? 1—What is Pollution? 14 Environmental Pathways
plants grow by using sunlight, water, and
the carbon dioxide gas that people and other
animals breathe out, and in turn they produce
the oxygen we need to breathe in. This
process is known as photosynthesis.
Without green plants all the oxygen in the air
would eventually be used up and the earth
would no longer be able to support life.
The Air We Breathe
No matter where you go or what you do,
there is something that you have in common
with every other living person. When you are
walking to school or eating lunch, whether you
are awake or asleep, you are doing it.You are
breathing.
Whether outside playing or in the classroom
learning, everyone has to breathe. In your life-time
you will breathe about 625,000,000
times. What will you be breathing? Air. Take
away your supply of air and you could live for
only a few minutes.
Air is one of our most valuable resources.
Clean air is a mixture of different gases, such
as nitrogen and oxygen, with small amounts
of water vapor, argon, carbon dioxide, neon,
helium and hydrogen. Unfortunately, there can
be pollution in the air we breathe. Air pollution
occurs when harmful things are present or
released into the air. These harmful things are
called pollutants and they come from many
sources.
School buses and your family’s car produce
emissions that can pollute the air. The facto-ries
that make things such as desks, books
and bicycles can also produce emissions that
go into the air. In fact, all over the world,
millions of vehicles and factories release air
pollutants. Still more of these pollutants come
from things that ordinary people do every day.
Here is a partial list of common things which
contribute directly to pollution in the air:
• Burning paper, plastic, leaves and trash
• Heating homes with wood, coal and oil
• Using air conditioners
• Smoking cigarettes, pipes and cigars
• Driving cars, trucks, motorcycles, air
planes and motor boats
• Using lighter fluid to start outdoor grills
All of these activities can pollute the air.
Sometimes you can smell the pollution, and
sometimes, when the air looks hazy or smoky,
you can see it. However, even air that looks
and smells clean can be polluted.
The Cycling of Materials
(Decomposition)
Wood, cotton and other materials produced
by living things are broken down into atoms
(simpler particles that are too small to be
seen) by microscopic plants and animals such
as bacteria and fungi.We call this process
decomposition. The atoms will combine to
become new substances or new living things.
This is nature’s way of recycling matter and
turning it from one form to another.
Decomposition is particularly important in
maintaining our soil.
The Land We Depend On
Soil, dirt, land—no matter what you call it, it’s
the material that makes up the top layer of the
Earth.We build our homes on it, we raise food
in it, we mine resources such as coal beneath
it, we bury our garbage in it.
THE PARTS OF NATURAL DRY AIR
21 %
oxygen
1%
other gasses
78%
nitrogen
Source: Turk & Turk, Environmental Science, 1984.
