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Sulfur Compounds
Burning coal and gasoline
Can kill plants and fish.
Eats away at metal, stone,
plastic, rubber
Carbon Monoxide
More than 80% from car
exhausts
Nausea, dizziness, drowsiness,
even death
Carbon Dioxide
Burning coal : gasoline, gas,
wood
Too much can harm and cause
Earth’s atmosphere and
ground to warm up
Nitrogen Compounds
Power plants, autos, diesel
engines, home furnaces
Forms nitric acid and results in
acid rain
Hydrocarbons
Auto and plane engines
Lung cancer
Industrial pollution comes from the burning of coal, oil, etc.
The black smoke you see reaching into the air from the chimneys of most industries is made of
two basic chemical compounds known as sulphur dioxide (So2) and nitrogen oxides (NO).
These two compounds are transformed into other compounds when they are in contact with the
sun rays and the water in the air (water in the air takes the form of clouds or the evaporation of
water coming from seas and plants).
This is called a Chemical Reaction.
What is a Chemical Reaction?
Imagine you want to bake a bread. You will need separate and very different elements such as
water, maybe eggs, flour and yeast. As you mix the elements together, you cannot recognize
anymore the eggs from the flour, and the water makes the mixture become like a smooth ball to
form the dough. Add some yeast and a chemical reaction happens. How do you know it is a
chemical reaction? You know it because the dough rises; some kind of magic happens,
something you could not obtain without the yeast!
In the pollution process, a very different chemical reaction occurs.
SO2 and NOx become something else when mixed with the sun rays and the water present in the
clouds or the atmosphere.
Oxidation means that some parts of the product will be detached and recomposed differently.
Have you ever seen a metal rusting? This is an oxidation; the oxidation is caused by a chemical
reaction. The bright metal becomes red in contact for a certain time with water and the air.
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See, in the figure below, SO2 and NO oxide. The elements obtained by oxidation are dissolved.
Do you know what the word dissolution means?
Put a lump of sugar in a glass of water, then watch. What happens? The sugar disappears and the
water tastes of sugar, right? This is called a dissolution.
It is pointless at this stage to explain all these chemical reactions. The most important thing to
remember is that some dangerous chemical elements are dissolved into the atmosphere and fall
into the earth. This is called the Acid Rain because SO and NO are transformed into acids. We
will see later what the word acid means.
Picture courtesy of: http://royal.okanagan.bc.ca/mpidwirn/atmosphereandclimate/acidprecip.html#a
60-70 % of the acid deposition coming from emissions of sulphur dioxide (So2) is from
human origin.
The sulphur dioxide is obtained from coal burning, by smelting metals, volcanic eruptions adding
to a local problems, and organic decay.
In Europe, emissions of SO2 have been well reduced, about 40% in 20 years.
In Western Europe, emissions are almost 50% lower now than in 1980.
The reasons are the economic decline followed by the closure of factories, and the introduction of
new technology to clean up emissions.
When in the air, sulphur dioxide can land on the Earth's surface in the form of dry dust, or it can
be turned into acid by a chemical reaction in contact with the moist air (H2O).
What do the transcriptions So and NO mean?
They are the symbols of two basic elements in our natural world.
For example, plants release Oxygen that we breathe in order to ventilate our lungs and stay alive.
Oxygen’s symbol is O. We release Carbon Dioxide from our lungs into the air; this Carbon
Dioxide is inhaled by plants who need it to live. The Carbon’ symbol is CO2. The symbol of
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