Air pollution consists of chemicals or particles in the air that can harm the health of humans, animals, and plants. It also damages buildings. Pollutants in the air take many forms. They can be gases, solid particles, or liquid droplets.
Sources of Air Pollution
Pollution enters the Earth's atmosphere in
many different ways. Most air pollution is created by people, taking
the form of emissions from
factories, cars, planes, or aerosol cans.
Second-hand cigarette smoke is also considered air
pollution. These man-made sources
of pollution are called anthropogenic sources.
Some types of air pollution, such as smoke from wildfires or ash from volcanoes, occur naturally. These are called natural sources.
Air pollution is most common in large cities where emissions from
many different sources are concentrated.
Sometimes, mountains or tall
buildings prevent air pollution from spreading out. This air
pollution often appears as a cloud making the air murky. It is
called smog. The word "smog"
comes from combining the words "smoke" and "fog."
Large cities in poor and developing nations tend to have more air
pollution than cities in developed nations. According to the World Health Organization (WHO), some of the worlds
most polluted cities are Karachi, Pakistan; New Delhi, India; Beijing, China;
Lima, Peru; and Cairo, Egypt. However, many developed nations also
have air pollution problems. Los Angeles, California, is
nicknamed Smog City.
Indoor Air Pollution
Air pollution is usually thought of as smoke from large
factories or exhaust from vehicles.
But there are many types of indoor air pollution as well.
Heating a house by burning substances such as kerosene,
wood, and coal can contaminate the air inside the house. Ash
and smoke make breathing difficult, and they can stick to walls,
food, and clothing.
Naturally-occurring radon gas,
a cancer-causing material, can also
build up in homes. Radon is released through the surface of the
Earth. Inexpensive systems installed by professionals can reduce radon levels.
Some construction materials, including insulation,
are also dangerous to people's health. In addition, ventilation, or air movement, in homes and rooms
can lead to the spread of toxic mold. A
single colony of mold may exist in a damp, cool place in a
house, such as between walls. The mold's spores enter
the air and spread throughout the house. People can become sick from breathing
in the spores.
Effects On Humans
People experience a wide range of health effects from being exposed to air
pollution. Effects can be broken down into short-term
effects and long-term effects.
Short-term effects, which are temporary,
include illnesses such as pneumonia or bronchitis.
They also include discomfort such as irritation to
the nose, throat, eyes, or skin. Air pollution can also cause
headaches, dizziness, and nausea. Bad
smells made by factories, garbage,
or sewer systems are considered air
pollution, too. These odors are
less serious but still unpleasant.
Long-term effects of air pollution can last for years or for an
entire lifetime. They can even lead to a person's death. Long-term health
effects from air pollution include heart
disease, lung cancer,
and respiratory diseases such
as emphysema. Air
pollution can also cause long-term damage to people's nerves, brain, kidneys, liver, and other organs. Some scientists suspect
air pollutants cause birth defects.
Nearly 2.5 million people die worldwide each year from the effects of outdoor
or indoor air pollution.
People react differently to different types of air pollution. Young
children and older adults, whose immune systems tend
to be weaker, are often more sensitive to pollution. Conditions such as asthma, heart disease,
and lung disease can be made worse by exposure to air pollution.
The length of exposure and amount and type of pollutants are also
factors.
Effects On The Environment
Like people, animals, and plants, entire ecosystems can
suffer effects from air pollution. Haze,
like smog, is a visible type of air pollution that obscures shapes and colors. Hazy air
pollution can even muffle sounds.
Air pollution particles eventually fall back to Earth. Air
pollution can directly contaminate the surface of bodies of
water and soil. This can kill crops or reduce their yield. It can kill young trees and other plants.
Sulfur dioxide and nitrogen oxide particles in the air, can
create acid rain when they mix with
water and oxygen in
the atmosphere. These air pollutants come mostly from coal-fired power plants and motor vehicles. When acid rain falls to
Earth, it damages plants by changing soil
composition; degrades water
quality in rivers, lakes and streams; damages crops; and can cause
buildings and monuments to decay.
Like humans, animals can suffer health effects from exposure to air
pollution. Birth defects, diseases, and lower reproductive rates have all been attributed to air pollution.
Global Warming
Global warming is an environmental phenomenon caused
by natural and anthropogenic air pollution. It refers to rising air and
ocean temperatures around the world.
This temperature rise is at least partially caused by an increase in
the amount of greenhouse gases in
the atmosphere. Greenhouse gases trap heat energy in the
Earths atmosphere. (Usually, more of Earths heat escapes into space.)
Carbon dioxide is
a greenhouse gas that has had the biggest effect on global
warming. Carbon dioxide is emitted into
the atmosphere by burning fossil
fuels (coal, gasoline,
and natural gas). Humans have come
to rely on fossil
fuels to power cars and planes, heat homes, and run factories. Doing these
things pollutes the air with carbon dioxide.
Other greenhouse gases emitted by natural and artificial
sources also include methane, nitrous oxide, and fluorinated gases. Methane is
a major emission from coal plants and agricultural
processes. Nitrous oxide is a common emission from
industrial factories, agriculture, and the burning of fossil fuels in
cars. Fluorinated gases, such as hydrofluorocarbons,
are emitted by industry. Fluorinated gases are often
used instead of gases such as chlorofluorocarbons (CFCs). CFCs have
been outlawed in many places because they deplete the ozone layer.
Worldwide, many countries have taken steps to reduce or
limit greenhouse gas emissions to combat global warming. The Kyoto Protocol, first adopted in Kyoto, Japan, in
1997, is an agreement between 183 countries that they will work
to reduce their carbon dioxide emissions. The United States
has not signed that treaty.
Regulation
In addition to the international Kyoto Protocol, most developed nations
have adopted laws to regulate emissions and reduce air
pollution. In the United States, debate is under way about a system
called cap and trade to
limit emissions. This system would cap, or place a limit, on the amount of
pollution a company is allowed. Companies that exceeded their
cap would have to pay. Companies that polluted less than their cap could trade
or sell their remaining pollution allowance to other companies. Cap and
trade would essentially pay companies to limit pollution.
In 2006 the World Health Organization issued new Air Quality Guidelines. The
WHOs guidelines are tougher than most individual countries existing guidelines.
The WHO guidelines aim to reduce air pollution-related deaths by 15
percent a year.
Reduction
Anybody can take steps to reduce air pollution. Millions of people
every day make simple changes in their lives to do this. Taking public transportation instead of driving a
car, or riding a bike instead of traveling in carbon
dioxide-emitting vehicles are a couple of ways to reduce air
pollution. Avoiding aerosol cans, recycling yard trimmings instead of burning them, and
not smoking cigarettes are others.
标签:air,also,effects,such,Air,pollution From: https://www.cnblogs.com/Lookingsky233/p/17808344.html