Short-term exposure to grass pollens is associated with airway inflammation in 1-2 days and airway obstruction in 2-3 days in people at risk of atopy due to their family history.
A study of 936 participants in the Melbourne Atopy Cohort compared the result of their clinical tests at the 18-year follow-up visit with environmental pollen data from the day of and three days prior to their testing.
Almost a third of participants had current asthma (30%), 13% reported current hay fever and 47% were sensitised to at least one grass pollen.
The study period covered three grass pollen seasons from September to February in 2009 to 2011. Although a minor thunderstorm asthma event occurred during the study period, none of the participants attended the clinic on or around this time.
The study, published in Allergy, found there were significant positive associations between grass pollen exposure and FeNO as a measure of airway inflammation at days 1 and 2.
As well there were significant inverse associations between grass pollen exposure and FEF25-75% and FEV1/FVC ratio at days 2 and 3.
Exposure to higher levels of grass pollen appeared to increase airway inflammation and airway obstruction in participants with current asthma compared to those with no asthma and in adults, but not in children or adolescents.
The study, from the Allergy and Lung Health Unit in the University of Melbourne’s Centre for Epidemiology and Biostatistics led by Professor Shyamali Dharmage, found adults and individuals with hay fever and pollen sensitisation may also be at higher risk.
“These findings are fundamental to inform individual and public health preventive strategies for asthma exacerbation and hospital admissions due to grass pollen exposure, such as a preventive asthma therapy or allergen immunotherapy,” the study authors said.