What is diesel soot?
Complex directly emitted carbon-core particles – commonly referred to as “soot” (illustrated below) form as a fresh byproduct of diesel combustion and are released at street level where people breathe them. Other secondary particles such as organics, sulfates and nitrates form from exhaust gases such as hydrocarbons, sulfur dioxide and nitrogen oxides, respectively. Directlyemitted particles typically have a carbon core coated with a variety of hazardous substances such as metals, toxics and organic compounds. Fresh diesel exhaust contains ‘ultrafine’ particles that are so small they can directly enter the bloodstream from the lung. Ultrafine particles begin right away to combine to form larger fine particles (PM 2.5) quite near the emissions source.
