Diesel Exhaust What is Diesel Exhaust? The diesel engines in automobiles, buses, and trucks produce exhaust from the combustion of diesel fuel. Diesel exhaust is made up of harmful chemicals including very small toxic particles and hazardous gases. Some of the hazardous gases in diesel exhaust (e.g. nitrogen oxides, benzene, sulfur dioxide and formaldehyde) have been found to possibly cause cancer. Health Hazards of Diesel Exhaust Breathing diesel exhaust is the most common method of exposure. As we breathe, the fine particles and toxic gases in diesel exhaust can enter into the lungs. Being exposed to diesel exhaust for short periods of time may...