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’ particulate episodes notification 4th to 9th March 2026 – Including Saharan Dust.
London experienced a sustained air pollution episode characterised by elevated particulate matter levels PM10 and PM2.5 from Wednesday 4th March to Monday 9th March. The episode was driven by a combination of continental urban, industrial and agricultural emissions, Saharan dust, and local atmospheric stagnation that prevented the dispersal of London’s own emissions. The presence of Saharan dust gave some vivid red sunsets due to dust scattering.
On Wednesday 4th March a south-easterly air feed which had spent time at low altitude travelling up through France from the Mediterranean resulted in an import of continental urban, industrial and agricultural emissions as well as Saharan dust. Chemical speciation analysis showed that the import of continental pollution made a significant contribution to pollution levels during the day.
On Thursday 5th into Friday 6th, we saw some of the highest Saharan dust particulate pollution of this episode. This was characterised by increased PM10 and Silica concentrations. The air feed again travelled up through France but originated further down in the Mediterranean. Continental pollution also contributed over this period but not to the same extent as on Wednesday, as particle to gas phase transition took place in strong sunshine and warmer temperatures on Thursday. All pollution levels reduced quickly Friday afternoon with the introduction of rain and a fresher, cleaner North Atlantic air feed via the North Sea.
Particulate levels began increasing again later on Saturday morning, 7th March, as an air feed from over the continent returned. Over the next couple of days pollution levels accumulated due to a combination of continental import, Saharan dust and recirculation and poor dispersion of local emissions. Highest particulate levels were measured Sunday night March 8th and early Monday morning.
From later Monday morning March 9th pollution levels begin to decrease in a faster moving, ‘cleaner’ air feed which had travelled from over western France. This fresher cleaner air acting as a mechanical sweep, ensuring the rapid dispersion of accumulated pollution and pushing it north eastwards, out over the North Sea. By Tuesday March 10th, all London monitoring sites had returned to measuring "Low".
John Casey
Erica Withers
(Duty Forecasters)
|
|
|
Back to Air Quality Home