Factors Associated with Middle-Aged Adult Obstructive Lung Function Deficits in the Grass Pollen Season

Background: Impact of grass pollen season (GPS) on lung function is not well-studied at a community level. We assessed this in middle-aged participants from the Tasmanian Longitudinal Health Study (TAHS), and potential modifiers of this association. Methods: Spirometry was performed at the TAHS 53-year follow-up (n=2478). We compared lung function for those tested in the GPS (Oct-Jan) to those tested outside GPS using linear regression. Interactions were investigated for: questionnaire-reported asthma, hay fever, eczema and grass pollen allergy symptoms in the past 12 months; traffic-related air pollution (TRAP) exposure defined by living <200m from a major road; and glutathione S-transferase (GST) polymorphisms (GSTM1, GSTT1, GSTP1) for a subsample. Results: An association between GPS and reduced lung function was observed among those with allergic disease, also those living <200m from major roads or with a GSTM1 genotype (p for interaction ≤0.1). Participants with current asthma tested in the GPS had increased mid- to small-airway obstruction compared to out of GPS, with zFEV1/FVC ratio = -0.3 (95% CI = -0.6,-0.1) and zFEF25-75% = -0.4 (95% CI= -0.6,-0.07). Similar evidence of obstruction was observed in current hay fever, eczema, grass pollen allergy or living <200m from major roads. A modest association was found with bronchodilator responsiveness = 18 ml (95% CI = -18,54) in those with GSTM1 null genotypes. Conclusion: Middle-aged adults with allergic disease or TRAP exposure may be more susceptible to obstructive lung function deficits during the grass pollen season. Genetics may also play a role, but further research on this is required.