PM10 emissions from tires: a disruptive estimate questioning present pollution mitigation strategies

Emissions from automotive internal combustion engines in the form of exhaust gases from the combustion of gasoline, diesel, liquefied petroleum gas or natural gas are widely recognized to represent the primary source of atmospheric PM10 pollution. Technological progresses in the design and manufacturing of road transport engines is progressively focusing toward both increasing their performance and energy efficiency and reducing their environmental impact. PM10 production from tires has significantly increased in the last ten years. The present study aims at assessing the contribution to atmospheric PM10 pollution from tires and its overall environmental impact. More specifically, we aim at estimating this contribution in the top 10 populated cities in Italy. The research focuses on the years 2018 and 2020. Results indicate that atmospheric PM contribution from tires is larger than the contribution from exhausted gases (for example, 12.5 times larger in Bologna in 2018, 13.9 in Firenze in 2020, 11.8 in Torino in 2020) and that cities where tires' PM10 concentrations are larger than those from exhaust gas passed from 4 in 2018 to 6 in 2020. This implies the need to define specific mitigation strategies aimed at reducing PM10 emissions from tires, pushing toward the production of lighter vehicles, the use of narrower wheels and the promotion of public transport on rail and micro-mobility devices. The verification of results is based on the comparison between the total amount of PM10 particles emitted by vehicles’ tire, normalized by the surface of each municipality, and the measured PM10 mean annual concentrations.