Influence of distinct mobility scenarios on NO₂, PM_2.5 and PM₁₀ street-level concentrations — A case study in a Brazilian urban neighborhood

Atmospheric pollution is one of the world's largest environmental health threats in urban areas. High concentrations may occur especially in urban canyons due to the combination of traffic emissions and limited dispersion. In this study, the MUNICH model is employed to evaluate the influence of traffic emission in an urban neighborhood in Brazil on PM₁₀, PM_2.5 and NO₂ concentrations. Background concentrations were obtained using the CMAQ model and traffic emissions for each street were obtained using the local emission inventory. Volatile organic emissions were chemically speciated following factors in the literature established specifically for Brazilian fuels. MUNICH was capable of properly modeling NO₂ concentrations at the street level after correcting overestimated background concentrations. Simulations indicate mean spatiotemporal concentrations 3 and 2.2 times higher for PM₁₀ and PM_2.5, respectively, when resuspension is included on the total traffic emission. Finally, three scenarios are proposed to investigate the efficiency of specific mobility changes to reduce pollutant concentrations. All scenarios presented violations to WHO air quality guidelines. Particularly, comparison of time series of modeled concentrations to the recommend WHO's limits presented more than 900 exceedings for analyzed pollutants in the reference scenario. Even for reduced traffic emissions scenarios, exceedings to WHO's limits are still high for all simulated pollutants. Smaller number of violations is obtained when national standards is considered, which indicates that Brazilian legislation needs to be updated. Therefore, performed simulations suggest a potential non-health air and emphasize the need of more restrict politics to reduce air traffic emission in urban areas.