Ozone

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The Ozone

Our Earth’s atmosphere is divided into several layers. The lowest region, the
troposphere, extends from the Earth’s surface up to 10 kilometers in altitude. All human
activity occurs in the troposphere. The next layer, the stratosphere, continues from the
end of the troposphere to about 50km. Most air traffic occurs in the stratosphere.
Ozone is a tri-atomic allotrope of oxygen that accounts for the distinctive odor
after a thunderstorm or around electrical equipment. The odor of ozone around electrical
machines was reported as early as 1785, and ozone’s chemical make-up was determined
in 1872. Ozone is an irritating, pale blue gas that is explosive and toxic, even at low
concentrations. Ozone is 1.5 times as dense as oxygen. At -112 degrees Celsius, it
condenses into a dark blue liquid, which freezes at -412 degrees Celsius. Ozone is an
extremely powerful oxidizing agent. It is used commercially as a bleaching agent and as a
strong germicide used to sterilize drinking water as well as to remove objectional odors
and flavors.
Most atmospheric ozone is concentrated in the stratosphere, about 15-30km above
the Earth’s surface. Ozone is a molecule containing three oxygen atoms. The oxygen that
we breathe has only two oxygen atoms and no color or odor. Ozone occurs far less than
oxygen, of every ten million air molecules, two million are normal oxygen and only three
are ozone. The small amount of ozone plays an important role in the atmosphere. The
ozone layer absorbs radiation from the sun, preventing it from reaching Earth’s surface. It
more importantly absorbs UVB ultraviolet light. UVB causes skin cancer, cataracts, can
harm some kinds of farm plants, certain materials, and some forms of sea creatures.
At any given time ozone molecules are created and destroyed in the stratosphere.
The total amount of ozone stays at a stable level. The best way to describe it is to
compare a stream’...