Daily exposure to low levels of CO is linked with lack of fitness, a tendency to form blood clots, and disease of the heart, arteries and lungs. At concentrations above 200 ppm, exposure to CO for more than a few minutes is fatal. Sulfur dioxide is an acrid-smelling gas that even at low concentrations irritates the membranes of the nose and respiratory system. It is thought to exacerbate many respiratory diseases, including asthma. Sulfur dioxide is produced whenever sulfur-containing compounds are burnt.
Oil is made up of sulfur and other naturally occurring elements.
Burning oil releases these elements. Sulfur Dioxide and oxides of Nitrogen react together with water vapour to create acid rain. Sulfate particles are also produced naturally from gases emitted by marine organisms. Industry and motor vehicles add significantly to the concentration of particles in the atmosphere - high concentrations are found in big cities and industrial areas. These particles remain airborne for long periods, lowering visibility.