title: Before and after study designs.
authors.affiliation: Institute for Medical and Biomedical Education, St George's, University of London, London, UK p.sedgwick@sgul.ac.uk.
authors.forename: Philip
authors.initials: P
authors.lastname: Sedgwick
mesh_terms: D002648:Child; D006801:Humans; D010290:Parents; D012107:Research Design; D012111:Residence Characteristics / Q000706:statistics & numerical data*; D061845:Smoke-Free Policy / Q000331:legislation & jurisprudence*; D014028:Tobacco Smoke Pollution / Q000517:prevention & control* / Q000706:statistics & numerical data
chemical_list: D014028:Tobacco Smoke Pollution