Here is some information on sulfur dioxide.  The figures below are found on pps 11&12 in the photocopied class notes.

Sulfur dioxide is produced by the combustion of sulfur containing fuels such as coal.  Combustion of fuel also produces carbon dioxide and carbon monoxide.  People probably first became aware of sulfur dioxide because it has an unpleasant smell.  Carbon dioxide and carbon monoxide are odorless.

Volcanoes are a natural source of sulfur dioxide.

The Great London smog is still the deadliest air pollution event in history.  Because the atmosphere was stable, SO₂ emitted into air at ground level couldn't mix with cleaner air above.  The SO₂ concentration was able to build to dangerous levels.  You'll find the Donora, PA, disaster described in more detail on p. 335 in the text.

London type smog which contains sulfur dioxide and is most common during the winter is very different from photochemical or Los Angeles type smog.  Los Angeles type smog contains ozone and is most common in the summer.


Acid rain often falls hundreds or thousands of miles away from the source of the SO₂.  Coal fired factories and electric power plants in the Ohio River Valley could produce acid rain in New England and Canada.  Acid rain in Scandinavia could be the result of SO₂ emissions in England and Belgium.  Oxides of nitrogen (NO, NO₂, and N₂O) also react in clouds to form acid rain (nitric acid).



Among other things, acid rain has slowly been destroying stone buildings, statues and monuments.  The acid rain changes the relatively durable limestone or marble to gypsum which is more readily dissolved and washed away by rain.