The literature searches identified 60 publications which together described the results of a total of 47 relevant epidemiological studies in children. Eighteen of the studies were conducted in the USA, four in Canada, 13 in Europe (in a total of 10 countries), five in Turkey or the Middle East, three in India or the Far East, three in Africa and one in New Zealand. Seven references were published as abstracts.
A further 17 publications described studies that seemed possibly relevant, but did not meet the inclusion criteria. The reasons for rejection included no actual data collected on ETS exposure, the study only reporting on whether tobacco smoke brought on wheezing (Speer, 1968), no results reported relating ETS exposure to aggravation of asthma (Wood et al., 1993; Huss et al., 1994; Chadwick, 1996; Gilliland et al., 2001; Morgan et al., 2004), results not reported separately for children (Tarlo et al., 2000; Bayona et al., 2002), results not reported separately for asthmatics (Lebowitz, 1984a; Lebowitz, 1984b; Toyoshima et al., 1987; Strachan et al., 1990; Agudo et al., 1994; Henderson et al., 1995; Fielder et al., 1999; Willers et al., 2000) and endpoint (respiratory illness) too broad (Gilliland et al., 2003). A further study (Bener et al., 1991) was rejected as the data presented seemed totally implausible, with 85% of a sample of schoolchildren reported to have asthma and the odds of having a frequent attack 34 times higher if one of the parents smoked.
The studies are described individually in sections 1.2 (USA), 1.3 (Canada), 1.4 (Europe), 1.5 (Asia) and 1.6 (Other). Section 1.7 then summarizes various relevant aspects of the studies considered and section 2 brings together the findings by type of endpoint.