 Unlike petrol engines, modern diesel engines are fitted with diesel particulate filters that help to reduce PM 10 and PM 2.5 emissions.However, those filters tend to get clogged easily with soot and are often removed by car owners.High levels of sulfur in diesel are harmful for the environment because they prevent the use of catalytic diesel particulate filters to control diesel particulate emissions, as well as more advanced technologies, such as nitrogen oxide (NOx) adsorbers (still under development), to reduce emissions.