TY - JOUR T1 - Work in brief JF - Occupational and Environmental Medicine JO - Occup Environ Med SP - 717a LP - 717a VL - 63 IS - 11 AU - Keith Palmer Y1 - 2006/11/01 UR - http://oem.bmj.com/content/63/11/717a.abstract N2 - Questionnaires are often used to assess children’s residential exposure to environmental tobacco smoke (ETS), but with the potential to misclassify through recall and response bias. How much these errors matter is the topic of a paper by Gehring et al.1 They have compared questionnaire responses with measures of nicotine in air and levels of urinary cotinine. The study surveyed 347 German, 335 Dutch and 354 Swedish pre-school and school children. Despite some misclassification, questionnaire responses were found to provide a valid, as well as an inexpensive and convenient estimate of residential ETS. The proportion of … ER -