A window of opportunity: The importance of the timing of environmental exposures over the life course for asthma and lung function in adolescence

Environmental exposures such as secondhand smoke, air pollution, pets, and dampness or mould have been linked to adverse respiratory health effects, such as asthma and lung function deficits in children. Evidence for this is however limited in adolescents and the importance of the timing of these exposures over the life course is unclear. This thesis explored methods for characterizing longitudinal patterns of environmental exposures to assess relevance of the timing of exposure to secondhand smoke, pet, dampness or mould, and air pollution in the associations with asthma and lung function in adolescence.
Data were obtained from the Dutch Prevention and Incidence of Asthma and Mite Allergy birth cohort that was established in 1996/97. Data on lifestyle, health, environmental exposures, and household characteristics were collected using repeated questionnaires. Air pollution exposure was determined using Land Use Regression models. Three methods were used to characterize exposure: distinct time windows, cumulative scores and latent class modelling. The main outcomes were asthma, lung function growth and attained level of lung function in adolescence.
It has been shown that timing of exposure to secondhand smoke, pets, dampness or mould, and air pollution plays a role in lung function, and lung function growth in adolescence and that later exposures as well as continued exposure through the life course, in addition to early-life exposure, may play a role in respiratory health. There was no indication for specific relevant windows of exposure for asthma. This knowledge can be used to inform effective life course respiratory disease burden management.