Global Harmonization in the Regulation of Vehicle Exhaust Emissions

Japan’s vehicle exhaust emissions regulations have always been among the world’s most stringent, and its automakers have worked very hard to develop the advanced technologies required to comply with them. As a result, NOx and other atmospheric pollutant levels have been, even in large urban areas, on a steady decline. Japan has participated in international discussions on the global harmonization of emission test cycles and in 2010 introduced the UN test cycle for motorcycle emissions. In 2018 Japan adopted the UN “WLTC” to measure emissions from new gasoline-powered passenger cars and light commercial vehicles, following its adoption in 2016 of the UN “WHTC” for measuring diesel exhaust emissions from new heavy-duty vehicles (see corresponding notes below).