Delhi will become the first Indian city to make a complete switch to ultra low sulphur diesel (ULSD). The deadline for the switch has been fixed as April 1, 2010, which will be concurrent with the introduction of Euro IV compliant vehicles.
In ultra low sulphur diesel (ULSD), the sulphur content is one-seventh of what it is in diesel sold now. The diesel that is presently available has a sulphur content of 350 parts per million (ppm) where as the ULSD Delhi will be having only 50ppm sulphur. Though it is seven times cleaner than the diesel available now, but way too high for the international clean diesel standard of 15ppm.