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Review of Air Quality Monitoring: Case Study of India

Air pollution is one of the foremost and grave public health and environmental anxiety in most of evolving countries. Objectives: The objective of this paper is to provide insight details about current situation of air quality across various cities present in India, along with countless origins and effects of air pollution. An attempt is made to make people aware about various types of gases and particulate matter present in air highlighting their effects on environment along with the various ways of overcoming this situation. Methods: The National Air Quality Index (NAQI) ensures comparison amongst various cities so that new measures can be formulated in order to decrease the quantity of particulate matter present in air. In this paper concentration of various pollutants along with various harmful gases for various cities of India are analyzed based on past NAQI data thereby highlighting those areas which are under extensive menace of pollution. Findings: It has been perceived from past few years that the rate at which Urban Air Pollution across India has grown is alarming due to severe unsafe web of particulate matter (PM) and harmful gases present in air that living organism’s breath. Levels of particulate matter are extremely higher in all cities of India. Only few cities are such that can be emphasized where Air Quality Monitoring (AQM) has started due to which they show some enhancement in quality of air but mostly affected areas are small and medium sized towns which suffer from phenomenal spurt in pollution in very critical manner. Due to increase in immense number of vehicles, industries and manufacturing units has resulted in excess assembly of pollutants in air making air pollution as a state of national emergency across various cities around the country.


Introduction
For developing countries like India air pollution has tremendous impact on human vigor, agricultural practices, climatic variations and overall changes in ecosystem. Every year almost six lakh Indians die due to side effects of air pollution which has become fifth leading cause of death across the country after other causes like water pollution, nuclear pollution etc. Out of these, almost 35,000 death occur in national capital i.e. Delhi, rest 15,000 deaths are recorded in each industrial areas 1 . Though almost complete key attention is paid towards national capital due to which other cities and towns are suffering. Other cities that are suffering due to extensive threat of pollution are Ghaziabad, Punjab, Patna, Raipur, Agra and many more. Almost all the cities are suffering due to increase in concentration of Particulate Matter (PM) in air along with gaseous pollutants like oxides of nitrogen, sulphur along with other toxic materials that are already causing serious damage to environment. Only few cities are such that can be highlighted where Air Quality Monitoring (AQM) has started due to which they show some improvement in quality of air but mostly affected areas are small and medium sized towns which suffer from phenomenal spurt in pollution in very critical manner.
Keywords: Air Quality Monitoring, Gaseouspollutants, National Air Quality Index, Particulate Matter The central pollution control board that has started a national air quality monitoring program since 1984 under which various air pollutants like sulphur dioxide (S0 2 ), nitrogen dioxide (NO 2 ) and particulate matter having size less than 10 micron (PM10), covering 254 towns and cities in 29 states and five union territories. This program operates 612 monitoring stations present at different places in various cities. From continuous monitoring it has been observed that 46 cities in India having population greater than one million are excessively polluted.
The aim of this paper is to provide comprehensive review of air quality monitoring practices in India with objectives: to identify critical problem areas suffering from severe air pollution by an objective assessment of state of practice and to recommend suitable measures for improvement were ever applicable. In this paper ten major cities have been taken into consideration for air quality monitoring, these cities have been so chosen bearing in mind the fact that these cities are major center for commercial, industrial and tourist activities due to which rate of environment worsening is high.

Air Pollutants
Major pollutants present in air are basically categorized into following types: • Carbon Compounds: Oxides of carbon (Carbon dioxide (CO 2 ), carbon monoxide (CO)) mostly released from all vehicles and burning of fossil fuels.

Sources
There are numerous sources for occurrence of air pollution; some of these sources can be widely classified into following types.

Vehicles -A Major Cause
The toxic pollutants released from various vehicles are major source of air pollution. Due to rapid growth in use of personal vehicles rather than using private vehicles have not only increased extensive demand of vehicle oil but also have increased the concentration of particulate matter in air 2 . This steady shift has also led to change of transport pattern as nowadays people prefer roadways rather than using railways. By the end of 2010 it was estimated that India has more than 5 million vehicles running out of which 65% vehicles are two wheelers working on petrol. Across major cities of country 800 to 1000 tons of pollutants are released into air daily out of which 50 percent come from vehicle exhausts. It has been estimated that by the end of 2035 the total Indian fuel demand will be six times the fuel demand recorded in year 2005. There is a wider shift in choice of persons personal vehicles as most of the people prefer bigger vehicles that are usually compact, medium in size and use high quantity of fuel. It has been estimated by the end of 2030-31 that if 50 percent of India's fuel efficiency is achieved by revising energy policies then India can save 65 percent of its total energy consumption and decrease CO 2 emissions equal to removing seven millions of four wheelers.
Overall 15 percent of total CO 2 is released into air through transport sector in India . It has been found that 6 percent increase in quantity of CO 2 emissions occurs per year 3 . Table 1, gives the average data related to various pollutants released from vehicles for metropolitan cities

Industrial Wastes and Thermal Power Stations
Due to rapid industrialization and establishment of multiple factories, large number of industries have been running from past releasing chief pollutant gases SO 2 and NO 2 . It has been observed that Mathura based oil refineries are leading to deterioration of Taj Mahal and other monuments at Fatehpur Sikri 2 . Along with industries there are numerous thermal power plants where coal consumption is in millions of tonnes and chief pollutants released are fly ash, hydrocarbons, S0 2 along with other gases 4 . Table 2 gives the data related to various pollutants released from a 200 MW thermal power plant where, total coal consumed is 1400 tonnes per day.

Other Anthropological Sources
Apart from major sources given above, the following activities also play a vital role in causing air pollution: • Burning up of crop wastes by farmers.
• Refrigeration activities and sprays of aerosol.
• Methane generation due to waste deposition in landfills.
• Verification of nuclear weapons by army personnel's.
• Dust particles generated from any natural sources.
• Uncertain volcanic activities producing high content of fumes, ash and other severe gases. • Uncertain Forest fires.
• Decomposition of animals leading to production of methane.

Effects of Air Pollution
Air pollution causes wide range on side effects not only on environment but also on the various organisms dwelling in that environment. Some of those side effects have been summed up below 5 • Enhanced ageing of lungs along with damage of lung capacity along with short term irritation in sense organs. • Main cause of asthma, bronchitis, emphysema etc.
• Reduction in life span.
• Damage of shoots and upper vegetative cover of plants due to acid rain 6 . • Depletion of soil nutrients due to reaction of nutrients with acid rain. • Changes in physical appearance in vegetative cover due to intake of sulphur dioxide and ozone (flecking, tanning or bleaching) • Eutrophication in rivers and other water bodies.
• Damage to constructed structures due to acid rain.

Research Facts about Air Pollution in India
• It has been observed that most of the established industries and factories do not obey environmental safety guidelines and laws 7 . • From recent 2015 survey, India is labelled to be world's seventh environmentally unsafe country. • Three parts of total pollution is caused due to automobiles running on daily basis emitting about 40 different types of pollutants 7 . • Selling of adulterated fuels in India is so common in practice that in return environmental air quality is paying the price of using it?. • Bangalore city is termed as asthma city as about 30% children at that place suffer from asthma caused due to air pollution. • Rate of cancer patients is also increasing in India, as per National Cancer Control Program (NCCP) by the year 2026 about 1.4 million people will be suffering from cancer.
• If considered hospitalized persons, 13% deaths occur due to acute respiratory disorders.

Current Status of Air Quality Monitoring in India
The National Air Quality Index (NAQI) has been announced as a regulatory body by government as a reporting standard to measure air quality levels to ensure comparison between various cities so that new measures can be devised in order to decrease the quantity of pollutants present in air 8 . No doubt the NAQI inadequately reveals that 23% of workstations across India are on alarming rate showing more than 70% of increase above permissible limits thus making air pollution as a state of national emergency across various cities around the country 9 . Comparison was done of Indian pollution levels with china due to the fact that population level of China is greater than India. On comparing the pollution levels between Indian cities and cities of China, it has been found that Indian pollution level is increased to a greater extent as compared to China clearly giving us an idea that these levels are ten times greater higher than WHO standards highlighting air pollution as a major concern in India. As per the analysis performed by Green Peace India, Figure 1 on data provided on NAQI interface it was observed that air pollution is not only a major concern in National Capital only but people need to focus on other areas also apart from capital of country as the rate of pollution is alarming across various regions of India. While the basic motive of the organization is to reduce the levels of particulate matter PM10 and PM2.5 .As per World Health Organization, Figure 2 it was found that National Capital has pollution level 12 times higher than permissible limits along with other cities -Lucknow, Faridabad, Kanpur, Agra and Varanasi whose levels have exceeded ten times. As per World Health Organization latest report of 2014, 20 cities were shortlisted as world's most air polluted cities out of which 13 were from India. No doubt the basic reason for such a situation is rapid industrialization and uncontrolled motorization thus attention is to be given towards such situation as it has become a global issue now 10 .

Agra
It is spread over an area of approximately 140 sq. km with population of 9.5 lakhs along with moving population of 20,000 as per 1991 census. Main causes of air pollution are foundry industries which practices coal as a fuel along with vehicular discharges as vehicular growth is high. As per National Ambient Air Quality Standards (NAAQS) level of SO 2 was found to be lower in all monitored periods but NO 2 , RSPM and SPM levels were found to be cooperatively exceeding .The concentration of pollutants were found to be higher in winter seasons but were lower in summer and monsoon seasons. As per 2005 NAAQS survey, concentration of pollutants found is given in Table 3.

Ahmadabad
It is also known as Manchester of East due to presence of large number of textile industries. Being one of industrial cities of India, main sources of pollution being industrial and vehicular sources along with coal fired hearth in slum units and bakery units. As per National Ambient Air Quality Standards (NAAQS) level of SO 2 and NO 2 was found to be lower in all monitored periods but RSPM and SPM levels were found to be cooperatively exceeding. The concentration of pollutants were found to be higher in winter seasons but were lower in summer and monsoon seasons as per 2005 NAAQS survey, concentration of pollutants found is given in Table 4.

Bangalore
It is considered to be biggest industrial, commercial, educational, information technology and bio technology center in India, along with major sources diesel generator sets are continuous source of pollution. As per National Ambient Air Quality Standards (NAAQS) level of SO2 was found to be very low and NO2 was found to be moderate in all monitored periods but RSPM and SPM levels were found to be cooperatively exceeding. The concentration of pollutants were found to be higher in winter seasons and summer but were lower in monsoon seasons as per 2005 NAAQS survey, concentration of pollutants found is given in Table 5.

Chennai
It is considered to be fourth largest city in India with surface, sea and air transport services with other sources of pollution being industrial boilers and generator sets .As per National Ambient Air Quality Standards (NAAQS) level of SO 2 and NO 2 was found to be lower in all monitored periods but RSPM and SPM levels were found to be cooperatively exceeding. The concentration of pollutants were found to be higher in winter seasons but were lower in summer and monsoon seasons. As per 2005 NAAQS survey, concentration of pollutants found is given in Table 6.

Delhi
It is the capital of India considered to be most polluted in India with lot of vehicular emissions and thermal power plants releasing SPM, hydrocarbons, CO, sulphur, oxides of nitrogen and carbon monoxide 11 . Air pollution load (tonnes/ day) from thermal plants is given in Table 7. As per National Ambient Air Quality Standards (NAAQS) level of SO2 and NO2 was found to be lower in all monitored periods but RSPM and SPM levels were found to be cooperatively exceeding. in addition to these other pollutants found in the area was carbon monoxide (CO) whose level was very high in initial years but it has lowered to some extent due to follow up of pollution control measures in city .The concentration of pollutants were found to be higher in winter seasons but were moderate in summer and lower in monsoon seasons As per 2005 NAAQS survey, concentration of pollutants found is given in Table 8.

Hyderabad
It is known for wealthy Nizam's and reported to have 11 lakh vehicles around city. With vehicles as foremost cause of pollution subsidizing to bulk of unburnt hydrocarbon and carbon monoxide. Levels of SO 2 and NO 2 found to be lower but RSPM and SPM are found to be very high. The concentration of pollutants were found to be higher in winter seasons but were moderate in summer and very lower in monsoon seasons .As per 2005 NAAQS survey, concentration of pollutants found is given in Table 9.

Jharia
It is widely famous hub for coal mining activities with numerous mines operational from last 40 decades.
Additions to it are about 103 small scale industries present in the town. As per National Ambient Air Quality Standards (NAAQS) level of SO 2 was found to be lower in all monitored periods along with moderate levels of NO 2 but RSPM and SPM levels were found to be cooperatively exceeding. The concentrations of pollutants were found to be higher in winter seasons but were moderate in summer and lower in monsoon seasons. As per 2005 NAAQS survey, concentration of pollutants found is given in Table 10.

Kanpur
It is considered to be main center of industrial and commercial activities and biggest producer of textiles and leather products. Levels of SO 2 and NO 2 found to be lower but RSPM and SPM are found to be very high. The concentration of pollutants were found to be higher in winter seasons but were moderate in summer and lower in monsoon seasons As per 2005 NAAQS survey, concentration of pollutants found is given in Table 11.

Kolkata
It is known for iron foundries, mills, metal furnishing units etc. apart from vehicles pollutants are generated from various large scale industries, power plants, domestic units. As per National Ambient Air Quality Standards (NAAQS) level of SO 2 was found to be lower in all monitored periods along with high levels of NO 2 but RSPM and SPM levels were found to be cooperatively high .
As per 2005 NAAQS survey, concentration of pollutants found is given in Table 12.

Lucknow
It is known as most populous state having silver, copper, brass and cotton small and medium industries. As per National Ambient Air Quality Standards (NAAQS) level of SO 2 and NO 2 was found to be lower but RSPM and SPM levels were found to be cooperatively high. As per 2005 NAAQS survey, concentration of pollutants found is given in Table 13.

Results and Discussion
On comparing concentration of levels of pollutants for various cities, as per Figure 3, 4, 5, 6 it was found that: • SO 2 concentration of Hyderabad was found to be lowest and highest was of Chennai. • NO 2 concentration of Kanpur was found to be lowest and highest was of Delhi and Bangalore. • RSPM concentration was found critical in all cities among which low critical level was found in Hyderabad and extreme critical levels were found in Lucknow, Kanpur and Agra. • SPM concentration was found very critical in all in all cities among which low critical level was found in Chennai and Bangalore and extreme critical levels were found in Lucknow, Kanpur and Agra. • Mostly concentration of pollutants was found to be higher in winter seasons.

Preventive Measures Followed in India
Air pollution and control act passed in 1981 and amended in 1987 to ensure prevention, control and abatement of air pollution in India. Supreme Court has taken air pollution prevention seriously by taking several initiatives like making use of compresses natural gas in public services mandatory due to which cumulative percentage of pollution has decreased. Reduction of pollution causing substances in fuels like extraction of excess sulphur and benzene from diesel, use of standardized fuels along with increased rate of use of LPGs replacing biomass fuels have also helped in decline of pollutants present in air in most parts of India [12][13] . Introduction of metro's have also helped in decrease in pollution rates as use of personal vehicles have decreased to larger extent 7 . In past shut down of hazardous gas emitting industries, hot mix plants and brick producing kilns being operated in Delhi have also made people to think about nature, extent and types of pollutants released in air, along with it introduction of unleaded petrol from year 1998 in vehicles have also helped in reduction of air pollutants. In most of cities in India a provision for vehicles is made in which vehicles is certified as "pollution under control" with validity of three months after proper testing under norms of Bharat Stage 2 nd or higher emission norms, along with it pollution control board present in every state perform ambient air quality monitoring at workstations present all over states across the country to keep continuous tract about air pollution levels and applying corrective actions wherever necessary 14 . Many organizations have been established that work in hand with government to make necessary efforts to reduce air pollution for example Energy and resource institute, and Indian association for air pollution control, society of Indian automobile manufacturers etc are actively involved in prevention of air pollution.

Conclusion
From the given data it can be concluded that level of RSPM and SPM are extremely higher in all cities of India.
• Major cause of generation of pollutants was common in all monitored cities i.e. vehicles and automobiles. • In past, several initiatives have been taken by Indian government to reduce air pollution across country but still lot of efforts need to be done to reduce it further . • It is better to prevent air pollution rather than allowing it to increase and well know proverb 'charity begins at home' suits here, we need to understand the causes, effects and measures to reduce pollution then only we can decrease pollution levels to ensure better environment for future generations . • More efforts are required for making air quality monitoring a national issue by creating more awareness and following certain laws and rules to decrease the level of pollutants in air. • One needs to use public automobiles often and try to avoid use of excess personal automobiles as it will help to not only to decrease the excess vehicle congestion on roads but also help in decreasing pollution. • Energy efficient commodities must be utilized wherever possible as they tend to save energy along with having low negative effects. • Existing policies and strategies need to be strengthened more to ensure more positive results. • People should prefer public transport rather than using personal vehicles. • More vehicle evaluation on regular intervals needs to be done based on air pollutants emissions and proper certification should be given to vehicles. • Awareness needs to be created among people related to health effects of air pollution so that people start taking it seriously and breathe a safer and pure air.

Acknowledgement
For all the work done in this review paper I would like to express my deepest gratitude to my mentor, Miss. Kirti Goyal Assistant Professor, Environment Department, Lovely Professional University whose contribution in stimulating suggestions, guidance and encouragement from initial to final level in collecting and analyzing various data helped me alot in writing this review paper.