Cardiff Bay, Caerdydd Air Quality Forecast - Today, Tomorrow
Air Quality Today
Today (11 October): Air quality in Cardiff Bay is moderate. AQI, PM2.5, and NO2 are moderate; PM10 and PM1 are fair; O3, SO2, CO, and HCHO are good. Pollution peaks around 7:00 PM (NO2: 44.2/100).
Air Quality Tomorrow
Tomorrow (12 October 2026): Air quality in Cardiff Bay is fair. AQI improves to fair; PM2.5 decreases to fair; PM10 decreases to good; NO2 decreases to fair; PM1 decreases to good; all other pollutants stay as today. Pollution peaks around 3:00 PM (NO2: 36.0/100).
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Air Quality
Today - 11 October
| Pollutant | Level | Value |
|---|---|---|
| AQI | Moderate | 44.2/100 |
| PM2.5 (fine particles) | Moderate | 43.2/100 |
| PM10 (coarse particles) | Fair | 28.9/100 |
| NO2 (nitrogen dioxide) | Moderate | 44.2/100 |
| O3 (ozone) | Good | 10.0/100 |
| SO2 (sulfur dioxide) | Good | 9.4/100 |
| CO (carbon monoxide) | Good | 1.0/100 |
| HCHO (formaldehyde) | Good | 13.6/100 |
| PM1 (ultrafine particles) | Fair | 26.5/100 |
Tomorrow - 12 October
| Pollutant | Level | Value |
|---|---|---|
| AQI | Fair | 36.0/100 |
| PM2.5 (fine particles) | Fair | 35.0/100 |
| PM10 (coarse particles) | Good | 19.6/100 |
| NO2 (nitrogen dioxide) | Fair | 36.0/100 |
| O3 (ozone) | Good | 6.0/100 |
| SO2 (sulfur dioxide) | Good | 5.8/100 |
| CO (carbon monoxide) | Good | 0.9/100 |
| HCHO (formaldehyde) | Good | 9.6/100 |
| PM1 (ultrafine particles) | Good | 16.8/100 |
Local Environmental Conditions
Around this site in Caerdydd, dense development means road traffic is the main local source of nitrogen dioxide and fine particles. Home heating, especially wood stoves and fireplaces, adds smoke and fine particles in the colder months. Pockets of trees and green space help filter a small share of the particles from traffic. Open water nearby lets breezes move freely across the area, helping to disperse pollutants.
Fine particle levels climb from December to March, as home heating and traffic combine with cold, still air averaging 6°C. By contrast, with summer temperatures averaging only about 17°C, ozone rarely becomes a serious problem. On the plus side, breezy weather in December, with winds near 25 km/h, tends to sweep pollution away.
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Frequently Asked Questions About Air Quality in Cardiff
Is air quality bad in Cardiff Bay right now?
On 11 October 2026, overall air quality in Cardiff Bay is moderate. AQI is the main air quality indicator at 44.2/100. Pollution peaks around 7:00 PM (NO2: 44.2/100).
Will air quality be worse tomorrow in Cardiff Bay?
On 12 October 2026, air quality conditions in Cardiff Bay will be better than today, with AQI forecast at fair at 36.0/100. Pollution peaks around 3:00 PM (NO2: 36.0/100).
When is air pollution at its worst in Cardiff Bay?
Fine particle levels climb from December to March, as home heating and traffic combine with cold, still air averaging 6°C. By contrast, with summer temperatures averaging only about 17°C, ozone rarely becomes a serious problem. On the plus side, breezy weather in December, with winds near 25 km/h, tends to sweep pollution away.
Are air quality levels in Cardiff Bay 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.
Understanding the Scale
The 0–100 air quality scores represent risk levels, not direct air pollutant concentrations. Higher scores indicate higher risk.
Air Quality
| Good | 0-20 | Low air quality risk. Air quality is expected to be good, with low levels of pollution. |
| Fair | 20-40 | Generally low air quality risk. Air quality is expected to be acceptable, with some pollution present. |
| Moderate | 40-60 | Moderate air quality risk. Air pollution is elevated and air quality may be less favorable. |
| Poor | 60-80 | High air quality risk. Air pollution is high and air quality is expected to be poor. |
| Very Poor | 80-100 | Very high air quality risk. Air pollution is very high and air quality is expected to be very poor. |