§ Mr. Wigley
To ask the Secretary of State for the Environment how much sulphur dioxide there is on average and at maximum levels in the air in London.
§ Mr. Trippier
As part of the national pollution monitoring network, SO2 is measured at two sites in 482W London. The provisional annual mean and peak concentrations (in parts per billion) for 1989–90 are as follows:
Site Annual mean Peak Cromwell Road 16.6 185 Central London 10.7 226
Data for peak values should be viewed in the context of international agreements protecting human health, which specify mandatory concentration limit values linked to exposure for a period of time. SO2 concentrations are controlled by EC directive 80/779; the limit values it specifies have never been breached in London since the directive came into force.