Here are a few things you should probably know about sulfur
dioxide.
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. 4000 people
died during this 4 or 5 day period. As many as 8000 additional
people died in the weeks and months following the December event.
The sulfur dioxide didn't
kill people directly. The SO2 aggravated an existing
condition of some kind and hastened their
death. The SO2 probably also made people susceptible to bacterial
infections such as pneumonia. This
link discusses the event and its health effects in more detail.
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.
Some other air pollution disaster also involved high SO2
concentrations. The Donora Pennsylvania event is described on p.
346 in the textbook.
"This eerie photograph was taken at noon on Oct.
29, 1948 in Donora, PA as deadly smog enveloped the town. 20 people
were asphyxiated and more than 7,000 became seriously ill during this
horrible event."
from: http://oceanservice.noaa.gov/education/kits/pollution/02history.html
