Health impact of non-exhaust particles from road transports

Air pollution causes around 4.2 million premature deaths worldwide every year [1]. Several studies have demonstrated the harmful effects of poor air quality on health: onset of respiratory diseases [2], cardiovascular problems [3] and neurological disorders [4]. For traffic-related pollution, exhaust emissions are widely studied and their level is actually in decrease, thanks to relevant policies. Still, this is not the case for non-exhaust emissions (brakes, tires, pavement, vehicle components and re-suspension phenomena), which account for the majority of particulate emissions [5]. In order to characterize the non-exhaust emissions and to evaluate their potential toxicity, two industrial partnerships have been set up. Indeed, braking tests were carried out in the laboratory as part of the INSA - VOLVO Chair collaborative project and additional tests were performed with a system directly integrated into the vehicle to analyze particles from tire-road contact within the framework of the INSA - MICHELIN Chair.

For each test, we used an innovative collection system developed in the laboratory, allowing us to capture particles from the brakes or tires directly into a culture medium or a biomimetic surfactant (a new device developed under the Pulsalys DPPA project). This setup also includes a particle counter, with particle size range from 10 nm up to 10 µm, enabling particle size distribution analysis during the tests, along with a carbon tab for particle collection, which is subsequently examined using SEM-EDX to determine the particles’ composition. In order to identify the health impacts of the collected non-exhaust particles, the effect of the collection media on cellular viability was evaluated using RAW264 macrophages cell line. Changes in the physicochemical properties of pulmonary surfactant, as well as the biophysical properties of cells, upon contact with non-exhaust particles were also evaluated.

The collected non-exhaust particles did not show a significant impact on cell viability. However, using a fluidity marker (DIOLL), we detected changes in cell biophysical properties and surfactant structure: indeed, cells in the presence of particles became more rigid, while pulmonary surfactant in the presence of particles became more fluid.

This study underlines thus a significant disturbance in cell metabolism and cellular homeostasis, despite an apparently unaffected cell viability. The observed biophysical changes seem to represent an early marker of chronic pathologies such as cancer or pulmonary fibrosis.

 

[1] Fuller et al, “Pollution and health: a progress update,” Lancet Planet Health, vol. 6, pp. 535–547, 2022.

[2] Caillaud et al, “Outdoor pollution and its effects on lung health in France,’’ Revue des Maladies Respiratoires, vol. 36, p. 1150—1183, 2019.

[3] Lelieveld et al, “Cardio- vascular disease burden from ambient air pollution in europe reassessed using novel hazard ratio functions.,” European Heart Journa, vol. 40, p. 1590–1596, 2019.

[4] Piguet, “Neurosciences grand public pollution environnementale maladies du cerveau : Les pistes actuelles,” NeuroCampus, vol. Brochure 1, 2018.

[5] Martini, “Scientific evidence on vehicle’s emissions,” The European Commission’s science and knowledge service, 2018.