the impact of atmospheric pollutants on the prevalence of atopic eczema in 6-7-year-old schoolchildren in spain; isaac phase iii.

atopic eczema (ae) is a chronic inflammatory skin disease that affects children and adults, and alters quality of life with a high morbidity rate and severe economic burden. the objective of the present work was to analyse specific atmospheric pollutants (o3, no, pm10 and so2) affecting the prevalence of diagnosed ae and its symptoms among 6-7-year-old schoolchildren. the participants included 21311 schoolchildren aged 6-7 years from 8 spanish regions, whose parents completed the isaac phase iii questionnaire to ascertain ae diagnosis and symptoms. the mean levels (µg/m3) of o3, no, pm10 (particles 10 micrometers or less in diameter) and so2 were determined in each geographical area participating in this study.  according  to  these  mean  levels, three  levels of  exposure  to  each  pollutant  were considered: level 1 (percentiles 0-25); level 2 (percentiles 26-74); level 3 (percentiles 75-100). exposure to o3  was associated with increased prevalence of rashes (exposure level 2, odds ratio (or): 1.22, 95% confidence interval (95%ci): 1.02-1.45; level 3 or:  1.33, 95%ci:1.10-1.61) and diagnosed ae (level 2, or: 1.27, 95%ci: 1.17-1.39; level 3 or: 1.27, 95%ci:1.15-1.41). an association was found between the level of no and a drop in the prevalence of diagnosed ae (exposure level 2, or: 0.88, 95%ci: 0.81-0.95; level 3 or: 0.85, 95%ci:0.74-0.97). there was also an association between the highest exposure level to pm10 and a reduced prevalence of rashes (level 3 or: 0.42, 95%ci: 0.22-0.81) and diagnosed ae (level 3or: 0.53, 95%ci: 0.38-0.75). future studies into exposure to  o3   and its relationship with allergic diseases may be conducted in order to prevent this association.