Objective Despite extensive research on the detrimental effects of air pollution on respiratory diseases like asthma and chronic obstructive pulmonary disease, the impact on people with cystic fibrosis (CF) remains understudied. Our study aimed to quantify the association between air pollution exposure and lung function decline in people with CF in London, UK. Methods Using 10 years (2008–2017) of UK Cystic Fibrosis Registry data, we conducted a longitudinal cohort study to evaluate the association between air pollution and the rate of decline in percent predicted forced expiratory volume in 1 second (ppFEV 1 ) among people with CF. Residential postcode exposure was based on high-resolution models of particulate matter with a diameter of less than 2.5 μm (PM 2.5 ) and nitrogen dioxide (NO 2 ) from the London Air Pollution Toolkit. We estimated the temporal decline in ppFEV 1 in high, medium and low exposure subgroups based on air pollutant concentration tertiles using linear mixed models with random intercepts. Results We used 3333 ppFEV 1 measurements of 393 people with CF (122 children, 271 adults). Over 40% of these people with CF lived in postcodes falling into the most deprived national quintile. For PM 2.5 , the adjusted mean ppFEV 1 declined by 13.3% (95% CI −24.1% to −4.0%) over the study period in the high-exposure tertile compared with 8.5% (95% CI −11.7% to −6.4%) in the low-exposure tertile. Differences between the exposure groups were less consistent for NO 2 . Children and people with CF with severe genotypes seemed particularly vulnerable. Conclusions This study provides novel evidence of the detrimental impact of air pollution on lung function in people with CF. Our findings highlight the importance of addressing air pollution as a modifiable risk factor to improve long-term outcomes of people with CF, and the need for national studies of the impact of environmental factors on CF in the UK.
Khan et al. (Thu,) studied this question.