Preconception air pollution exposure and early onset asthma and hay fever in the offspring

Background: Knowledge is scarce on cross-generational health effects of air pollution. Aim: To investigate effects of low levels of air pollution on asthma and hay fever across two generations. Methods: In the Swedish centres (Umea, Uppsala, Gothenburg) of the RHINESSA study we had air pollution exposures for 654 parents born after 1975 (mean age 35 years, range 21-40) and their 1104 offspring (mean age 5 years, range 0-23). We analysed the outcomes early onset asthma and hay fever in offspring. Mean annual exposures of PM2.5, PM10 and NO2 (µg/m3) were calculated for parents 0-18 years and for offspring 0-10 years. We performed multilevel logistic regression analyses clustered by family, stratified by parental and offspring sex and adjusted for parental asthma and education. Results: 12% sons and 10% daughters had early onset asthma, 7% sons and 6% daughters hay fever. After adjustment for covariates (Table 1), PM2.5 exposure in mothers was associated with early onset asthma in sons (OR 1.46, 95%CI 1.03-2.08). For fathers, PM2.5 was associated with hay fever in daughters (OR 2.73, 95%CI 1.34-5.58). PM10 and NO2 was not associated with any of the outcomes. Offspring’s own pollution exposure was not a significant risk factor. Conclusions: Preconception air pollution exposure in mothers and fathers during their first 18 years of life may be an important risk factor for early onset respiratory diseases in the offspring.