Carbon Monoxide - Carbon monoxide is a significantly toxic gas, but, being colorless, odorless, tasteless, and non-irritating, it is very difficult for people to detect. Exposures at 100 ppm can be life-threatening.
Nitrogen dioxide - a reddish-brown, highly poisonous gas, a prominent air pollutant
Sulphur dioxide - Since coal and petroleum often contain sulfur compounds, their combustion generates sulfur dioxide. Further oxidation of SO2, usually in the presence of a catalyst such as NO2, forms H2SO4, and thus acid rain. This is one of the causes for concern over the environmental impact of the use of these fuels as power sources.
Benzene - Links to leukemia
Formaldehyde - a colorless gas with a strong, suffocating odor.
Polycyclic hydrocarbons - PAHs are one of the most widespread organic pollutants. High prenatal exposure to PAH is associated with lower IQ.

