Smoke produced by burning oil contains soot (carbon black), sulphur dioxide, carbon monoxide, nitrogen oxides, heavy metals and polycyclic aromatic hydrocarbons.
The smoke cloud produced by burning oil wells following the Gulf War produced a steep rise in the numbers of asthma suffers, and complaints such as severe eczema and eye irritation. Sheep and other grazing animals died from hydrocarbon-contaminated grass. The smoke was injected 5000 metres into the atmosphere. Smoke, black rain and black snow were reported over 3,500 kilometres away.