LAQN Pollution Episodes

Pollution Notification released on 13/02/2012

Throughout the first half of February 2012, London and the south east experienced elevated particulate levels due to an influx of polluted air from continental Europe combined with local emissions and calm cold weather conditions.

The episode started on Friday 3^rd February and continued until a change in air mass on the afternoon of Sunday 12^th February. Widespread 'moderate' PM₁₀ and PM_2.5 levels were recorded across the region on most days over this period, along with occasional 'moderate' NO₂ in some busy roadside locations.

The episode peaked over the weekend of 11^th and 12^th February, with 'high' PM₁₀ and PM_2.5 being recorded at a number of locations throughout London, including the monitoring site in suburban Teddington, highlighting the importance of regional pollution sources. This is the first time that 'high' PM_2.5 has been reported since the pollutant was added to Defra's Daily Air Pollution Index at the beginning of the year.

A change in air mass on Sunday afternoon brought north westerly winds and warmer air, causing levels to drop very rapidly from 2pm onwards.