Journal of Earth Sciences and Geotechnical Engineering

PM10 non-exhaust emission factors from road tunnel measurements considering deposition and resuspension

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• Abstract

   

  An improved understanding of PM non-exhaust sources from abrasion and resuspension processes is important for ambient air quality management and tunnel air management. Traffic tunnels are often used to assess real world air pollutant emissions. In contrast to ambient air quality measurements, flow and dilution conditions are well defined, vehicle speeds are typically constant. The aim of this work was to study the role of traffic volume on emission factors and to examine if PM10 deposition as opposed to resuspension needs consideration in road tunnel emission measurements. Data from two monitoring campaigns in a 10 km long tunnel with different distances between the air quality monitoring stations (3380 m/7180 m) have been re-analyzed. Neglecting potential prevailing sink processes, non-exhaust emission factors approach 0 with high traffic volumes or even non-physical negative values resulted. Significantly increased non-exhaust emission factors resulted by using an effective deposition velocity as a sink term accounting for the interplay of wall deposition losses and resuspension of PM10. Average light vehicle (LV) PM10 non-exhaust EF ranged between 0.015 g/km/LV (35000 LV/day) to 0.060 g/km/LV (6500 LV/day). Average heavy duty vehicle (HV) PM10 non-exhaust EF ranged between 0.080 g/km/HV (6000 HV/day) to 0.300 g/km/HV (1500 HV/day).