Atmospheric Environment: X (Oct 2022)
Modeling county-level benzene emissions using transportation analysis zones in the Denver metro area
Abstract
The link between exposure to benzene (an important toxic air pollutant) and physical health is well-documented as benzene is a known carcinogen. Understanding benzene concentration distributions in urban areas is very important and can be done using air dispersion models. An essential input requirement for dispersion models is the spatial and temporal allocation of emissions. Since most county-level benzene emissions come from gasoline powered motor vehicles, the goal of this work was to develop a new method of county-level benzene emission allocation using transportation analysis zones (TAZs) commonly used in travel demand models. The high spatial resolution provided by the TAZ allocation method helped visualize different flux patterns generated from five emission sectors and identified where more effort is needed to reduce benzene concentrations. The new allocation method was also tested using the AERMOD dispersion model to estimate benzene concentrations in the Denver metropolitan area. The model performance was assessed using 2014 morning benzene measurements from a monitoring station located in downtown Denver; results showed an acceptable model-to-monitor ratio. The model was also used to investigate the effect of temperature inversions on morning benzene concentrations. As expected, predicted benzene concentrations were higher during temperature inversions and model-to-monitor ratios during investigated days were within a factor of two. The TAZ allocation modeling methodology demonstrated in this work can improve the estimation of air pollution exposure in future health-related studies.
