SRL for [pollute]: At the same time , moves toward tighter air - quality standards are spurring interest in lighter or alternative fuels that do n't [pollute] as much as fuel refined from `` heavy '' crudes , generally high in sulfur .
ARG-0: lighter or alternative fuels | R-ARG-0: that | ARG-M-NEG: n't | ARG-M-ADV: as much as fuel refined from `` heavy '' crudes , generally high in sulfur