Brake Pad Emissions May Be More Harmful Than Diesel Fumes

Brake Dust Toxicity Compared to Diesel Exhaust

A recent study from the University of Southampton reveals that microscopic particles emanating from certain types of brake pads can be more toxic than those found in diesel vehicle exhaust. This research highlights that brake dust, a leading contributor to non-exhaust vehicle emissions, poses significant health risks as these emissions are largely unregulated by current legislation. The study’s lead author, Dr. James Parkin, emphasizes the need for more awareness regarding pollution from brakes, especially as the automotive industry shifts towards electric vehicles (EVs). While EVs are often perceived as having zero emissions, they still generate particulate matter (PM) through the wear and tear of brakes, tyres, and roads.

The Rise of Non-Exhaust Pollution

Historically, research has primarily focused on exhaust emissions from cars, vans, and trucks, which are known to elevate the risks of lung and heart diseases. However, the increasing contribution of non-exhaust pollution sources to overall vehicle particulate matter emissions—particularly from brake pads—has garnered attention in this latest study. This non-exhaust particle pollution has become the dominant source of vehicle PM emissions in the UK and parts of Europe.

Examining Brake Pad Toxicity

The researchers explored the effects of PM derived from four distinct types of brake pads: low metallic, semi-metallic, non-asbestos organic, and hybrid-ceramic. They concentrated on the finest particles, specifically PM2.5 and smaller, which are more than 30 times smaller than a human hair and can penetrate deep into the lung’s air sacs, the site for gas exchange between oxygen and carbon dioxide and the bloodstream. These fine particles have been associated with over four million premature deaths annually worldwide.

Laboratory Findings on Health Impacts

In the laboratory, lung cell samples were exposed to brake pad particulate matter to assess its impact, focusing on various harmful effects such as oxidative stress, inflammation, and cell death. The results indicated that non-asbestos organic brake pads inflicted the most inflammation and toxicity upon human lung cells, surpassing even that of diesel exhaust particles. Ceramic brake pads were identified as the second most toxic. Both of these types of pads exhibited high copper levels, which later experiments indicated were significant contributors to their toxicity.

Reducing Harmful Brake Emissions

The findings, published in Particle and Fibre Toxicology, propose that reducing copper concentration in brake pads could diminish some harmful effects tied to vehicle particulate matter. The health implications are significant, as air pollution from vehicles has been linked to various respiratory and cardiovascular diseases, as well as conditions like asthma, chronic obstructive pulmonary disease (COPD), and even dementia.

Policy Implications for Electric Vehicles

Project supervisor Professor Matthew Loxham noted the broader implications of this research concerning health and policy. As society transitions from diesel and petrol vehicles to electric ones, the dynamics of non-exhaust emissions will need to be considered seriously. He cautioned that non-exhaust emissions could potentially increase due to the heavier weight of electric vehicles, leading to greater friction and consequently more particulate matter.

The Need for Updated Regulations

Ultimately, the study highlights that while the electrification of the vehicle fleet may reduce some forms of emissions, it will not eliminate all health risks associated with vehicle-generated pollution. Current regulations focused primarily on exhaust emissions may be inadequate to address the extensive health threats posed by non-exhaust sources, necessitating a reassessment of legislative measures to ensure public health is adequately protected in this changing automotive landscape.