Association of early life and acute pollen exposure with lung function and exhaled nitric oxide (FeNO). A prospective study up to adolescence in the GINIplus and LISA cohort

Background: Pollen exposure has both acute and chronic detrimental effects on allergic asthma, but little is known about its wider effects on respiratory health. This is increasingly important knowledge as ambient pollen levels are changing with the changing global climate. Objective: To assess associations of pollen exposure with lung function and fractional exhaled nitric oxide (FeNO) at age 15 in two prospective German birth cohorts, GINIplus and LISA. Methods: Background city-specific pollen exposure was measured in infancy (during the first three months of life), and contemporary (on the day of and 7 days prior to lung function measurement). Greenness levels within circular buffers (100–3000 m) around the birth and 15-year home addresses were calculated using the satellite-derived Normalized Difference Vegetation Index. Regression models were used to assess the associations of grass and birch pollen with lung function and FeNO, and the modifying effects of residential greenness were explored. Results: Cumulative early life exposure to grass pollen was associated with reduced lung function in adolescence (FEV₁: −4.9 mL 95%CI: −9.2, −0.6 and FVC: −5.2 mL 95%CI: −9.8, −0.5 per doubling of pollen count). Acute grass pollen exposure was associated with increased airway inflammation in all children, with higher FeNO increases in children living in green areas. In contrast acute birch pollen exposure was associated with reduced lung function only in children sensitised to birch allergens. Conclusion: This study provides suggestive evidence that early pollen exposure has a negative effect on later lung function, which is in turn influenced by acute pollen exposures.