Neighborhood allergenic trees and lung function from early adolescence up to early adulthood in Germany

We investigated whether having more birch trees or more allergenic trees around home in early adolescence was related to worse lung function up to early adulthood in the German cities of Munich and Dresden.

The analytic sample included 1539 participants from the population-based ISAAC II/SOLAR II study who were aged 9-11 at baseline and 19-24 at follow-up. Forced expiratory volume in one second (FEV₁), forced vital capacity (FVC), and FEV₁/FVC were measured by spirometry at both time points. The number of birch trees, allergenic trees, and total trees, along with tree cover density and the normalized difference vegetation index (NDVI) were calculated in 300 m buffers around home at baseline. The associations were assessed by generalized least squares regressions with a variance-covariance structure accounting for heteroscedasticity and within-subject correlations.

Participants living close to birch trees around age 10 tended to have slightly lower FEV₁ and FVC up to early adulthood. These associations were not restricted to participants with asthma or hay fever. Similar, though much attenuated, associations were found for allergenic trees. No associations were found for the other exposures of interest. We saw some effect modification by ozone, nitrogen dioxide (NO₂), and study town, but only for associations of NDVI with FEV₁.

Birch trees around the childhood home, as proxy of long-term exposure to allergenic birch pollen, were associated with slightly lower lung function up to early adulthood. Future studies on health effects of greenspace exposure should include species of plants.