Nearly one half of all Americans—an estimated 150 million—live in areas that don’t meet federal air quality standards. Passenger vehicles and heavy-duty trucks are the main sources of this pollution, which includes ozone, particulate matter, and other smog-forming emissions.
The health risks of air pollution are extremely serious. Poor air quality increases respiratory ailments like asthma and bronchitis, heightens the risk of life-threatening conditions like cancer, and burdens our health care system with substantial medical costs. Particulate matter—the soot and metals that give smog its murky color—is singlehandedly responsible for up to 30,000 premature deaths each year.
Passenger vehicles are a major pollution contributor, producing significant amounts of nitrogen oxides, carbon monoxide, and other pollution. And despite only accounting for 7 percent of all vehicles, heavy-duty trucks like semis and school buses produce nearly 25 percent of all smog-forming pollution.