Air Pollution Exposure and Daily Lung Function in COPD: Effect Modification by Eosinophilia.

Rationale Few studies have assessed personal exposure to pollutants and lung function among adults with COPD. Blood eosinophilia may be a biomarker of airway inflammation and pollution susceptibility. Objectives To evaluate if daily pollutant exposures are associated with lung function and if associations are modified by eosinophilia in COPD. Methods We recruited 30 former smokers with moderate-to-severe COPD living in the Boston area and followed them up to 4 non-consecutive months in different seasons. Participants measured morning lung function and carried a portable air quality monitor daily. Previous-day exposure to pollutants (PM2.5, NO2, and ozone) were measured by portable and community monitors. We constructed multi-level linear mixed-effects models with random intercepts for person and observation month, adjusted for temperature, humidity, age, sex, race, height, weight, income, and season, to assess associations of previous-day pollutant exposure with lung function and effect modification by eosinophilia ( 150 cells/µL). Results A total of 3,314 observations with exposure and lung function data were collected. Each IQR (5.1 ppb) higher previous-day personal exposure to NO2 was associated with a 11.3 mL (95% CI: -18.7, -4.0) lower FEV1 and a 18.0 mL (95% CI: -32.0, -4.2) lower FVC. Personal and community-level exposure to PM2.5 and community-level NO2 were negatively associated with FEV1 among the 55.2% of participants with eosinophilia (Pinteraction Conclusions Our study highlights the need to address air pollution exposure among COPD patients. Future research is needed to verify if eosinophilia is a biomarker for susceptibility to air pollution in COPD.