Independent and interactive effects of personal light exposure and air pollution on incident COPD: A prospective...

Chronic obstructive pulmonary disease (COPD) is a leading contributor to the global burden of respiratory disease. Ambient air pollution is a well-established environmental risk factor for COPD. However, the association between personal light exposure and incident COPD, as well as its potential interaction with air pollution, remains unclear. This study involved 86,080 participants from the UK Biobank with approximately 13 million hours of light sensor data. We employed Cox proportional hazards models to evaluate the associations of personal day and night light exposure with COPD risk and to examine the potential mediating role of rest-activity rhythms (RARs) and interactions with air pollution. Light exposure was categorized into four groups according to the percentile distribution of light intensity in lux: 0-50% (reference group), 50-70%, 70-90%, and 90-100%. Compared with the lowest exposure group (0-50%), brighter day light exposure was associated with a lower risk of COPD (50-70%: HR [95% CI], 0.88 [0.77, 0.99]; 70-90%: 0.82 [0.71, 0.95]; 90-100%: 0.72 [0.60, 0.88]). In contrast, brighter night light exposure was associated with a higher risk of COPD (70-90%: 1.16 [1.02, 1.31]; 90-100%: 1.41 [1.23, 1.63]). Mediation analysis suggested that RARs may partially account for these associations. Furthermore, significant additive interactions were observed between night light and air pollution. Personal light exposure may be an important modifiable environmental factor associated with incident COPD, with RARs potentially accounting for part of these associations. Notably, the association between night light exposure and COPD risk was stronger among participants exposed to higher levels of air pollution. These findings suggest that reducing night light exposure may have implications for respiratory health, particularly in highly polluted environments.