Free down load from here.
http://books.hse.gov.uk/hse/public/saleproduct.jsf?catalogueCode=9780717662289
which links on to
http://www.hse.gov.uk/pubns/priced/hsr25.pdf
http://books.hse.gov.uk/hse/public/saleproduct.jsf?catalogueCode=9780717662289
which links on to
http://www.hse.gov.uk/pubns/priced/hsr25.pdf