Major ions in PM 2.5 and PM 10 released from buses: The use of diesel/biodiesel fuels under real conditions

•The use of fuel blend 95% petro diesel and 5% biodiesel by the heavy duty vehicles.•Emissions profile of major ions from the combustion of biodiesel blend in real conditions.•Low-molecular weight carboxylate and water-soluble inorganic ions.•Chemical reactions occurred during fuel combustion until formation of carboxylate anions.•Atmospheric transformations of engine exhausts, vehicular emissions, and their contribution to general air pollution.