A new study finds pollution has dropped in New York City and the surrounding areas since congestion pricing went into effect in Manhattan.  

The report found in the first six months of the program, air pollution dropped by 22% in the congestion zone below 60th Street. But it also found declines beyond that.

Tim Fraser is an assistant teaching professor at Cornell Systems Engineering at Cornell University. He spoke to WNYC's Morning Edition host Michael Hill about why this has implications not only for the region, but for the world.