This report summarizes the results of the air pollution monitoring carried out by the London Air Quality Network (LAQN) during 1998.

During 1998 the LAQN expanded rapidly with the addition of a further nine monitoring sites.

Rolling annual averages for carbon monoxide (CO), oxides of nitrogen (NOX), nitrogen dioxide (NO2) and particulate matter (PM10) have been analysed for the period November 1996 to November 1999. This analysis shows reductions in the rolling annual average concentrations of CO, NOX and PM10 across the LAQN. However, the NO2 rolling annual averages show little overall change.

In contrast with previous years, no significant pollution episodes occurred during 1998.

Each of the pollutants monitored by the LAQN in 1998 has been analysed in terms of their spatial distribution, and compared to the current and proposed Air Quality Strategy (AQS) objectives (DETR, 1999).

• The annual average objective for NO2 was exceeded at all roadside sites and inner London background sites.
• The current annual maximum hour objective for NO2 was exceeded at Marylebone Road and Sutton 2 only. The proposed incident based NO2 was exceeded at Marylebone Road only.
• Analyses of past data show that the current and proposed 'incident based' objectives were exceeded at a similar number of sites in three of the previous four years.
• The CO objective was exceeded at the Bromley kerbside site only.
• All London sites met the objective for sulphur dioxide. However, the objective was exceeded at Sevenoaks.
• The current PM10 objective was exceeded at all sites except Greenwich and St. Albans.
• The proposed PM10 objective was exceeded at Marylebone Road only.
• The objectives for benzene and 1,3 butadiene were met at all continuous monitoring sites.