The Sensitivity of the Annual Emissions Estimations of VOC, CO, NOX, SO2, NH3, PM2.5, and CO2 from On-road Mobile Sources by Using Annual Average versus Monthly Values of Temperature, Absolute Humidity, and Fuel RVP.

摘要

Annual on-road mobile source emissions must be updated every three years according to the U.S. Environmental Protection Agency (EPA). To estimate annual emissions, it is possible to use either annual average inputs or monthly input values of temperature, absolute humidity, and fuel Reid Vapor Pressure (RVP). The EPA's computer model, MOBILE6.2 (6.2.01) was used to estimate mobile source emissions. The latest available traffic data for the year 2002 obtained from the Tennessee Department of Transportation (TDOT) were used. This data included the estimates of vehicle speeds, truck mix, and vehicle miles of travel, by county and roadway type. Monthly average values of min/max temperatures, absolute humidity, and fuel RVP were used to obtain monthly and annual emissions. Annual emissions from monthly estimates were compared to emissions estimated by using annual average inputs of temperature, absolute humidity, and fuel RVP values. The findings were that it is important to use monthly average values of temperature, humidity, and fuel RVP to accurately estimate annual emissions for VOC and CO. No significant differences were calculated in annual emissions for NOX, SO2, NH3, PM2.5, PM10, and CO2 between the two methods. Monthly variations in Vehicle Miles Traveled (VMT) in Tennessee affect all emission estimates with the highest VMT occurring in July and the lowest in January. Monthly variations in temperatures and fuel RVP values significantly affect VOC and CO emissions. This study found that estimating annual emissions using monthly inputs is important for the pollutants, VOC and CO. This is a different conclusion from the previous research on mobile source emissions in Florida. Monthly emission variations were also investigated. It was found that emission factors of VOC and CO are dependent on temperature and RVP values. Humidity and temperatures are the most important factors affecting NOX emissions.