The purpose of this report is to review air quality in London during the 2nd quarter of 2004 and to report detailed measurement results for the year ended 30th June 2004.

During the quarter, 3 monitoring sites joined the London Air Quality Network (LAQN); Bexley 7, Bexley 8 and Sutton 3.

PM10 and O3 incidents were measured during the second quarter of 2004. However, the maximum concentration and duration of the incidents were less than those experienced during the same time period in 2003.

Provisional measurements during the year ending 30th June 2004 have been compared to the Air Quality Strategy (AQS) Objectives. Pollution measurements during the 12 month period are still affected by pollution incidents during 2003:

• The CO Objective was met at all CO monitoring sites.
• The annual mean NO2 Objective was exceeded at all road and kerbside sites in London except Enfield 2, Havering 1 and Havering 3.
• The annual mean NO2 Objective was also exceeded at background sites in inner and west London.
• The AQS Objective for O3 was exceeded at all permanent measurement sites in London except the kerbside site Marylebone Road and the urban background site Wandsworth 2.
• The incident -based PM10 AQS Objective was exceeded at 3 kerb/roadside TEOM sites in Inner and Central London, and at 3 TEOM sites situated alongside major arterial roads in Outer London. The two TEOM sites situated near the entrances to waste management facilities (Bexley 4 and Brent 5) also exceeded the incident-based PM10 AQS Objective. All background and suburban TEOM sites met the incident-based Objective.
• The annual mean PM10 AQS Objective was exceeded at the roadside TEOM site Bexley 4 and at the kerbside TEOM site Marylebone Road.
• The incident-based PM10 AQS Objective was exceeded at all kerbside and roadside BAM sites, and at 2 such sites in background locations. The annual mean PM10 AQS Objective was also exceeded at the Enfield 4 roadside BAM site.
• All sites met the AQS Objective for SO2.