Motorcycles and gas-powered recreational boats could become substantially cleaner if emissions cuts proposed by the Bush administration late last week are enacted. The proposals call for halving emissions from motorcycles (which are, on average, 20 times more polluting per mile than a new car) and reducing boat emissions by 80 percent. The new standards would take effect in 2006 and 2008, respectively. Currently, motorcycles and boats account for 12 percent of hydrocarbon emissions and 3 percent of carbon monoxide emissions from mobile sources. According to U.S. EPA Administrator Christie Whitman, the new standards would have clean air gains equivalent to reducing pollution from 9.4 million cars per year. Environmentalists praised the move as a step in the right direction, but had been hoping to see emissions cuts for motorcycles of up to 90 percent.