Smog hanging over cities is the
most familiar and obvious form of air pollution we see today. Air pollution is
the introduction of particulates, biological molecules, or other harmful substances
such as harmful gases, dust ,smoke etc. into earth’s atmosphere, causing
diseases ,allergies, deaths, damages to living organisms, food and crops. As
the air becomes dirty, survival of plants, animals and humans become difficult.
Air pollution may come from man –made or natural sources. Air pollution refers
to the contamination of air irrespective of indoors or outdoors. It is physical,
biological or chemical altercation to the air in the atmosphere. The pollution
can be either visible or invisible or both, that contribute to global warming.
Another way of looking at air
pollution could be any substance that holds the potential to hinder the
atmosphere or the well-being of the living beings surviving in it. The
atmosphere is a complex natural gaseous system that is essential to support
life on planet earth. The sustainment of all living things is due to a
combination of gases that collectively form the atmosphere; the imbalance
caused by increase or decrease of these gases can be harmful for survival. Some
of the major air pollutants can be as follows:
Carbon Dioxide: Due to
human activities, the atmospheric concentration of carbon dioxide has been
rising extensively since the industrial revolution and has now reached
dangerous levels not seen in the last 3 million years. Human sources of carbon
dioxide emissions are much smaller than natural emissions but they have upset
the natural balance that existed for many thousands of years before the
influence of humans.
Carbon Monoxide: CO levels rise
quickly due to appliance malfunction i.e. , the heat exchanger or furnace
cracks, vent ,flue, or chimney is blocked by debris or even snow, fireplace, wood
burning stove, charcoal grill or other source of burning material that is not
properly vented. Several appliances running at the same time and competing for
limited fresh air can be a cause of CO build-up. Some other common pollutants
can be sulphur dioxide, nitrogen oxide, CFCs and ammonia.
Some lesser known and talked
about pollutants to be worried are as follows:
Volatile Organic Compounds (VOCs)
are outdoor air pollutants. They are categorized as methane or non-methane (NMVOCs).
Methane as we all know is a greenhouse gas and contributes to global warming.
The aromatic NMVOCs benzene, toluene and xylene are suspected carcinogens and
may lead to leukaemia with prolonged exposure.
Ground Level Ozone formed
from NO2 and VOCs, is a key constituent of the troposphere. At
abnormally high concentrations brought about by human activities, it is a
pollutant, and a constituent of smog.
Particulate Matter or the
particulates or fine particles are tiny particles of solid or liquid suspended
in a gas. Averaged worldwide, anthropogenic aerosols, those made by human
activities, currently account for 10 per cent of our atmosphere. Increased
levels of fine particles in the air are linked to health hazards such as heart
diseases, altered lung function and cancer.
Persistent Organic Pollutants
are organic compounds that are resistant to environmental degradation through
chemical, biological, and photolytic processes. Their accumulation and bio-magnification
in food chains is extremely harmful for humans.
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