There are many sources of airborne particulate matter, including vehicle (mobile source) emissions, which include exhaust emissions, and non-exhaust emissions such as brake wear and tire wear.
To determine the contribution of TRWP to airborne particulate matter (PM), TIP sponsored sampling in urban and suburban environments to evaluate the presence of TRWP in PM10 and PM2.5. PM10 and PM2.5 are PM that have diameters of less than 10 and 2.5 micrometers respectively. These are size fractions that can become airborne, and particles of less than PM10 are inhalable to the lungs.
The conclusions of this study suggest that TRWP make minor contribution to airborne PM, comprising an average of less than 1 percent of particles in the PM10 and PM2.5 fractions sampled. Across all samples collected, the highest levels of TRWP detected comprised less than 3 percent of the PM10 fraction and less than 1 percent of PM 2.5.
TIP-sponsored risk assessment on the effects of exposure of mammalian species to TRWP have indicated that there is unlikely to be a risk to human health from exposure to TRWP in the air, and we’re engaged in continued research to improve this knowledge.
There are standardized methods to measure the contribution of TRWP to ambient air particulate matter (PM)
The International Organization for Standardization (ISO) published ISO Technical Specification (TS) 20593 (“Ambient air – Determination of the mass concentration of tire and road wear particles”) in June 2017. This standard is largely based on methodology that detects specific tire-related chemical markers in ambient air PM2.5 and PM10 (particulate matter (PM) that has diameter of less than 2.5 and 10 micrometers respectively).