Building removal of particulate pollutant plume during outdoor resuspension event

• Building removal of particulate pollutant plume is modeled.
• Size-resolved removal rate and removal fractions are estimated.
• Factors affecting building removal and indoor air quality are investigated.
• The reduction of pollutant plume by high density building clusters is discussed.

The capacity of buildings to reduce the outdoor pollutant level during particle transport has not been thoroughly investigated. This study demonstrates that CFD modeling combined with multizone modeling can provide a complete picture on the fate and transport of PM pollutant plume passing a building. A plume intersecting a 6 m × 6 m × 6.3 m building with concentrations of 56, 93, 93, and 74 μg/m3 for 0.85 μm, 2.63 μm, 3.94 μm, and 8.77 μm particles, respectively, is simulated. The building removal rates are 79 ± 4 mg/h, 182 ± 10 mg/h, 209 ± 12 mg/h, 280 ± 26 mg/h, which are 0.1%, 0.13%, 0.15%, and 0.25% of the plume source emission rates, respectively. The building removal is mainly contributed by the deposition to the building envelope and deposition in the building cracks. The building removal rate varies with particle size, and is more affected by wind direction than the air intake location for the building air handling system. The resulting indoor PM concentration, estimated via multizone modeling, varies with particle size and zone, and is affected by the alignment of building crack openings and wind direction. The demonstrated simulation method can be used to investigate the reduction of a pollutant plume by high-density building clusters in the urban environment as well as the human exposure to the plume indoors. As compared to well-mixed models, the CFD generated spatially-resolved pollutant concentration around the building improves the accuracy of the prediction of indoor exposure to outdoor PM plumes.