The researchers primarily attributed the reduced deaths to tougher federal regulations over the period, particularly the Clean Air Act and the 2002 NOx State Implementations Call. They also singled out rules specifically targeting vehicle emissions. These policy changes had enough impact to overcome surges in population, electricity demand and commute lengths, the researchers said.
The team suggested that further improvements, such as the 2011 Cross-State Air Pollution Rule, have likely contributed to further improvements since 2010. They intended to study pollution-related deaths since 2010 using other forms of data.
Whether or not pollution levels keep falling is another story. The researchers are concerned the current US government’s anti-science stance and deregulatory policies may slow or even reverse progress on air quality. At the same time, technology isn’t standing still. Increased adoption of clean energy, electric cars and hybrid vehicles could help, as could reduced car ownership.