California leads the way with groundbreaking emissions rules for trains and trucks.

California's Air Resources Board has approved a rule banning the use of locomotive engines more than 23 years old by 2030 and increasing the use of zero-emissions technology to transport freight from ports and throughout railyards. The rule would also ban locomotives in the state from idling longer than 30 minutes if they are equipped with an automatic shutoff. The rule would curb emissions on a class of engines that annually release more than 640 tons of tiny pollutants that can enter deep into a person's lungs and worsen asthma, and release nearly 30,000 tons of smog-forming emissions known as nitrogen oxides.