Greenness across the lifespan and adult respiratory health: A longitudinal cohort study

Source abstract

Background Greenness has been linked to improved health, but evidence on respiratory benefits from a life-course perspective remains limited. This study aimed to investigate the associations between life-course exposure to greenness and adult respiratory health in a Chinese population. Methods We analysed data from 39,780 participants aged 6-25 years in Taiwan, contributing 57,056 observations between 2000 and 2022. Among the 57,056 observations, 47.0% were from participants with follow-ups, and 23.1% from the life-course analytic subsample. Greenness was characterised using a two-year average Normalized Difference Vegetation Index (NDVI). Outcomes included both lung function impairment (restrictive pattern [RP], preserved ratio impaired spirometry [PRISm]) and individual spirometry measures (i.e., forced vital capacity [FVC], forced expiratory volume in one second [FEV 1 ], and maximal mid‑expiratory flow [MMEF]). Generalised linear mixed models were used to assess overall associations. A life-course modelling framework was applied to identify sensitive periods for adult respiratory health. Causal mediation analyses were conducted to evaluate PM 2.5 and physical activity as potential mediating pathways. Results We found that each interquartile range (IQR) increase in NDVI was associated with higher lung function: Each IQR increase in NDVI was associated with 17%-29% lower odds of lung function impairment, as well as higher lung function: 1.88% higher FVC (95% confidence interval [CI]: 1.62, 2.14), 1.99% higher FEV 1 (95% CI: 1.72, 2.25), and 1.92% higher MMEF (95% CI: 1.51, 2.32). Life-course framework demonstrated that the critical-period model provided the best fit, with greenness exposure during adolescence showing the strongest associations with adult respiratory outcomes. PM 2.5 mediated 4.83%-11.84% of the greenness-respiratory health association. Conclusions Greener environments were associated with improved respiratory health across development, with adolescence emerging as a potentially sensitive period. PM 2.5 reduction represents a key mediating pathway. These findings highlight the importance of sustained access to greenness from early life and support targeted urban planning strategies to promote long-term respiratory health.