New EPA regulations unveiled last week will go a long way toward improving U.S. air quality.
The EPA's Tier 3 rules both tighten vehicle emission standards and require refiners to reduce the amount of sulfur in gasoline by two-thirds. The rules take effect in 2017 and will affect the 2018-25 model years.
The oil industry has opposed Tier 3, protesting that costs outweigh benefits. Automakers support the rules, partly because EPA and California standards will be harmonized, eliminating the need to develop and certify two types of autos.
The EPA estimates automaker equipment costs at $72 per vehicle and the added gasoline cost at two-thirds of a cent per gallon. Refiners say their expenses are higher.
This is an important stage in the country's long climb toward cleaner air. The United States has made great progress from the smog-choked cities of the 1970s. The auto industry has a responsibility to make sure that progress continues.
Americans demand cleaner air, so it is in the transportation industry's self-interest to take a leadership role in the drive. But technology has reached the law of diminishing returns. Each new improvement costs more to achieve.
As the EPA recognizes, low-sulfur gasoline makes emission controls work better. It's more effective to remove sulfur from gasoline before combustion than to scrub sulfur compounds from the tailpipe afterward.
So the oil industry must do its part. Big Oil needs to be energetic in implementing Tier 3 standards.