Timing of secondhand smoke, pet, dampness or mould exposure and lung function in adolescence

Background The relevance of timing of exposure in the associations of secondhand tobacco smoke (SHS), pets, and dampness or mould exposure with lung function is unclear. We investigated the relevance of timing of these exposures for lung function in adolescence. Methods We used data from participants of the Dutch Prevention and Incidence of Asthma and Mite Allergy (PIAMA) cohort with spirometric measurements at ages 12 and 16 years (n=552). Data on residential exposure to SHS, pets, and dampness or mould were obtained by repeated parental questionnaires. We characterised timing of exposure through longitudinal patterns using latent class growth modelling and assessed associations of these patterns with FEV1 and FVC at ages 12 and 16 and FEV1 and FVC growth between ages 12 and 16 using linear regression models. Results Childhood SHS exposure was associated with reduced FEV1 growth/year (95% CI) (−0.34% (−0.64% to −0.04%)). Late childhood and early life pet exposure was associated with increased FEV1 growth (0.41% (0.14% to 0.67%)) and reduced FVC growth (−0.28% (−0.53% to −0.03%)), respectively, compared with very low exposure. Early life dampness or mould exposure was associated with reduced lung function growth. All time windows of SHS exposure tended to be associated with lower attained lung function and pet exposure tended to be associated with higher FEV1. Conclusion SHS exposure during childhood could lead to reduced lung function growth and lower attained lung function in adolescence. While pet exposure in late childhood may not adversely affect lung function, early childhood pet exposure may slow down FVC growth in adolescence.