LONG-TERM exposure to urban environmental factors, particularly air pollution, lack of green space, and dense built environments, significantly increases the risk of developing asthma across the life course, according to a large-scale analysis involving 14 European cohorts and more than 340,000 participants.
This prospective study, part of the EXPANSE project, examined how different components of the “external exposome”, defined here as ambient air pollution, built environment characteristics, and temperature, are associated with incident asthma in both childhood and adulthood. Researchers used baseline residential addresses to assign exposure levels and grouped participants into domain-specific clusters using k-means clustering. Environmental risk scores were calculated by combining all three domains, offering a comprehensive estimate of cumulative environmental exposure.
Among 349,037 individuals, 7,428 developed asthma over the study period. Adults exposed to higher levels of particulate matter (PM) and nitrogen dioxide (NO₂) had a 13% increased risk of asthma (OR_meta = 1.13, 95% CI: 1.01–1.25). Both children and adults residing in areas with dense urban structures and limited greenness also experienced elevated asthma risks (OR_meta = 1.36, 95% CI: 1.14–1.64 for birth cohorts; OR_meta = 1.15, 95% CI: 1.03–1.28 for adults).
When combining all three domains into a single environmental risk score, asthma risk rose by 13% in children and 15% in adults per 20% increase in score. Notably, 11.6% of new asthma cases were attributable to environmental risk scores above the cohort-specific median.
These findings reinforce the growing understanding that asthma is not solely a genetic or allergen-triggered condition but is also driven by a complex interplay of environmental factors. The authors emphasize that urban planning efforts that reduce air pollution and enhance green spaces may offer a critical avenue for asthma prevention across the population.
Reference:
Yu Z et al. External exposome and incident asthma across the life course in 14 European cohorts: a prospective analysis within the EXPANSE project. Lancet Reg Health Eur. 2025. https://doi.org/10.1016/j.lanepe.2025.100314 [Online ahead of print].
