Cardiff Air Quality 2025Real-Time PM2.5 Monitor & Pollution Data
Check Cardiff air quality in real-time with live PM2.5, NO2, and traffic pollution monitoring for Wales. Expert guide to improving indoor air quality in your Cardiff home.
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Cardiff Air Quality Overview 2024-2025
✅ Significant Improvement
All monitoring sites across Cardiff recorded NO₂ below 40 µg/m³ (national legal limit) in 2024. Castle Street achieved 30 µg/m³ annual average, down from previous hotspot levels.
📊 PM2.5 Levels
Current PM2.5 levels approximately 5 µg/m³, meeting WHO guidelines. All three automatic monitoring sites (Frederick Street, Richards Terrace, Castle Street) well within legal limits.
⚠️ No Clean Air Zone Charges
Cardiff rejected implementing a charging Clean Air Zone in 2019. Instead, the council invested £32 million in alternative measures:
- • Electric bus replacement (£1.8m)
- • Bus retrofitting to Euro 6 standards (£1.4m)
- • Castle Street & Westgate Street redesign (£18.9m)
- • Castle Street closed to private vehicles (bus-only route)
🏙️ Cardiff Pollution Hotspots & Major Roads
M4 Motorway Access
M4 junctions 30, 32, and 33 provide access to Cardiff city centre. No charging restrictions on M4 or city centre routes, though through-traffic restrictions exist in the city centre (not charging-based).
Castle Street (Former Hotspot)
Previously a pollution hotspot, now closed to private vehicles as a bus-only route. 30 µg/m³ annual NO2 average in 2024, showing significant improvement from historical levels.
Newport Road & Westgate Street
Major arterial roads benefiting from £18.9m redesign. Part of city centre improvements contributing to overall air quality gains.
Air Quality Management Areas (AQMAs)
Cardiff had 4 AQMAs due to NO2 exceedances. Due to sustained improvements, 3 of 4 AQMAs may be revoked in 2025-2026. Llandaff AQMA eligible for revocation in 2026.
Improve Your Cardiff Indoor Air Quality
Even with outdoor improvements, Cardiff homes near M4, Castle Street, or Newport Road can benefit from indoor air purification. MERV13/16 filters and HEPA purifiers remove traffic pollution, PM2.5, and allergens.
🧮 Calculate Your Needs
Use our free ACH calculator to determine the right purifier size for your Cardiff home.
Try ACH Calculator →🛒 DIY or Shop Ready
DIY builds from £149 or shop MERV13/16 purifiers. Use code STAROFFER for 10% off.
Shop CleanAirKits →Frequently Asked Questions
What is the current air quality in Cardiff?
Cardiff's air quality in 2024 shows significant improvement, with all monitoring sites recording NO2 below the 40 µg/m³ legal limit. Castle Street, previously a pollution hotspot, now averages 30 µg/m³. Current PM2.5 levels are approximately 5 µg/m³. Use our free live monitor above to check real-time Cardiff air quality, including PM2.5, NO2, and UK DAQI data updated hourly.
Does Cardiff have a Clean Air Zone?
No, Cardiff does not have a charging Clean Air Zone. In 2019, Cardiff Council rejected a CAZ and instead invested £32 million in alternative measures including electric bus replacement (£1.8m), bus retrofitting to Euro 6 standards (£1.4m), and Castle Street redesign (£18.9m). Castle Street is now closed to private vehicles as a bus-only route, contributing to improved air quality.
What are the main sources of air pollution in Cardiff?
Cardiff's main pollution sources are traffic from the M4 motorway (junctions 30, 32, 33), major roads like Castle Street, Newport Road, and Westgate Street, and through-traffic in the city centre. Historical hotspots included Castle Street and areas within the 4 Air Quality Management Areas (AQMAs), though 3 of these may be revoked due to sustained improvements.
How can I improve indoor air quality in Cardiff?
Improve Cardiff indoor air quality by using MERV13 or HEPA air purifiers (especially if living near M4 or Castle Street), monitoring outdoor pollution before ventilating, sealing windows during high-traffic periods, and maintaining 4-6 air changes per hour (ACH). Our free ACH calculator helps determine the right purifier size for Cardiff homes.