New Delhi, Gwalior, Varanasi and Kanpur were among the 14 Indian cities that figured in a list of 20 most polluted cities in the world, based on their toxic air quality, data released by World Health Organization showed. On PM 2.5, most polluted city is Varanasi, Prime Minister Narendra Modi's constituency. Major sources of air pollution from particulate matter - pollutants like sulphate, nitrate and black carbon - include inefficient use of energy by households, industry, agriculture and transport sectors, and coal-fired power plants. The study found that "around seven million people die every year from exposure to fine particles in polluted air".NEW DELHI: According to the World Health Organisation (WHO) global air pollution database released in Geneva, India has 14 out of the 15 most polluted cities in the world in terms of PM 2.5 concentrations -- the worst being Kanpur with a PM 2.5 concentration of 173 micrograms per cubic metre, followed by Faridabad, Varanasi and Gaya.Other Indian cities that registered very high levels of PM2.5 pollutants are Delhi, Patna, Agra, Muzaffarpur, Srinagar, Gurgaon, Jaipur, Patiala and Jodhpur, followed by Ali Subah Al-Salem in Kuwait and a few cities in China and Mongolia.India's financial capital Mumbai is the world's fourth most polluted megacity. The study considered PM2.5 (particulate matter of diameter less than 2.5 micrometres) and PM10. PM2.5 is more dangerous than PM10. The period considered for the study was 2010 to 2016.The report states that 9 in 10 people in the world breathe polluted air. In a statement, it said 7 million people die every year because of outdoor and household air pollution. "Ambient air pollution alone caused some 4.2 million deaths in 2016, while household air pollution from cooking with polluting fuels and technologies caused an estimated 3.8 million deaths in the same period,” it said. More than 90% of air pollution-related deaths occur in low- and middle-income countries, mainly in Asia and Africa, followed by low- and middle-income countries in theeastern Mediterranean region, Europe and the Americas. "Air pollution threatens us all, but the poorest and most marginalised people bear the brunt of the burden," WHO chief Tedros Adhanom Ghebreyesus said in a statement. WHO highlighted that air pollution is mainly responsible for non-communicable diseases (NCDs), causing an estimated one-quarter (24%) of all adult deaths from heart disease, 25% from stroke, 43% from chronic obstructive pulmonary disease and 29% from lung cancer. The organisation stressed that although its report provides air quality data from more than 4,300 cities and towns in 108 countries, there was an unevenness in the information received, with a dire lack of data from Africa and parts of the Western Pacific region. Only eight of the 47 countries in Africa provided air quality information about one or more of their cities. And while the database listed information on 181 Indian cities, it provided data for only nine Chinese cities. The WHO's collected annual mean concentrations of fine particulate matter (PM10 and PM2.5) includes pollutants, such as sulphate, nitrates and black carbon, which pose the greatest risks to human health. Major sources of air pollution from particulate matter include the inefficient use of energy by households, industry, the agriculture and transport sectors, and coal-fired power plants. In some regions, sand and desert dust, waste burning and deforestation are additional sources of air pollution . While Delhi is not the most polluted city in the world, it's hardly reason to cheer. Despite public outcry over severe air pollution, and both Centre and Delhi government taking up the issue, the report shows that Delhi's pollution levels improved only marginally between 2010 and 2014 but started deteriorating again in 2015. In 2016, the latest year in WHO's database, Delhi was in sixth spot, having recorded its highest pollution levels in six years. The city's PM 2.5 annual average was 143 micrograms per cubic metre, more than three times the national safe standard, while the PM 10 average was 292 micrograms per cubic metre, more than 4.5 times the national standard. The data source for Delhi is mainly from the Central Pollution Control Board (CPCB) (about 10 stations), although for the years 2015 and 2016 WHO also considered data from ministry of earth sciences (MoES) and US Environment Protection Agency's (EPA) Air Now. This may have also influenced the air pollution concentrations for 2015 and 2016, experts said. Ironically, as India's air pollution monitoring network improved in the past few years with more cities being monitored, the number of Indian cities in the top polluters' list zoomed."With improved air quality monitoring, we are beginning to understand the depth and spread of the air pollution problem in India. While Delhi is at the crossroads and is expected to bend the curve post 2016, other pollution hot spots are proliferating across the country," said Anumita Roy Chowdhury, executive director, Centre for Science and Environment (CSE)."This is a national public health crisis and the newly proposed national clean air action plan has to ensure stringent action in all cities to comply with clean air standards," Chowdhury said. In 2010, Delhi was the worst polluted city globally followed by Peshawar and Rawalpindi. Agra was the only other Indian city in the top 10 polluted (PM2.5) cities, in 2011 too Delhi and Agra were the only two Indian cities and Ulaanbaatar was the worst. But this started changing 2012 onward when 14 out of top 20 most polluted were in India. In 2013, 2014 and 2015 too, four to seven Indian cities were in top 20. But in the 2016 data released on Wednesday, 14 out of 15 most polluted are in India. The CPCB had recently claimed that Delhi's air pollution levels improved in 2017 as compared to 2016. The board, however, hasn't released the annual average PM 2.5 concentration for 2017 yet. A number of policies came into effect towards the end of 2016 - the graded response action plan (GRAP) in October, doubling of the environment compensation charge (ECC) on trucks in December 2015 and better coordination among NCR states on pollution control. The WHO report, however, doesn't reflect this because it considers annual PM 10 and PM 2.5 averages between 2010 and 2016. Experts are not sure what may have led to a sudden spike in Delhi's pollution levels in 2015 and 2016. "In 2015 and 2016, there were northwesterly winds in the crop burning season which brought particulate pollution from neighbouring states. These meteorological factors may have also accentuated air pollution in Delhi," said Dipankar Saha, former CPCB air lab head.In contrast, many Chinese cities are improving. In 2016 only four Chinese cities -Baoding, Hengshui, Xingtai and Anyang - were in top 20 compared to 14 Chinese cities, including Beijing, in 2013's top 20. Delhi and Beijing are often compared due to their high air pollution levels and policies like the odd-even road rationing measure or air pollution emergency action plan. However, WHO's recent data shows that Beijing's air pollution levels have been consistently reducing 2013 onwards.In 2016, Beijing's PM 2.5 concentration was 73 micrograms per cubic metre compared to Delhi's 143. "There are cities that have seen a decrease in PM2.5 level, Beijing and Mexico, if you look at the data. China has put a number of measures since 2013, from a National Action Plan of Air pollution Control, enforcement of environmental standards etc," WHO said, responding to Tol's In an alarming reflection of the city's air pollution levels, WHO ranked Mumbai as the fourth most polluted megacity in the world, up from last year's fifth place, also being ranked the 63rd most polluted city among 859 considered by the WHO around the world. Among 10 global megacities (habitation of above 14 million), Mumbai, with an average PM10 level of 1041g/ m3 (microgram per cubic metre), came after Delhi (which topped the list), Cairo and Dhaka. Shockingly, it was found to be more polluted than Beijing, which is always in news for its terrible smog-laden days, accompanied with pictures of people moving around in masks. Mumbai's air pollution is nearly as bad as Beijing's, but the city is not paying the required attention to this problem and that is alarming. It is time Mumbai woke up to the situation and took responsibility and react with the sort of urgency Bejing has reacted and how even Delhi is preparing to respond to its growing pollution," said Sunil Dahiya, senior campaigner, Greenpeace. Quite a few factors contribute to Mumbai's high air pollution levels. "Construction activity accounts for about 30% of dust particles, followed by vehicular emissions. In addition, open burning of garbage occurs in the city, adding to pollution," said Rakesh Kumar, director, National Environmental Engineering and Research Institute (NEERI). "Nevertheless, the Indian subcontinent cannot be directly compared with other regions of the world. Being in a tropical country, Indian cities have a lot of background pollutants like natural dust. This is why Indian cities have recorded higher level of pollutants (on the WHO list)." In Maharashtra, polluted cities include Pune, Navi Mumbai and Nagpur (not in that order). For Mumbai, WHO used data provided by the Maharashtra Pollution Control Board from its monitoring stations in Sion and Bandra and monitoring stations by System of Air Quality Weather Forecasting and Research (SAFAR). The Pink City too is not in the pink of health, according to the WHO report which said Jaipur is the most polluted city in the desert state, followed by Jodhpur, Kota, Alwar and Udaipur. The samples were collected in different years in different districts.Jaipur recorded the highest level of PM10 (Particles smaller than 10 microns) in the state. The international standards of air pollution says that index value of 0-50 (micrograms per cubic meter air) is excellent, 51-100 is good, 101- 150 is lightly polluted. "If the PM10 is more than 150, then it is alarming. If PM 10 is up to 100, then it is satisfactory," said Dr Ajit Singh, respiratory allergy specialist, department of medicine, Sawai Man Singh (SMS) Hospital. He said, “The example of PM10 is dust particles, moulds and pollens. These particles easily reach upto the lungs to cause various diseases related to lungs and respiration." According to the health experts, PM10 particles can penetrate into the lungs .