Sulphur
dioxide
By Sarah Connolly (Y11 TA Loreto
Oct 2002)
Sulphur dioxide is a
respiratory irritant and a choking, acidic gas. It is colourless but smelly. It dissolves in
water to form sulphurous acid, which is weaker than sulphuric acid.
It
forms when fossil fuels are burnt as sulphur is present in all living things.
Fossil fuels are made from decayed plants and animals. When these are burnt the sulphur
reacts with the oxygen in the air to form sulphur dioxide.
S + O2 = SO2
SO2 + H2O = H2SO3
Note
that sulphurous acid (H2SO3)
will subsequently oxidise
to form sulphuric acid (H2SO4).
The main producers of sulphur dioxide are power stations and chemical industry. Copper and lead smelting industries are particularly bad since they extract the metals from the SULPHIDE ores called Copper and Lead Pyrites .
Click her to see how SO2 level have risen.
Please click here to see a pie chart for sources of SO2 in one area of the USA.
Click
here to see SO2
levels of Great Britain and Ireland.
Note that the
lighter the blue, moving to green, the worse the problem.
Click here to see Levels of SO2 in different UK cites compared.
Click
here to see "SO2
hot-spots in Industrial Northern England"
Note that red is 6-8 times worse than dark blue.
Now click here to see SO2 level in N. Ireland.
Click
here to see average SO2
levels over Europe between 15-29 February 1996.
Note here that enhanced SO2
levels observed in Eastern Europe are most likely emissions from coal power
plants.
During this period (February) surface temperatures were extremely low, so that
private household
may also have contributed to the high SO2
values
Click her to see sources of SO2 in the USA in 1992.
Click here to spot the heavy industrial areas of the USA.
The breakdown of major SO2 emitting sources in one industrial area of the USA (Dayton, Ohio) was found to be as follows: utilities 69.5%; industrial manufacturing processes 12.7%; industrial combustion 11.6%; transportation 3.7%, and other 2.5%. On a World-wide scale volcanoes produce very large amounts of the gas! Click here to see how SO2 emissions from St Helen's have varied over the years.
These problems, which affect a person's ability to breathe, have led to both increase sickness and deaths. Based on these concerns, SO2 has been regulated under the Clean Air Act. RAPCA has not observed ambient concentrations sufficient to induce these effects in it's six-county area.
Title IV of the 1990 Clean Air Act Amendments was implemented to achieve significant reductions in annual SO2 emissions. The primary goal was to reduce SO2 emissions by 10 million tons below 1980 levels using a two-phase approach. Phase I, which began in 1996, affects 110 coal burning electric utility plants located in 21 eastern and mid-western states. Phase II, which began in 2000, tightens the emissions on these large plants and puts into play restrictions on smaller plants fired by coal, oil, and gas.
Data for the period 1988 to 1997 is presented graphically below. Can you tell if the Clean Air Act has been working?
When sulphur
dioxide is inhaled, it causes tightening of the airways (trachea, bronchi, etc.)
and can therefore cause choking and violent coughing. People suffering from asthma are significantly more sensitive
to sulphur dioxide and relatively small amounts may well bring on an asthmatic
attack sometime after the exposure. Prolonged
exposure to sulphur dioxide can
cause damage to the air sacs in lungs and bring on emphysema, chronic bronchitis
and acute chest illnesses.
The
first diagram below shows how our airways look normally. They are open and relaxed.
The
next diagram shows how the airways change during
asthma. They are narrow, tight and swollen.
Click
here to visit a site with loads on Asthma.
Within
this page follow the link
Pathophysiology of Asthma Animation
for a short series of audio & animation clips on Asthma.
Another
Page to find animations of
both Allergic Reactions and Asthma
For more precise details on what SO2 does please click here.
The
Story of Ventolin. Used in treatment for Asthma.
By Brendan Colgan
another Loreto Pupil.
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to Main Page.
