Definition of Air pollution
Air pollution occurs
when the substances are in excessive level that could be harm to the human
health, animal and affect plant growth. These substances are known as ‘air
pollutants’.
Air pollution means
that any substances emitted into the air from an anthropogenic, biogenic or
geogenic sources which are adversely affects to human, plant, animal and causes
damage to property. “Air pollution is the excessive concentration of foreign
matter in the air which adversely affects the wellbeing of the individual or
causes damage to property” – American Medical Association.
Sources and classification of air
pollutants
Pollutant can be
classified as primary and secondary air pollutants. Primary air pollutants
those emitted directly into the atmosphere. The main primary air pollutants are
Carbon compounds, such
as CO, CO2, CH4 and VOCs
Nitrogen compounds,
such as NO, N2O, and NH3
Sulfur compounds, such
as H2S and SO2
Halogen compounds, such
as chlorides, fluorides and bromides
Secondary air
pollutants means those are not emitted directly into the atmosphere from
sources. The main secondary pollutants are;
NO2 and HNO3 formed
from NO
Ozone (O3) formed from
photochemical reactions of nitrogen oxides and VOCs
Sulfuric acid droplets
formed from SO2, and nitric acid droplets formed from NO2
Sulfates and nitrates
aerosols formed from reactions of sulfuric acid droplets and nitric acid
droplets with NH3
Organic aerosols formed
from VOCs in gas-to-particle reactions
Effects of Air pollution
Impact on Human Health
The air we inhale has a
quantitative and qualitative balance that maintains wellbeing of human health.
When this balance is disturbed or if it purity get polluted it may cause
adverse impact on human health. All impurities do not harm. It depends on
various factors / pollutants and their concentrations in the air.
Nature of the
pollutants
Concentration of the
pollutants
Duration of exposure
State of health of the
receptor / Individual susceptibility
Air pollution can cause
by both naturally and from man-made sources. Man-made sources include
industries, automobile and power generation. Major indoor air pollution sources
are tobacco smoke and combustion of solid fuels for cooking and heating.
Health effects occur
due to the contact between the body and the pollutants. Exposure of air
pollution can cause acute (short term) and chronic (long term) health effects
on human. Acute effects are immediate and reversible. It includes common health
effects. Such as eye irritation, headaches. Chronic effects are take time to
visible and not reversible. It cause decreased lung capacity and lung cancer
which result from long-term exposure of toxic air pollutants.
Air pollution can also
indirectly affect human health through acid rains. It enters to the human body
through polluted water and food chain. Acid precursors are airborne pollutants
and they form acids through oxidation and chemical interaction with water vapor
in the atmosphere.
Approaches to measuring
health impacts of air pollution
Three methods are available
for measure the impacts of air pollution on people. They are;
Individual exposure
levels
Clinical studies
Epidemiology
Individual exposure
levels to air pollutants dependent on concentrations and dosages of air
pollutants, state of health and duration of exposure of the body. Effects observation
includes respiratory diseases, irritation of eyes, and reduction in physical
activity and many other physiological responses. Generally the effects of air
pollutants related with the state of health and age group of the individual.
For example exposure of pollution becomes risk for those who have chronic
diseases of the lungs or heart.
Clinical studies
involve who are exposed to air pollution under uncontrolled conditions. The
studies of truck drivers, traffic policemen and factory workers can give
valuable information about the vulnerable occupational group of people. It also
includes the observation of polluted areas data. Epidemiology mainly involve
the study of the distribution of specific diseases and the determine factors.
Impacts on plants
Air pollution has
adverse impact on plants and animals. Sulphur dioxide, various pesticides and
new industrial processes are the main sources for the pollutant that cause
complete destruction of vegetation.
These pollutants
interfere with plant growth and the phenomenon of photosynthesis. Exposure to
air pollution in plants cause acute injury and chronic injury. The damage reach
the plant through leafs. It takes several forms.
Necrosis – Killing or
collapse of tissue
Chlorosis – loss or
reduction of the green plant pigment, chlorophyll
Abscission – Dropping
of leaves
Epinasty – Downward
curvature of the leaf due to higher rate of plant growth
Effects of air pollution on
animals
Farm animals exposed to
pollution in two ways. (i) Accumulation
of air-borne contaminant in the vegetation and forage. (ii) They get poisoning
when they eat contaminated vegetation. Fluorine, arsenic and lead are the three
main pollutants cause damage to livestock.
Cattle and sheep are
the most vulnerable animals to fluorine toxicities. Fluorine poisoning cause
lack of appetite, rapid lose in weight, decline in health and vigour, lameness,
periodic diarrhea, muscular weakness and death, general ill health due to
malnutrition, lowered fertility, reduced milk production and growth
retardation.
Arsenic occurs due to
various industrial process and smelters. Arsenic in dusts or sprays on plants can
lead to poisoning of cattle; symptoms of arsenic include severe salivation,
thirst, vomiting, feeble and irregular pulse and respiration. It affects animal
central nervous system and cause dull, lack of appetite and weight loss in
animals.
Smelters, coke ovens
and other coal combustion process are the main sources for air-borne lead. Lead
poisoning causes prostration, staggering and inability to raise symptoms.
Animals pulse gets weak and some may fall suddenly stiffens in legs, and have
convulsions. Other symptoms in cattle are grinding of the teeth and rapid
chewing of the cud.
Pollution is now
beginning to affect domestic animals also. Many dogs suffer from coughs, nose
and throat diseases due to increasing air pollution.
Air quality Management
Poor air quality
adversely affects the productivity of people and national economic growth.
Therefore take action to minimize the air pollution. Air quality management includes
various aspects of pollution control measures. Industrial expansion is the
major contributor of air pollution. Another significant pollution sources are
vehicular traffic and thermal power generation.
In transport sectors
air pollution increase due to poor maintains of vehicles and they accelerated
air borne particles in atmosphere. High traffic congestion of vehicles usage increases
the emissions of carbon monoxide and volatile organic compounds. Therefore
proper air quality monitoring system and transport management system are
require for maintain the air quality.
Reduce gasoline
consumption: Reduce daily usage of vehicle transport. Use public transport and
take walk, bike are the practical solutions to mitigate the air emissions.
Replace the outdated fleet of buses, old engines rains and introduce electric
trains to reduce the CO2 emission through fuel saving. Establish an
enforcement of vehicles emission standards, fuel emission standards and
emission standards and implement a vehicle emission testing programs to mitigate
air pollution.
Emission from
industrial sources can control through adopt a modified technologies. Many of
the industries use outdated technology and cannot adopt new technology or
pollution control equipment due to lack of physical space for installation
which was established prior to 1980. But many governments started industrial
process with environmentally – friendly technologies. Reduction of CO2 emission
can be achieved through fuel switching by improving combustion.
Air pollution
mitigation requires both global and local coordination. The European Union
established an Emission Trading Scheme (EU ETS) to reduce emissions from power
plants and large industries. In addition European commission introduced an
Energy Efficiency Action plan in October 2006 to reduce the energy consumption
by 20% in 2020. Developing countries are making effort to reduce their
emissions by adopting domestic and international policies to increase
efficiency, expand renewable energy and promote sustainable development.
The Kyoto protocol
treaty which was adopted by the United Nations Framework Convention on Climate
Change (UNFCCC) established to limit the greenhouse gases. The Kyoto protocol
introduced three flexibility mechanisms for developed countries to achieve
their emission reduction targets. They are Clean Development mechanism (CDM),
Joint implementation (JI) and Emission Trading (ET). Under this treaty Carbon
Trading international market introduced as a global strategy to traded
reductions of greenhouse gases at international market at competitive prices.
The clean Development
Mechanism (CDM) is the only mechanism that both developed and developing
countries can participate. Implementing projects in developing countries that
reduces the GHG emissions and selling the amount avoided to developed countries
is called CDM or Carbon trading.
Carbon trading can be
undertaken by implementing two types of projects: Emission avoidance projects
and Green House Gas Removal or Sink projects. Clean Development mechanism (CDM)
or sink projects include forestry for carbon trading. Forests provide a
mechanism of carbon sequestration. Afforestation and reforestation projects are
eligible for forestry CDM according to Bonn agreement.
References:
1. Global Warming &
Environmental Threats; Economic review (June/July 2008); A peoples Bank
Publication.
2. Barbara
Murck (2005); Environmental Science ; John Wiley & Sons, Inc; USA
3. Kevin
T. Pickering an Lewis A.Owen (1997); An introduction to global environmental
issues; London and New york
