WHAT IS AIR POLLUTION ?
Air pollution occurs when the air contains gases, dust, fumes or odour in harmful amounts. That is, amounts which could be harmful to the health or comfort of humans and animals or which could cause damage to plants and materials.
The substances that cause air pollution are called pollutants. Pollutants that are pumped into our atmosphere and directly pollute the air are called primary pollutants. Primary pollutant examples include carbon monoxide from car exhausts and sulfur dioxide from the combustion of coal.
Further pollution can arise if primary pollutants in the atmosphere undergo chemical reactions. The resulting compounds are called secondary pollutants. Photo chemical smog is an example of this.
HISTORICAL EXPLANATION
In the days before the proliferation of large cities and industry, nature's own systems kept the air fairly clean. Wind mixed and dispersed the gases, rain washed the dust and other easily dissolved substances to the ground and plants absorbed carbon dioxide and replaced it with oxygen.
With increasing urbanization and industrialization, humans started to release more wastes into the atmosphere than nature could cope with.
Since then, more pollution has been added to the air by industrial, commercial and domestic sources. As these sources are usually found in major cities, the gases that are produced are usually concentrated in the air around them. The adverse effects of air pollution were graphically illustrated in London in 1952 when, in just a few days, an estimated 4000 people died from effects of fine particle pollution.
It is when these concentrated gases exceed safe limits that we have a pollution problem. Nature can no longer manage air pollution without our help.
MORE ABOUT POLLUTANTS
Air pollutants mainly occur as a result of gaseous discharges from industry and motor vehicles. There are also natural sources such as wind-blown dust and smoke from fires.
Some forms of air pollution create global problems, such as upper atmosphere ozone depletion and global warming. These problems are very complex, and require international cooperative efforts to find solutions.
EXAMPLES OF AIR POLLUTANTS
There are two types of pollutants:
- Primary pollutants are those gases or particles that are pumped into the air to make it unclean. They include carbon monoxide from automobile (cars) exhausts and sulfur dioxide from the combustion of coal.
- Secondary pollutants: When pollutants in the air mix up in a chemical reaction, they form an even more dangerous chemical. Photo chemical smog is an example of this, and is a secondary pollutant.
CAUSES OF AIR POLLUTION
- What is the short term effect of the haze on my health?
Among healthy individuals, short term exposure (i.e.
continuous exposure to unhealthy daily average PSI levels over a period of a
few days) to high levels of haze particles may cause irritation of the eyes,
nose, and throat in healthy individuals. Such irritation resolves on its
own in most cases.
Haze particles can affect the heart and lungs, especially in
people who already have chronic heart or lung disease e.g. asthma, chronic
obstructive pulmonary disease (COPD), or heart failure.
There may be up to 1-3 days of time between exposure to haze
and health effects/ symptoms.
- What are the long term effects of the haze?
Singapore is not affected by the haze throughout the year.
Any exposure is short-term in nature (i.e. continuous exposure to unhealthy
daily average PSI levels over a period of a few days) and such exposure may
vary from year to year. As international studies are based on long term
exposure to air pollution, there is little robust data on the longer-term
effects of short-term exposure to haze like the pattern seen in Singapore.
Studies have shown that persons living overseas with
continuous exposure over several years to high ambient pollution from fine
particles (i.e. particulate matter 2.5 (PM2.5); particles smaller than 2.5
micrometers), may have a higher risk of (i) cardiovascular effects, such as
heart attacks, (ii) reduced lung development, as well as (iii) the development
of chronic respiratory diseases, such as asthma, in children.
EFFECT OF AIR POLLUTION
Chemical reactions involving air pollutants can create
acidic compounds which can cause harm to vegetation and buildings. Sometimes,
when an air pollutant, such as sulfuric acid combines with the water droplets
that make up clouds, the water droplets become acidic, forming acid rain. When
acid rain falls over an area, it can kill trees and harm animals, fish, and
other wildlife.
Acid rain destroys the leaves of plants.
Acid rain destroys the leaves of plants.
When acid rain infiltrates into soils, it changes the chemistry of the soil making it unfit for many living things that rely on soil as a habitat or for nutrition. Acid rain also changes the chemistry of the lakes and streams that the rainwater flows into, harming fish and other aquatic life. It also can cause haze which is happening in our country, because of air pollution.
Rain can carry and deposit the Nitrogen in some pollutants
on rivers and soils. This will adversely affect the nutrients in the soil and
water bodies. This can result in algae growth in lakes and water bodies, and make
conditions for other living organism harmful.
Chemical reactions involving air pollutants create a
poisonous gas ozone (O3). Gas Ozone can affect people’s health and can damage
vegetation types and some animal life too.
SOLUTION OF AIR POLLUTION
The most effective way to overcome the air pollution is by
using the public modes of transportation. The public transportation consists of
a variety of modes such as buses, commuter trains and so on. By using this
method, the exhaust from individual vehicles which contain carbon monoxide and
carbon dioxide can be reduced drastically. The carbon monoxide contain CO bond
which can reducing oxygen delivery to the organs of human’s body. Hence, it is
better for us to use the public transportation instead of individual vehicles.
Due to the modern technology nowadays, the public transportation which use the
newer diesel and electrically powered vehicles can produce much less pollution
than individual vehicles per passenger mile. In fact, public transportation use
in the United States reduces our nation’s carbon emissions by 37 million metric
tons annually. This is equivalent to Washington, DC; New York City;
Atlanta; Denver; and Los Angeles combined stopping
using electricity.
See: Health: Carbon Monoxide
