In a perfect combustion, carbon dioxide, water and nitrogen are the end products. The incomplete combustion of diesel fuel results in emissions that include oxides of nitrogen (NOx), carbon monoxide (CO), Carbon dioxide (CO2), water (H2O) and unburned hydrocarbons (HC). There are also un-burnt carbon particles, as well as engine oils, debris, soot and ash particulates which are known as particulate matter (PM). This diesel particulate matter (DPM) is the visible cloud of black smoke that appears from the engine start-up and continues to appear when the engine is running. DPMS can be categorized into two groups.
Particles of 2.5 microns to 10 microns, and particles of less than 2.5 microns in size. More than 99% are in the sub 2.5 microns range. They are all damaging to your health.