Ambient air pollution and pulmonary vascular volume on computed tomography: the MESA Air Pollution and Lung cohort studies

Background Air pollution alters small pulmonary vessels in animal models. We hypothesised that long-term ambient air pollution exposure would be associated with differences in pulmonary vascular volumes in a population-based study. Methods The Multi-Ethnic Study of Atherosclerosis recruited adults in six US cities. Personalised long-term exposures to ambient black carbon, nitrogen dioxide (NO 2 ), oxides of nitrogen (NO x ), particulate matter with a 50% cut-off aerodynamic diameter of 2.5 ) and ozone were estimated using spatiotemporal models. In 2010–2012, total pulmonary vascular volume was measured as the volume of detectable pulmonary arteries and veins, including vessel walls and luminal blood volume, on noncontrast chest computed tomography (TPVV CT ). Peripheral TPVV CT was limited to the peripheral 2 cm to isolate smaller vessels. Linear regression adjusted for demographics, anthropometrics, smoking, second-hand smoke, renal function and scanner manufacturer. Results The mean±sd age of the 3023 participants was 69.3±9.3 years; 46% were never-smokers. Mean exposures were 0.80 μg·m −3 black carbon, 14.6 ppb NO 2 and 11.0 μg·m −3 ambient PM 2.5 . Mean±sd peripheral TPVV CT was 79.2±18.2 cm 3 and TPVV CT was 129.3±35.1 cm 3 . Greater black carbon exposure was associated with a larger peripheral TPVV CT , including after adjustment for city (mean difference 0.41 (95% CI 0.03–0.79) cm 3 per interquartile range; p=0.036). Associations for peripheral TPVV CT with NO 2 were similar but nonsignificant after city adjustment, while those for PM 2.5 were of similar magnitude but nonsignificant after full adjustment. There were no associations for NO x or ozone, or between any pollutant and TPVV CT . Conclusions Long-term black carbon exposure was associated with a larger peripheral TPVV CT , suggesting diesel exhaust may contribute to remodelling of small pulmonary vessels in the general population.