Carbon particles, in the form of soot, are the major component of diesel exhaust. These particles can cause respiratory problems after prolonged exposure as they can build up in the lungs. While carbon itself is not toxic, it can clog the lungs and impair respiratory function.
Tiny particles of sulfur dioxide are borne into the atmosphere by air currents where they can gradually make their way to higher altitudes and become suspended in clouds where they mix with water vapor to make sulfuric acid. This process is the basis for the formation of acid rain, which can damage buildings and other structures as well as upset ecological balances by changing the pH of bodies of standing water and ground water.
Heavy metals such as mercury, lead and manganese are also found in diesel exhaust. Mercury and lead are very dangerous and build up in organic tissues over time; continued exposure leads to higher concentrations of these metals in the body and can cause serious health problems.
Organic toxic compounds like cyanide, phenol, formaldehyde and acetaldehyde are also present in diesel exhaust.
Carbon monoxide is a by-product of the combustion of many petroleum fuels. It is colorless, odorless and highly toxic. Over-exposure to carbon monoxide can cause breathing problems, lethargy, unconsciousness and, in high concentrations, death.
