Day-long drivers at risk of cardiovascular problems as a result of traffic pollution

Exposure to fine particles and pollutants that accumulate in cars driving at varying speeds in road traffic enhances the likelihood of thrombosis, inflammation and alters the regularity of the heart rhythm. A study published today in the journal Particle and Fibre Toxicology raises concerns about cardiovascular risks for vehicle drivers.

Michael Riediker, from The Institute of Occupational Health Sciences in Switzerland, collaborated with colleagues from a number of institutions in North Carolina, USA, to study the direct effects of different sources of motor vehicle-related pollution on patrol officers. State troopers were chosen because they have a heavy exposure due to their day-long driving. The authors analysed the sources of pollutants inside the patrol cars of nine healthy young male patrol officers working on North Carolina highways. ON the basis of previous findings, the researchers concentrated on particles less than 2.5 micrometers in size (much smaller than a hair), which can deposit deeply in the lungs. They found that the particles accumulated during driving came from several sources, which could be identified by the presence of certain elements. They found silicon and aluminium from wear of the road surface, while another source was wear and tear of mechanical automotive parts, which produces particles containing iron, chromium and titanium. Gasoline combustion was also identified as a source, given the presence of benzene and the gas carbon monoxide, and driving at varying speeds in traffic raised levels of particles containing copper, sulphur and aldehydes. The heart rate of the troopers was measured during and after their shifts. Blood samples were collected after each shift to monitor inflammation and clotting status.

The results of the study show that pollution from speed-changing traffic had the most significant impact on the markers of cardiovascular health of the subjects. Driving in speed-changing traffic resulted in an increase in inflammatory cells and proteins, an activation of clotting (pro-thrombotic) pathways, an increase in red blood cell volume and a more variable heart rhythm. But the authors stressed that “answering the question, which of these sub-sources was causing the effects, would require a larger number of subjects or targeted toxicological studies”.

Extended inhalation of motor vehicle-related air pollution is known to increase daily deaths and hospitalization for cardiovascular diseases in the US and throughout the world – estimates put the death toll at 800,000 per year worldwide. Although their study was small and presents some limitations, the authors conclude that exposure to pollution caused by speed-changing traffic affects cardiovascular risk through effects on the heart rhythm and the blood clotting pathways.