Non-exhaust emissions

Non-exhaust emissions come from wearing down motor vehicle brake pads, tires, roads themselves, and unsettling of particles on the road. This particulate matter is made up of micrometre-sized particles and causes negative health effects, including respiratory disease and cancer. Very fine particulate matter has been linked to cardiovascular disease. Multiple epidemiological studies have demonstrates that particulate matter exposure is associated with acute respiratory infections, lung cancer, and chronic respiratory and cardiovascular disease. Researchers have also found correlations between exposure to fine particulate matter and fatality rates in previous coronavirus epidemics. Studies have shown that non-exhaust emissions of particles from vehicles can be greater than particles due to exhaust. Brake wear gets released into the air as particulate matter. Standard frictional brakes on a vehicle function by virtue of the friction between a brake pad and a rotating disc or drum when the two are forced together by application of pressure to the braking system. The frictional process causes abrasion both of the brake pad and of the surface of the disc or drum leading to the release of particles, a substantial fraction of which become airborne. Particles on the road get thrown or blown into the air. Emissions from road dust suspension depend on a vehicles speed, size and shape, the porosity and amount of dust on road surfaces, as well as weather conditions. Considerable uncertainty remains regarding the amount of PM that is emitted by non-exhaust sources in real world driving conditions and how this amount varies with changes in the factors identified above. Rubber pollution gets released into the air. The surface of a tire when in contact with the road is steadily abraded by contact with the road surface. This leads to release of large quantities of small rubber particles which cover a wide ranges of sizes. The road itself wears and releases particulate matter into the air.