§ Mr. Baker
To ask the Secretary of State for the Environment, Transport and the Regions, pursuant to the answer to the hon. Member for East Worthing and Shoreham of 24 May 2000,Official Report, column 539W, on dioxin, what recent assessment his Department has made of the effectiveness and accuracy of the programmes which monitor dioxin levels; and if he will make a statement. 
§ Mr. Meacher
[holding answer 19 June 2000]: There are 210 dioxin and furan compounds, of which 17 are thought to have toxicological consequences. Each of these 17 compounds is measured, weighted according to its relative toxicity and aggregated to give a single result in terms of the toxic equivalence of the total mix. These measurements are made over each quarter of the year, and the uncertainty of an individual quarterly dioxin measurement in air has been assessed as 19 per cent., expressed in terms of the overall toxic equivalent. The corresponding annual mean value has an uncertainty of 9 per cent.