Some day our descendants will marvel that we ever lived in cities filled with emissions direct from the tailpipes of cars. A new study from MIT suggests that in the US, 53,000 people a year die prematurely because of automobile pollution, compared to 34,000 people a year who die in traffic accidents.

These results more than double the number of people who die in the US every year as a result of automobiles, to nearly 100,000.

One in five Americans is in danger from air pollution, and it appears that the hazard is primarily their proximity to roadways. The most threatening kind of air pollution is fine particles, and automobiles represent only 7% of this kind of air pollution in the US. Power plants produce much more. But because cities are so saturated with tailpipe emissions, cars have a disproportionate impact on people’s health.

Air pollution has been implicated in low birth weight (and subsequent health problems and premature death), 430,000 premature deaths per year in Europe, and 4,655 premature deaths in São Paulo in 2011. Emissions from cars are a major cause of Beijing’s infamous smog.