Work

Long-term exposure to black carbon and incident asthma and chronic obstructive pulmonary disease in adults: The Danish Nurse Cohort

Year: 2025

Type: article

Abstract: Air pollution is a known risk factor for chronic respiratory diseases, including asthma and chronic obstructive pulmonary disease (COPD). However, evidence regarding the role of black carbon (BC) remains mixed and sparse. This study aimed to examine the association of long-term exposure to air pollution, focusing on BC, with incident asthma and COPD in adults. We followed 28,731 female nurses from the Danish Nurse Cohort from baseline (1993/1999) until the end of 2018, tracking their first-ever hospital contact (inpatient, outpatient, or emergency visit) for asthma or COPD. Annual mean concentrations of BC, fine particulate matter (PM 2.5 ), and nitrogen dioxide (NO 2 ), were modeled since 1979 onward using the Danish DEHM/UBM/AirGIS modeling system and assigned to time-varying residential addresses. Time-varying Cox models were used to assess the association between 3-year running mean air pollution and incident asthma and COPD, adjusting for individual and area-level covariates. Over an average follow-up of 23 years, 633 nurses developed asthma, and 1,145 developed COPD. We found long-term exposure to BC was consistently associated with increased risks of both asthma and COPD, with hazard ratios (HR) per 0.34 μg/m 3 (interquartile range) increase in BC of 1.06 (95% confidence interval: 1.00-1.13) for asthma and 1.04 (0.98-1.11) for COPD. These associations persisted and strengthened after controlling for total PM 2.5 or non-BC PM 2.5 . Stronger associations of air pollution were observed among individuals with underlying comorbidity. We observed that BC is an independent risk factor for developing chronic respiratory diseases, such as asthma and COPD, and BC may play a more significant role than PM 2.5 . This underscored the need for targeted air quality regulations to reduce BC emissions, which may have a greater impact on mitigating the burden of chronic respiratory diseases than focusing solely on PM 2.5 . • Long-term exposure to black carbon increased the risk of developing asthma and COPD in adults. • Associations with black carbon were linear, and independent of PM 2.5 . • Individuals with overweight, CVD or other chronic respiratory disease were more vulnerable to the adverse association of air pollution.

Source: Environmental Research

DOI: 10.1016/j.envres.2025.123357