Braking news – Driving and the Environment.
Excessive speed often ends with excessive braking leading to accidents or as in many cases, driving licence endorsements. But what many drivers fail to consider is the impact that they are causing to health and the environment.
Under normal braking conditions, a vehicle releases tyre and brake wear material into the air, so small that the particulate matter (PM) can be inhaled, adding considerably to urban air toxicity. It has been stated as an estimate that up to 55% of total brake wear and up to 10% of tyre wear emitted becomes airborne with the remaining percentages being deposited on the road, roadside or deposited on the vehicle, such as the vehicle’s wheels and wheel arches.
New taxes are being imposed in order to try to help reduce air pollution but are targeting the types of fuel used rather than looking at the total pollution a vehicle outputs. Previously councils embarked upon traffic calming measures such as speed bumps and chicanes but there is an argument that these only lead to further air pollution due to repeated acceleration and braking. It is worthwhile considering the causes of PM and identifying ways that can help to reduce it.
With the proliferation of road traffic of all kinds, brake and tyre performance has had to keep up with the increasing demands of vehicle size, weight and performance. Most passenger carrying vehicles are fitted with disc brakes at the front since up to 70% of the braking force is required there. Disc brakes have exposed brake pads so the PM is easily dispersed onto the road and into the air. Some vehicles have disk brakes on the rear axle as well with others having drum brakes where the brake pads, in this case, are not exposed, so the airborne PM is not emitted as easily. However, drum brakes have less braking efficiency.
Although the percentage of airborne PM from tyres is considerably less than brake wear, the fact is that an aggressive style of driving including speeding will dramatically reduce the mileage and lifespan of the tyre tread. The abrasive wear of a tyre on the road surface is known to contribute to the release of course to small particles on the road and roadside. But the airborne contribution, due to the thermomechanical process whereby hot spots on the tyre can release vaporised materials and upon cooling in the atmosphere, resulting in the production of inhalable PM.
There are other contributors, including road surface wear, corrosion and road deposits being repeatedly thrown up by passing vehicles. It is cited that electric vehicles will contribute more to tyre and brake PM because they are 20 to 30% heavier than conventional vehicles. A concerning factor considering the amount of drive there is towards electrification.
There are two main size groups of PM; course and fine. They can cause a range of health issues from lung irritation to more chronic lung disease, can affect the heart and lead to changes in the blood chemistry, also with consequences for the heart. The smaller PM in the fine group range can enter the bloodstream and depending upon the material can induce a number of illnesses.
For the environment, PM has effects upon ecosystems, vegetation, rivers, the nutrients in soil, woodland, forests and food production. Not excluding the consequences for insects and wildlife. Research continues and as it does there will be more and more cities introducing Toxicity Taxes, more regulations and enforced design changes for all methods of transportation.
But are there practical measures that can be taken now in everyday journeys? HR and Fleet Managers can help to limit the contribution that drivers and their driving styles and habits have on health and the environment, by engaging in frequent licence checking. This can help to reduce pollution by identifying drivers that have a history of speeding or dangerous driving and taking the appropriate action for correction.
Keeping to speed limits and driving in a safe way will limit excessive braking, swerving, hard cornering, resulting in less tyre and brake wear, less PM. The high-resolution brake lights are not just a warning for the following driver to keep a distance and slow down, but a warning for all drivers to consider their own, others and the environment’s health and safety.