关键词：汽车；清洁空气法案（CAA）；气候；环境保护署
摘 要：On February 18, 2014, President Obama directed the Environmental Protection Agency (EPA) and the National Highway Traffic Safety Administration (NHTSA) to develop a second round of greenhouse gas (GHG) emission and fuel economy standards for medium- and heavy-duty trucks. The standards, which will affect trucks beginning with the 2019 model year, are to be proposed by March 2015 and finalized a year later. The standards will be the fourth set of GHG emission standards for mobile sources.