AIR POLLUTION

Why in News?

Aspects of pollution remain a great concern as Data on industry emissions for Rajasthan and Chhattisgarh was not complete or easily accessible in the public domain, the Central Pollution Control Board (CPCB). 

1. Background

• The origin of air pollution on the earth can be traced to the times when man started using firewood as a means of cooking and heating. 
• Hippocrates mentioned air pollution in 400 BC. With the discovery and increasing use of coal, air pollution became more pronounced especially in urban areas. 
• It was recognized as a problem 700 years ago in London in the form of smoke pollution, which prompted King Edward I to make the first anti-pollution law to restrict people from using coal for domestic heating in the year 1273. 
• In the year 1300, another Act banning the use of coal was passed. 
• Defying the law led to the imposition of capital punishment. 
• Despite this air pollution became a serious problem in London during the industrial revolution due to the use of coal in industries. 
• The earliest recorded major disaster was the ‘London Smog’ that occurred in 1952 that resulted in more than 4000 deaths due to the accumulation of air pollutants over the city for five days. 

• The Air Pollution Control Act in India was passed in 1981 and the Motor Vehicle Act for controlling air pollution, very recently. 

• These laws are intended to prevent air from being polluted. 
• The greatest industrial disaster leading to serious air pollution took place in Bhopal where extremely poisonous methyl isocyanide gas was accidentally released from the Union Carbide’s pesticide manufacturing plant on the night of December 3rd 1984. 
• The effects of this disaster on human health and the soil are felt even today. 

2. About Air pollution

• Air pollution occurs due to the presence of undesirable solid or gaseous particles in the air in quantities that are harmful to human health and the environment. 
• Air may get polluted by natural causes such as volcanoes, which release ash, dust, sulfur and other gasses, or by forest fires that are occasionally naturally caused by lightning. 
• However, unlike pollutants from human activity, naturally occurring pollutants tend to remain in the atmosphere for a short time and do not lead to permanent atmospheric change.
• Pollutants that are produced in the atmosphere when certain chemical reactions take place among the primary pollutants are called secondary pollutants. Eg: sulfuric acid, nitric acid, carbonic acid, etc.

3. Major Pollutants and their Respective properties 

3.1. Carbon Monoxide 

• Carbon monoxide is a colourless, odourless and toxic gas produced when organic materials such as natural gas, coal or wood are incompletely burnt. 
• Vehicular exhausts are the single largest source of carbon monoxide. 
• The number of vehicles has been increasing over the years all over the world. Vehicles are also poorly maintained and several have inadequate pollution control equipment resulting in the release of greater amounts of carbon monoxide. Carbon monoxide is however not a persistent pollutant. 
• Natural processes can convert carbon monoxide to other compounds that are not harmful. 
• Therefore the air can be cleared of its carbon monoxide if no new carbon monoxide is introduced into the atmosphere 

3.2 Sulfur oxides 

• Sulfur oxides are produced when sulfur-containing fossil fuels are burnt. 

3.3 Nitrogen Oxides 

• Nitrogen oxides are found in vehicular exhausts. Nitrogen oxides are significant, as they are involved in the production of secondary air pollutants such as ozone. 3.4 Hydrocarbons 
• Hydrocarbons are a group of compounds consisting of carbon and hydrogen atoms. 
• They either evaporate from fuel supplies or are remnants of fuel that did not burn completely. 
• Hydrocarbons are washed out of the air when it rains and runs into surface water.

3.4 Hydrocarbons 

• Hydrocarbons are a group of compounds consisting of carbon and hydrogen atoms. 
• They either evaporate from fuel supplies or are remnants of fuel that did not burn completely. 
• Hydrocarbons are washed out of the air when it rains and runs into surface water. They cause an oily film on the surface and do not as such cause a serious issue until they react to form secondary pollutants. 
• Using higher oxygen concentrations in the fuel-air mixture and using valves to prevent the escape of gasses, fitting catalytic converters in automobiles, are some of the modifications that can reduce the release of hydrocarbons into the atmosphere. 

3.5 Particulates 

• Particulates are small pieces of solid material (for example, smoke particles from fires, bits of asbestos, dust particles and ash from industries) dispersed into the atmosphere. 
• The effects of particulates range from soot to the carcinogenic (cancer-causing) effects of asbestos, dust particles and ash from industrial plants that are dispersed into the atmosphere.
• Repeated exposure to particulates can cause them to accumulate in the lungs and interfere with the ability of the lungs to exchange gasses. 

3.6 Lead 

• Lead is a major air pollutant that remains largely unmonitored and is emitted by vehicles. 

• High lead levels have been reported in the ambient air in metropolitan cities. Leaded petrol is the primary source of airborne lead emissions in Indian cities. 

4. Air Pollution in India 

• The World Health Organization (WHO) which rates only megacities of the world have rated Delhi the fourth most polluted city in the world. 
• However compared to other cities in India, Delhi is not at the top of the list of polluted cities. 
• Our country has several pollution hotspots. 
• Nitrogen dioxide levels in most major cities are generally close to the acceptable annual standard of 60 mg/m3. 
• However sharp increases have been noticed in a few cities with heavy vehicular traffic and density as in a few locations in Kolkata and Delhi indicating a stronger impact of traffic. 
• The CPCB indicates vehicles as one of the predominant sources of air pollution. 

5. Way Forward and Need of the Hour 

• Putting a greater emphasis on pollution prevention rather than control 
• Reducing the use of fossil fuels 
• Improving the quality of vehicular fuel 
• Increasing the use of renewable energy