What is diesel exhaust?
Diesel exhaust is a complex mixture of toxic compounds including the termed "carcinogen" Diesel Particulate Matter (DPM), commonly termed "soot". Diesel exhaust also contains certain Nitrogen Oxides (NOx), Polyaromatic Hydrocarbons (PNAs), Sulfur Dioxide (SO2), and Carbon Monoxide (CO). Some DPM (soot) particles are large or dark enough to be seen as soot or smoke. Others are so small that several thousand of them could fit on the period at the end of this sentence. The smallest diesel particles are diameters below 50 nanometers (a nanometer is one million times smaller than the head of a pin). Newer diesel engines emit higher numbers of small particles than the older vehicles. Research has shown that the smallest diesel particles are of the greatest health concern as they will penetrate deep into sensitive areas of the respiratory tract.
