Worst air pollution Mountain Ash, today and tomorrow
Today (9 August): Air quality in Mountain Ash is poor. AQI and O3 are poor; PM2.5 and PM1 are fair; NO2 is medium; PM10, SO2, CO, and HCHO are good. Pollution peaks around 3:00 PM (O3: 60.4/100).
Tomorrow (10 August 2026): Air quality in Mountain Ash is fair. AQI improves to fair; PM2.5 decreases to good; NO2 decreases to good; O3 decreases to fair; PM1 decreases to good; all other pollutants stay as today. Pollution peaks around 5:00 PM (O3: 28.2/100). Airmine updates local air quality forecasts four times daily.
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Developed with support from the European Space Agency (ESA)’s Business Applications and Space Solutions (BASS) team
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Mountain Ash's air quality reflects its position within Rhondda Cynon Taf, with local traffic and the town's built-up core as the main contributors. Residential heating and light industry add a modest seasonal contribution, though southwesterly winds keep overall levels moderate. The A40 generates consistent traffic-related NO₂ and PM2.5, particularly during peak commuting hours.
Today - 9 August | Pollution peaks at 15:00
AQI:
Poor
60.4/100
PM2.5 (fine particles):
Fair
26.2/100
PM10 (coarse particles):
Good
7.2/100
NO2 (nitrogen dioxide):
Medium
44.2/100
O3 (ozone):
Poor
60.4/100
SO2 (sulfur dioxide):
Good
8.9/100
CO (carbon monoxide):
Good
0.0/100
HCHO (formaldehyde):
Good
12.8/100
PM1 (ultrafine particles):
Fair
32.9/100
Levels show the poorest local air quality during the day
Tomorrow - 10 August | Pollution peaks at 17:00
AQI:
Fair
28.2/100
PM2.5 (fine particles):
Good
6.9/100
PM10 (coarse particles):
Good
2.5/100
NO2 (nitrogen dioxide):
Good
9.9/100
O3 (ozone):
Fair
28.2/100
SO2 (sulfur dioxide):
Good
1.9/100
CO (carbon monoxide):
Good
0.0/100
HCHO (formaldehyde):
Good
3.8/100
PM1 (ultrafine particles):
Good
5.1/100
Pollen forecast in Mountain Ash
View pollen forecastFrequently Asked Questions
Is air quality bad in Mountain Ash right now?
On 9 August 2026, overall air quality in Mountain Ash is poor. AQI is the main air quality indicator at 60.4/100. Pollution peaks around 3:00 PM (O3: 60.4/100).
Will air quality be worse tomorrow in Mountain Ash?
On 10 August 2026, air quality conditions in Mountain Ash will be better than today, with AQI forecast at fair at 28.2/100. Pollution peaks around 5:00 PM (O3: 28.2/100).
When is air pollution at its worst in Mountain Ash?
If you're tracking air quality in Mountain Ash, expect it to move around quite a bit through the year. In summer, ozone can build up on sunny afternoons, though windier, warmer weather usually helps clear traffic-related pollution faster than in winter. Through the colder months, readings near the A40 often rise, since chimney smoke and stagnant air stop pollutants clearing away. The shoulder seasons generally bring the mildest readings of the year.
Are air quality levels in Mountain Ash based on measurements or forecasts?
It is forecasts derived by downscaling forecasts provided by EU’s Copernicus Atmosphere Monitoring Service (CAMS) by taking into account local conditions such as traffic patterns. CAMS bases its forecast on satellite measurements of particles and chemical compounds in the atmosphere. Airmine’s services were developed with support from the European Space Agency (ESA)’s Business Applications and Space Solutions (BASS) team.
Why doesn’t the forecast always reflect wildfire impacts?
Airmine’s forecast uses CAMS (Copernicus Atmosphere Monitoring Service) as its background atmospheric model. While CAMS includes wildfire emissions, these are derived from satellite observations and are not available in real time. During rapidly evolving wildfire events, there may therefore be a delay before increased emissions are incorporated into the model. As a result, the forecast may temporarily underestimate PM₂.₅ and other pollutants associated with wildfire smoke.
During rapidly evolving wildfire events, CAMS may lag by approximately 1–2 days before increased wildfire emissions are fully represented, which can lead to temporary underestimation of PM₂.₅ concentrations in Airmine’s forecast.
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Data provided by Airmine — Last update: 10 August 2026 at 02:34 CEST (Data is updated four times daily.)
This forecast is produced independently using Airmine's own atmospheric data and models.
Unless explicitly made clear, the content on this site has not been paid for by external organisations and is Airmine's sole responsibility.
Disclaimer: Forecasts are provided for informational purposes only and should not be relied upon as medical advice. Actual pollen and air quality conditions may vary from the forecast. If you have allergies, asthma, or another medical condition, consult a healthcare professional. Please see our Terms of Service for important information about limitations of liability.
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