Diesel locomotive were classified as DET 1 and DET 2 (). Due to shortage of petrol products during World War I, they remained unused for regular service in Germany. In 1922, they were sold to Swiss Compagnie du Chemin de fer Régional du Val-de-Travers (), where they were used in regular service up to the electrification of the line in 1944. Afterwards, the company kept them in service as boosters till 1965. Fiat claims a first Italian diesel–electric locomotive built in 1922, but little detail is available. A Fiat-TIBB diesel–locomotive "A", of 440CV, is reported to have entered service on the Ferrovie
Diesel locomotive use of biodiesel). Diesel locomotive pollution has been of particular concern in the city of Chicago. The "Chicago Tribune" reported levels of diesel soot inside locomotives leaving Chicago at levels hundreds of times above what is normally found on streets outside. Residents of several neighborhoods are most likely exposed to diesel emissions at levels several times higher than the national average for urban areas. In 2008, the United States Environmental Protection Agency (EPA) mandated regulations requiring all new or refurbished diesel locomotives to meet Tier II pollution standards that slash the amount of allowable soot by 90% and require an