ENVIRONMENTAL factors in urban areas jointly drive a substantial burden of asthma, according to a large new European study evaluating exposures from birth to old age.
Researchers analysed data from 14 European population-based cohorts, encompassing over 349,000 individuals, to examine how multiple urban environmental exposures, specifically air pollution, the built environment, and ambient temperature, affect asthma incidence. Participants’ home addresses were linked with high-resolution environmental data, and clustering techniques were used to categorise distinct exposure profiles within each domain. Associations between these exposure clusters and new-onset asthma were assessed separately for birth and adult cohorts, and results were pooled via meta-analysis. An environmental risk score combining all three domains was also developed to estimate cumulative effects of the urban exposome.
Among the study population, 7,428 individuals developed asthma. Elevated asthma risks were found in adults living in areas with high particulate matter and nitrogen dioxide (ORmeta: 1.13, 95% CI: 1.01–1.25). Both adults and children residing in densely built-up areas with little green space were at increased risk (ORmeta: 1.36, 95% CI: 1.14–1.64 in birth cohorts; ORmeta: 1.15, 95% CI: 1.03–1.28 in adult cohorts). The combined environmental risk score was consistently associated with incident asthma: a 20% increase in the score corresponded to a 13% higher risk in birth cohorts (ORmeta: 1.13, 95% CI: 1.07–1.20) and a 15% higher risk in adult cohorts (ORmeta: 1.15, 95% CI: 1.10–1.20). On average, 11.6% of all new asthma cases could be attributed to exposures above the cohort-specific median environmental risk score, underscoring the impact of cumulative urban environmental burdens.
These findings provide compelling evidence that multiple, often co-occurring, urban environmental exposures contribute significantly to asthma development throughout the life course. Urban design that prioritises air quality and green space access may play a key role in asthma prevention.
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; DOI: 10.1016/j.lanepe.2025.101314.
