.6% (better) |
| Trees still neededTo reach a healthy canopy. | 44.9K | 30.5K (better) |
Air quality today
What is the air like in Houston and Washington right now?
Houston has cleaner air than Washington right now: AQI 62 (Moderate) against 64 (Moderate). PM2.5 is setting the index in both.
Houston's PM2.5 is about 1.0× the WHO's 24-hour guideline of 15 µg/m³. Washington's PM2.5 is about 1.1× the WHO's 24-hour guideline of 15 µg/m³.
Both readings come from nearby ground stations.
HoustonWashington
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?
But over the past 6 days, on modeled daily averages, Washington averaged AQI 35 against 78, 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
- Houston0Washington6
- Average AQI
- Houston78Washington35
- Worst day, AQI
- Houston97Washington60
The daily numbers (6 days)
| Day | Houston | Washington |
|---|---|---|
| Nov 5 | 97 | 35 |
| Nov 6 | 95 | 30 |
| Nov 7 | 77 | 27 |
| Nov 8 | 52 | 30 |
| Nov 9 | 69 | 27 |
| Nov 10 | 79 | 60 |
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 Houston and Washington 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 Houston and Washington compare with the rest of the world?
Right now Houston's air is cleaner than 46% of the 5,420 places Airleaf tracks, and Washington's is cleaner than 44%. Within United States, that is 20% and 17% of its 308 measured places.
Cleaner air than…
- Houston
- Beats 46%
- Washington
- Beats 44%
More tree cover than…
- Houston
- Beats 36%
- Washington
- Beats 43%
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, Houston or Washington?
Houston has lost more: about 566 acres (229 ha) of forest within 10 km of its center from 2001 to 2025, against 291 acres (118 ha) around Washington. 540 acres (219 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: 2011, with 180 acres (73 ha) lost.
Worst year: 2012, with 30 acres (12 ha) lost.
| Houston | Washington | |
|---|---|---|
| Forest lost since 2001Cleared, burned or logged. | 566 acres (229 ha) | 291 acres (118 ha) (better) |
| Share of its forestOf what it had in 2000. | 11% | 1.4% (better) |
| Cleared for goodTurned into farms, mines or towns. | 540 acres (219 ha) | 259 acres (105 ha) (better) |
| Recent trend2021–2025 against the five years before. | Too little to call | Too little to call |
| Main known cause | Towns and roads (95%) | Towns and roads (89%) |
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.
Houston
2018: satellite photo from November 2018 of a 5 × 5 km area in the city center.
Washington
2017: satellite photo from July 2017 of a 5 × 5 km area in the city center.
Trees
Which has more trees, Houston or Washington?
Washington has more tree cover: 18.6% of the land within 1.2 mi (2 km) of its center against 15.6% around Houston, or about 49,727 trees against 48,666.
The dark mark is each place's canopy target: 30% of the land, raised where air quality is poor.
| Houston | Washington | |
|---|---|---|
| Trees standingEstimated from the canopy area. | 48.7K | 49.7K (better) |
| Trees still neededTo reach the target. Fewer is better. | 44.9K | 30.5K (better) |
| CO₂ absorbed each yearBy the trees already standing. | 1.1M kg | 1.1M kg (better) |
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
Houston vs Washington: your questions answered
Is Houston cleaner than Washington?
On air quality, yes, right now: Houston reads AQI 62 against 64, a gap of 2 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 6 days, on modeled daily averages, Washington averaged AQI 35 against 78, and it was the cleaner of the two on 6 of those days.
Is it safe to exercise outdoors in Houston and Washington today?
The advice is the same for both today. Unusually sensitive people should consider limiting long outdoor exertion. Houston reads AQI 62 and Washington reads AQI 64.
Which has lost more forest, Houston or Washington?
Houston has lost more: about 566 acres (229 ha) of forest within 10 km of its center from 2001 to 2025, against 291 acres (118 ha) around Washington. 540 acres (219 ha) of that was cleared for good, for farms, mines or towns.
Which has more trees, Houston or Washington?
Washington has more tree cover: 18.6% of the land within 1.2 mi (2 km) of its center against 15.6% around Houston, or about 49,727 trees against 48,666. Both figures describe the same-sized circle of ground around each center, not the whole municipality.
How many more trees do Houston and Washington need?
Houston needs about 44,922 more to reach its canopy target of 30%, and Washington about 30,478 to reach 30%. The target starts at 30% of the land and rises where air quality is poor.
Are Houston and Washington 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 Houston vs Washington 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 (Oct 19, 2026 and Sep 9, 2026), and the forest figures are published yearly.
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