Complex sentence: The results indicated a 32% reduction in unburned hydrocarbons and 26% reduction in particulate emissions (8), so a second phase was conducted using eight heavy-duty diesel vehicles during 1988-1989.
Split into simpler sentences: The results indicated a 32% reduction in unburned hydrocarbons and 26% reduction in particulate emissions (8). A second phase was conducted using eight heavy-duty diesel vehicles during 1988-1989.