Asbestos is a potent cause of disease and cancer. The symptoms of ill-health do not normally become apparent until 10 to 20 years (sometimes longer) after exposure. Because of its insulating and structural properties asbestos was widely used in the manufacture of building materials. Recognising the hazardous nature of asbestos the Government prohibited the importation of asbestos and products containing asbestos towards the end of the last century. It is no longer used in any manufacturing process and building materials purchased new since the year 2000 are asbestos free. Despite the prohibition many workers, particularly in the building trades, are still exposed to asbestos when they carry out work on materials that include asbestos; among these are pipes, pipe lagging and insulation, insulation board, ceiling tiles, floor tiles, roofing sheets and sprayed asbestos coatings on structural steelwork. The HSE suggests that in the UK 20 tradesmen a week are dying of asbestos related disease. Employers operating from pre-2000 buildings are required to prepare an Asbestos Management Plan. The plan will identify the presence or otherwise, following a survey, of asbestos containing materials. It will also contain a strategy for dealing with them to make sure that no-one is exposed to risk.