On Friday, the Environmental Protection Agency finally proposed a new set of regulations – known as Tier 3 Vehicle Standards. The rules would reduce the amount of sulfur present in gasoline before our cars burn it. It brings the rest of the country in line with the environmental standards that have regulated California’s automobile industry for years.

Cutting back on the use of sulfur in gasoline by two thirds will have indirect environmental and public health benefits. While sulfur dioxide is not itself a greenhouse gas, reducing the amount of sulfur in gasoline will increase the efficiency of catalytic converters, reducing emissions and gasoline consumption. (Video explanation of how catalytic converters pull pollutants out of engine exhaust before it hits the air.)

When catalytic converters aren’t doing their jobs well, then they are emitting more pollutants like smog, nitrogen oxides, volatile organic compounds, particulate matter, and carbon monoxide. As the EPA puts it:

‘The proposed gasoline sulfur standard would make emission control systems more effective for both existing and new vehicles, and would enable more stringent vehicle emissions standards. Removing sulfur allows the vehicle’s catalyst to work more efficiently. Lower sulfur gasoline also facilitates the development of some lower-cost […]