Association of Short-Term Pollen Exposure With Lung Function in COPD Patients

Environmental exposures such as air pollution are well established triggers for chronic obstructive pulmonary disease (COPD) exacerbation and impaired lung function. However, the role of aeroallergens, particularly pollen, has not been thoroughly examined in COPD, despite evidence that pollen inhalation can cause airway inflammation. We investigated whether short-term exposure to higher concentrations of ambient pollen is associated with changes in lung function in people with COPD.

Thirty COPD participants, contributing 1808 observations, were enrolled in the Study of Pollution and COPD Exacerbation and completed 4 clinic visits over one year while performing daily spirometry during four 30-day seasonal periods. Ambient total pollen was measured regionally. Associations of short-term pollen exposure (lag 1–7 days and cumulative 3- and 7-day concentrations) with forced expiratory volume in 1 second (FEV₁) and forced vital capacity were assessed using distributed lag nonlinear models with a generalized additive mixed model. We tested if inflammatory biomarkers, inhaler medications, asthma history, and concurrent exposure ambient pollutants (nitrogen oxide, particulate matter diameter of 2.5 micrometers or less, ozone) modified associations between pollen exposure and lung function.

Pollen exposure at lag 3 day was associated with a lower FEV₁ (–5.5mL per interquartile range pollen increase; 95% confidence interval [CI]: –9.6, –1.3). Cumulative 3-day pollen exposure was similarly associated with a lower FEV₁ (–4.9mL; 95% CI: –9.6, –0.2). Associations of pollen and FEV₁ were greater in those with higher C-reactive protein and a diagnosis of asthma.

In this longitudinal study of people with COPD, higher short-term exposure to ambient pollen in the preceding 3 days was associated with a lower FEV₁. Our findings suggest that aeroallergen exposure may worsen airflow obstruction in people with COPD.