Air pollutants may occur in gaseous or particulate form and may be organic or inorganic. Based on the origin of pollutants, here we will show classification of air pollutants they can be as primary or secondary pollutants.
Classification of Air Pollutants
1. Primary Pollutants
These are emitted directly from the point source, e.g., carbon monoxide (CO), oxides of nitrogen (NO), oxides of Sulphur (SO), hydrocarbons, radioactive substances, etc. It is the first classification of air pollutants.
2. Secondary Pollutants
These are formed by the interaction of primary pollutant(s) with other primary pollutants or with some natural constituents of the atmosphere, e.g., ozone (O3), peroxyacetyl nitrate (PAN), photochemical smog, etc. It is the secondary classification of air pollutants.
Whitepaper: Indoor Air Pollution
The most important indoor air pollutant is radon gas. Radon gas and its radioactive daughters are responsible for yearly lung cancer deaths. Radon can be emitted from building materials like bricks, concrete, tiles, etc., which are derived from soil containing radium. Radon is also present in groundwater and natural gas and is emitted indoors while using them.
Many houses in under-developed and developing countries, including India, use fuels like coal, dung cakes, wood, and kerosene in their kitchens. Indoor air pollutants are also the classification of air pollutants. The complete combustion of a fuel produces carbon dioxide, which may not be toxic. However, incomplete combustion produces the toxic gas carbon monoxide. Coal contains varying amounts of Sulphur which, on burning, produces Sulphur dioxide.
Fossil fuel burning produces black soot. These pollutants, i.e., CO, SO, soot, and many others like formaldehyde, and benzo- (a) pyrene (BAP), are toxic and harmful to health. BAP is also found in cigarette smoke and is considered to cause cancer. A housewife using wood as fuel for cooking inhales BAP equivalent to 20 packets of cigarettes a day.
Whitepaper: Outdoor Air Pollution
The sources of outdoor air pollution are:
1. Burning of fossil fuels.
(i) in automobiles, domestic cooking, and heating.
(ii) in power stations and industries (primarily the chemical, metal, and paper industries).
2. Mining activities leading to dust as well as fires.
3. Burning nuclear fuels, biofuels, tropical rainforests, and wastes of all kinds.
4. Natural emissions from animals and decaying organic matter. It is one of the classification of air pollutants.
Heavy Effects of Outdoor Air Pollution
At low levels, air pollutants irritate the eyes and cause respiratory tract inflammation. It can also accentuate skin allergies. If the person already suffers from a respiratory illness, air pollution may lead to the condition becoming chronic later.
Many pollutants also depress the immune system, making the body more prone the infections. Carbon monoxide from automobile emissions can cause headaches at lower levels and mental impairment, and even death at higher levels of air pollution.
Particular matter can reduce visibility, soil clothes, corrode metals, and erode buildings. On a larger scale, air pollution leads to acid rain, ozone layer depletion, and global warming.
Most Effective Ways to Control Outdoor Air Pollution
Outdoor air pollution can be reduced by adopting cleaner technologies, reducing pollution at source, implementing laws and regulations to make people pollute less, and introducing Automobiles emissions can be reduced through various measures:
- Making cleaner and fuel-efficient cars.
- Using lead-free petrol in existing cars.
- Introducing policies that encourage the building and use of mass transit systems and discourage the use of personal transport. For example, efficient and low-cost public transport, congestion charges in city centers, separate lanes for carpools, a heavy tax on personal cars, tax incentives on electric cars, etc. It shows the levels of air pollution in country.
- Shifting from diesel to natural gas (CNG) as a fuel for trucks and buses.
Different Levels of Air Pollution in India
The air is severely polluted in many Indian cities, with excessive concentrations of suspended particulate matter (SPM), nitrogen oxide, and sulfur dioxide. The World Health Organization (WHO) has consistently ranked Delhi as the fourth most polluted city in the world. The main cause for this increasing levels of air pollution was vehicular emissions, followed closely by industrial pollution. The number of motor vehicles in India increased from 300,000 in 1951 to 37.2 million in 1997. Of these, over 30 percent are in the 23 metropolitan cities. Delhi alone accounts for 8 percent of the total.
The exponential growth of vehicles, outdated vehicle technology, bad fuel quality, poor maintenance of vehicles, poor traffic management, and planning all contribute to vehicular pollution. The problem is compounded by the unwillingness of vehicle owners and the auto industry to accept emissions norms and the lack of efficient public transport.
The older vehicles still use leaded petrol although unleaded petrol is now increasingly available. It will increase the levels of air pollution. Trucks and buses run on diesel, which has a high Sulphur content. The old engines emit vast quantities of SPM, leading to heavy air pollution in many cities. Polluted air is affecting people’s health, particularly that of children. Between 1991 and 1995, the annual number of premature deaths traced to air pollution increased from 40,000 to 52,000. In Delhi, one out of every 10 school child has asthma.
Traditional stoves that use wood or coal spew out poisons that women In rural areas, indoor pollution is taking a toll on women’s health. Inhale directly. This is equivalent to smoking 100 cigarettes a day! Many deaths occur in North India during the winters when doors and windows are closed, and poisonous smoke from the stove collects indoors. There have been campaigns to substitute these inefficient and polluting stoves with smokeless chulhas. The effort has, however, failed to make a good dent in this huge problem.
Regulations on Automobile Emissions in India. The Indian government began regulating automobile emissions in 1991. Since then, it has been gradually making these limits more stringent. In the year 2000, the government introduced the Bharat Emission Norms modelled on the basic Euro Norms of the European Union.
Bharat-III norms for passenger cars will come into effect from April 2005 in 11 metros-Bangalore, Delhi, Mumbai, Kolkata, Chennai, Hyderabad, Ahmedabad, Pune, Surat, Kanpur, and Agra to reduce the levels of air pollution. This will account for 40 percent of the total cars sold in India. The rest of the country will shift to Bharat-II norms.
In the 11 designated cities, the new Bharat-III petrol cars would have 28 percent lower emissions than current Bharat-II cars and 89 percent lower emissions than cars manufactured in 1991. Similarly, there would be an almost 30 percent reduction in emissions among Bharat-III diesel cars compared to the Bharat-II cars. Compared to 1992 diesel cars, the reduction in emissions would be 72 percent.
Lead has been phased out of automobile fuel with effect from February 2000. New stringent norms for petrol and diesel will come into effect from 2005. The Supreme Court of India has taken a special interest in keeping the air clean, particularly in Delhi. Thanks to the court’s orders, implemented by the Delhi government, the air quality in Delhi has improved.