Reducing School Bus Emissions in Texas

School bus emissions are of particular concern, not only for their contribution to overall air quality problems, but also for their impact on children, who are highly vulnerable to this health risk. The purpose of this study was threefold: to develop a methodology to estimate the emissions from school buses in nonattainment (NA) and early action compact (EAC) areas in Texas, perform an order of magnitude estimate of school bus emissions, and develop recommendations for reducing such emissions. Information about school bus fleets was obtained from 65 out of 228 school districts in the NA and EAC areas in Texas. By combining this data with an array of demographic data, such as school district location, population, minority population, and median household income, a model was developed to estimate the number of buses per category per school district. The study results indicate that school buses in the NA and EAC areas in Texas produce more than 2,400 tons of nitrogen oxides (NOx) emissions and almost 150 tons of particulate matter (PM 2.5) emissions per year. Although these emissions represent only 0.8% and 3.1% of the total NOx and PM 2.5 mobile source emissions, respectively, reducing these emissions is important because it can help NA areas reach attainment and reduce health risks to children. Furthermore, school bus emissions can be reduced by using strategies such as engine retrofitting or replacement, replacement of buses with new clean-burning units, and using cleaner fuels.