Real-World Asphalt Pavement Emissions: Combining Simulation Chamber Measurements and City Scale Modeling to Elucidate the Impacts on Air Quality

Abstract

In this paper, the role of asphalt pavement emissions in urban air quality was assessed combining laboratory experiments and city-scale air-quality modeling. In particular, the emission factors (EFs) of volatile and intermediate volatility organic compounds (VOCs and IVOCs) of asphalt pavements were determined in an atmospheric simulation chamber. Relative humidity (RH) and simulated solar light UV-A radiation were found to play a key role in the emission of VOCs and IVOCs. RH significantly increased the EFs, and predominantly those of oxygenated VOCs, due to changes in the microphysical properties of the materials. Under UV-A radiation, EFs were enhanced, due to the photochemical process induced on the asphalt–air interface. IVOCs were found to account for up to 30% of the Total EFs measured. Considering Paris as a case study, asphalt emissions in air-quality simulations lead to an increase in organic aerosol concentrations of at least 3%, during average summer daytime conditions. We estimate this impact significantly higher, in case all the IVOCs emissions are included in the model. This highlights the significant influence of solar radiation on emissions from old asphalt when exposed to UV radiation and the impact on air quality during the summer.