Replacing the average diesel bus would generate a benefit of $84,200 per bus, split nearly evenly between health and climate effects. Such a replacement would cut 181 metric tons of carbon dioxide emissions per bus and reduce childhood deaths and asthma cases from diesel emissions, the researchers conclude.
The paper is here
Those numbers are colossally lower than what NYC and London came up with for transit buses ages ago (about $1.2 million/£1.7 million). I haven’t looked at the article yet but it’s probably due to the lower use and lower population density.
School busses are running fewer hours than transit busses, so that may account for the discrepancy.