New York City’s air quality has consistently been among the worst in the US. The city has the highest asthma mortality rate in the country. In July 2005, Mayor Bloomberg signed the Clean Air Taxis Act, allowing the use of hybrid electric vehicles as taxi cabs. According to the Sierra Club, this could reduce emissions of global warming pollutants by up to 50%. If the program is successful, NYC officials hope to have an entire green fleet in 8-10 years. The city has also been replacing its old diesel buses with hybrids and natural gas vehicles. They plan to expand the use of biodiesel for its heavy vehicles, such as sanitation trucks. So next time you’re in the Big Apple, hail a hybrid.