Abstract: Road traffic non-exhaust emissions, such as tire, brake, and road wear, together with road dust resuspension, are increasingly contributing to the air pollution caused by particulate matter. However, these emissions remain unregulated. By introducing ultra-low emission and electric vehicles, non-exhaust emissions may become the sole origin of particulate matter from road transportation. This study presents a comprehensive inventory of tire, brake, and road wear emissions in Colombia from 1990 to 2020. The inventory is both temporally and spatially detailed, providing a high-resolution breakdown of these emissions. The estimation of PM2.5 and PM10 levels was conducted using a top-down methodology that considered specific local elements such as fleet technology, fuel consumption, road infrastructure, and activity factors at both national and departmental levels. Additionally, emission factor averages and uncertainties from several sources were taken into account. The spatial disaggregation was conducted at a resolution of 0.01° x 0.01°. While the emissions of PM2.5 from road wear were much higher compared to those from tire and brake wear, the emissions of PM10 were evenly distributed among all sources. Due to their inherent unpredictability, emissions fluctuate within a range that is 0.8 to 1.7 times higher than the anticipated mean value. The ratio between non-exhaust PM2.5 and PM10 is around 0.4. The proportion of PM2.5 emissions that are not from exhaust or total emissions increased from 11.5% to 14.5% between 1990 and 2010, and more rapidly from 14.5% to 21.4% between 2010 and 2020, due to advancements in fuel quality and combustion technologies. From 1990 to 2010, there was a decrease in the proportion of non-exhaust PM10 emissions contributed by heavy duty vehicles, from 51% to 34%. Similarly, their contribution to PM2.5 emissions decreased from 44% to 30%. Passenger vehicles only slightly decreased their contribution, going from 36% to 35% for PM10 and from 44% to 43% for PM2.5. Motorcycles, on the other hand, significantly increased their participation, rising from 4% to 17% for PM10 and from 3% to 14% for PM2.5. Buses also saw an increase in their contribution, going from 8% to 13% for both PM measures. Ultimately, light commercial vehicles made the least significant impact and experienced a decline from 1.2% to 0.2% for both PM parameters. Our findings indicate that the HTAP emission inventory greatly underestimates non-exhaust emissions, accounting for just 5-9% and 8-13% of our PM10 and PM2.5 estimations, respectively. The emissions dataset, which is disaggregated spatially, is accessible in a netcdf format within a publicly accessible repository.

Keywords: particulate matter; non-exhaust emissions; unregulated emissions, time series, spatial disaggregation.