Natural mitigation factor adjustment for re-suspended particulate matter emissions inventory for Bogotá, Colombia

This work improves atmospheric emissions of particulate matter in Bogotá Colombia, and provides a tool applying this technique around the world. Bogotá's air pollution is largely impacted by particulate matter, and specifically by re-suspended particulate matter (RPM). RPM sources include paved and unpaved roads, agricultural tilling, construction activities, mining and quarrying. RPM emissions are frequently estimated using annual emission factors, time-varying vehicle traffic activity, a time/space invariant meteorological scaling factor, and a time/space invariant correction factor. This work updates the meteorological factors to be hour-specific, and replacing the correction factor with land use-specific local deposition factors. These techniques are codified in a flexible Python tool based on EPA's AP42 methods and the broader emission literature.Meteorology inhibits RPM emission directly via precipitation scavenging and indirectly by accumulation of road surface moisture. The effects of precipitation and surface moisture are parameterized as mitigation factors differently for paved and unpaved roads due to their porosity and drainage characteristics.These estimates of hourly mitigation factors (on average for paved roads: 0.86 and for unpaved roads: 0.61) agree well with annual factors previously used (paved: 0.90; unpaved: 0.60), however hourly factors have clear diurnal patterns that reduce emissions more significantly latter in the day for paved roads (00–12: 0.95; 12–24: 0.78), and to a lesser extent for unpaved roads (00–12: 0.64; 12–24: 0.58).Emissions are also significantly reduced by vehicle induced turbulence and local deposition. The transportable fraction (0.59 ± 0.22), parameterized based on land use, significantly reduced emissions and correlates with unpaved roads (r = 0.30) more so than with paved roads (r = 0.02). These fractions were used to construct a new inventory, which might improve air pollution predictions compared to the raw inventory, as well as new efforts to simulate exposure fields in Bogotá and our understanding of local particulate sources and sinks.