Researchers attributed the reduced deaths primarily to more stringent federal regulations, notably the Clean Air Act and the 2002 Notify State Implementations Call. They also selected rules that specifically target vehicle emissions. These policy changes would have been effective in overcoming population swings, electricity demand and commuting, researchers said.
The team suggested that further improvements, such as the 201
Whether the pollution continues to decline is another story. Researchers are concerned that the current US government's anti-science policy and deregulation policy may slow or even reverse air quality advances. At the same time, the technology does not stand still. Increased introduction of clean energy, electric cars and hybrid vehicles could help, as could the ownership of cars.