Pollution Episodes
Details of major pollution episodes including peak values recorded across
Ealing Council.
Please select an episode to view from the list below:
‘Moderate’ PM10 and PM2.5 Particulate Pollution Incident Notification for Monday 26th January 2026
This event marked the first significant Pollution Episode of 2026.
A widespread ‘Moderate’ particulate air pollution incident occurred yesterday, Monday 26th January. Elevated levels of PM2.5 and PM10 were measured across the London Air Quality Network, impacting all monitoring site types, including Kerbside, Roadside, Urban Background, and Industrial locations.
Observations and Measurements
During the peak of the episode, 34 sites recorded ‘Moderate’ levels for PM2.5 particulates, while 8 sites reached ‘Moderate’ for PM10. The episode was geographically broad, with the stagnant air mass ensuring that elevated concentrations were felt across the entirety of the Greater London area rather than being confined to specific traffic hotspots.
Causal Factors
The pollution build-up was driven by a combination of stagnant local meteorology and the transboundary transport of pollutants:
Meteorological Stagnation Monday was characterized by a dry outlook and still winds. These calm conditions significantly inhibited the dispersion of local pollutants, allowing London’s own emissions primarily from transport and domestic heating to accumulate at ground level.
Transboundary Import Back-trajectory modelling confirmed an air feed originating from France and Spain. This air mass imported a significant load of secondary particulate matter into the UK.
Combined Impact The primary driver of the episode was the merging of these imported pollutants with London’s local emissions. The lack of wind activity created a ‘trap’ effect, where the incoming continental plume combined with city-generated particulates, resulting in sustained ‘Moderate’ readings across the network.
Episode Conclusion
This episode has now concluded. As of Tuesday 27th January, particulate levels have returned to ‘Low’ across the network. This improvement is due to the return of a stronger westerly ‘clean’ air feed, which has effectively dispersed the accumulated pollutants and replaced the stagnant air mass with cleaner Atlantic air.
Erica Withers
Forecast Duty Officer.
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