Quantification of vehicle fleet PM₁₀ particulate matter emission factors from exhaust and non-exhaust sources using tunnel measurement techniques

Road tunnels act like large laboratories; they provide an excellent environment to quantify atmospheric particles emission factors from exhaust and non-exhaust sources due to their known boundary conditions. Current work compares the High Volume, Dichotomous Stacked Filter Unit and Partisol Air Sampler for coarse, PM₁₀ and PM_2.5 particle concentration measurement and found that they do not differ significantly (p = 95%). PM_2.5 fraction contributes 66% of PM₁₀ proportions and significantly influenced by traffic (turbulence) and meteorological conditions. Mass emission factors for PM₁₀ varies from 21.3 ± 1.9 to 28.8 ± 3.4 mg/vkm and composed of Motorcycle (0.0003–0.001 mg/vkm), Cars (26.1–33.4 mg/vkm), LDVs (2.4–3.0 mg/vkm), HDVs (2.2–2.8 mg/vkm) and Buses (0.1 mg/vkm). Based on Lawrence et al. (2013), source apportionment modelling, the PM₁₀ emission of brake wear (3.8–4.4 mg/vkm), petrol exhaust (3.9–4.5 mg/vkm), diesel exhaust (7.2–8.3 mg/vkm), re-suspension (9–10.4 mg/vkm), road surface wear (3.9–4.5 mg/vkm), and unexplained (7.2 mg/vkm) were also calculated. The current study determined that the combined non-exhaust fleet PM₁₀ emission factor (16.7–19.3 mg/vkm) are higher than the combined exhaust emission factor (11.1–12.8 mg/vkm). Thus, highlight the significance of non-exhaust emissions and the need for legislation and abatement strategies to reduce their contributions to ambient PM concentrations. - Highlights: • Calculations of exhaust/non-exhaust particulate emission factors using tunnel sampling and source apportionment techniques. • Non-exhaust emission dominates in the fine particle fraction, considered responsible for adverse human health impacts. • Emission factors for non-exhaust sources (e.g. tyre and brake) were calculated. • Fleet source PM₁₀ emission factor were also calculated, which can be used in dispersion modelling and health risk assessment. • Tukey mean-difference plot shows good fit of measured emission factors with NAEI 2008 emission factors. - Combined non-exhaust fleet PM₁₀ emission factor (16.7–19.3 mg/vkm) are higher than the combined exhaust emission factor (11.1–12.8 mg/vkm).