For some years, California has regulated the content of sulfur in gasoline, allowing just 10 parts of sulfur per million parts total (ppm). The rest of the country follows more generous requirements of 30 ppm. However, the Obama Administration is proposing to bring the national limits in line with those of California. Automakers and environmentalists joined forces in supporting the proposal, stating that lower sulfur content can improve the efficiency of catalytic converters in vehicles, which in turn further reduce the amount of harmful particulates exiting exhaust pipes. However, oil companies and Congressmembers from oil-producing states are against the change, claiming that the health benefits are minimal.