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Air pollution from diesel exhaust contains a mixture of both toxic chemicals and particulate matter. Many studies have found associations between exposure to diesel exhaust and subsequent poor health outcomes such as increased asthma, heart disease, and cancer. Findings from a new study suggest that brake dust air pollution may have some of the same harmful effects on health as diesel exhaust.
Brake dust is a form of air pollution that consists of metal particles generated from mechanical abrasion from brakes. These particles are small enough to be inhaled deep into the lungs, where they drive the production of reactive oxygen species, promoting inflammation and altering the function of immune cells. Approximately 20 percent of the particulate matter in air pollution is from brake dust.
The study was conducted in macrophages (a type of immune cell) exposed to brake dust obtained from a brake pad testing factory. Following exposure to the dust, the macrophages were challenged with a bacterial pathogen to determine the cells' ability to initiate an immune response and carry out phagocytosis, the process by which macrophages engulf and destroy pathogens.
The cells demonstrated dose-dependent decreases in mitochondrial depolarization (a process that inhibits the production of mitochondrial reactive oxygen species), increased secretion of immune-related cytokines, and decreased phagocytosis. Following 24-hour incubation in a brake pad particle-free environment, the macrophages regained their ability to carry out an appropriate immune response.
Although this research was performed in cells and future research will need to confirm the effects brake dust has on animals, these findings suggest that exposure to brake pad abrasion particles may be as harmful as exposure to diesel exhaust. They also highlight the importance of pollution mitigation strategies in public health interventions.