In September 2016, the WHO also declared that India accounts for 75% of air pollution casualties and talking about the damage caused by rising levels of pollution across the world, especially South Asia, the UN children's agency UNICEF has said that almost one in seven children worldwide live in areas with high levels of outdoor air pollution, mostly in South Asia and their growing bodies are most vulnerable to damage.

Now, in a worrying statement issued by Greenpeace India in a report, Delhi tops the list of 20 most polluted cities in the country where 1.2 million deaths take place every year due to air pollution.

It has been acknowledged that ever since Diwali 2016, the air quality in Delhi and the National Capital Region (NCR) has been bordering on hazardous levels and it seems that an easy respite remains distant.

The Greenpeace report also claimed that none of the 168 cities it assessed complies with air quality standards prescribed by the World Health Organization (WHO).

According to the report, 1.2 million deaths take place every year in India due to air pollution, which is only a "fraction less" than that caused by tobacco usage, and three per cent of the GDP is lost due to air pollution.

The report said that only a "few" cities in southern India comply with air quality standards prescribed by the Central Pollution Control Board (CPCB) and pinpointed fossil fuels as one of the "main culprits" for the deteriorating air quality across the country.

"The top 20 most polluted cities have PM 10 levels between 268 g/m3 and 168 g/m3 for the year 2015. While, Delhi tops the list with 268 g/m3, it is followed closely by Ghaziabad, Allahabad, and Bareli in Uttar Pradesh; Faridabad in Haryana; Jharia in Jharkhand; Alwar in Rajasthan; Ranchi, Kusunda and Bastacola in Jharkhand; Kanpur in Uttar Pradesh; and Patna in Bihar with PM10 levels ranging from 258 g/m3to 200 g/m3," the report titled 'Airpocalypse' said.

The information was obtained through online reports and Right to Information applications from State Pollution Control Boards across India and assessment of air quality was done in 168 cities across 24 states and Union territories.

"This report shows that deadly air pollution is not a problem restricted to Delhi-NCR (National Capital Region) or even to India's metros. It is a national problem that is killing 1.2 million Indians every year and costing the economy an estimated 3 per cent of GDP.

"If the country's development is important, fighting air pollution has to be a priority," the report said.

The assessment of air pollution levels for Delhi highlighted that PM10 concentrations are 268 g/m3 for year 2015, which were at 4.5 times higher than the NAAQS (National Ambient Air Quality Standards) annual limit set by CPCB and about 13 times the annual limit set by WHO for PM10.

Detailed observation of the data suggests that PM10 levels have been very high throughout 2015 for Delhi with October to February being the severely polluted months when the PM10 concentrations even touched 500 g/m3.

Holding that India's air pollution has become a "public health and economic crisis", the report said the number of people dying prematurely every year was rising with the increasing pollution levels.

"Deaths due to air pollution are only a fraction less than the number of deaths caused by tobacco usage. Global Burden of Disease (GBD) has estimated that 3,283 Indians died per day due to outdoor air pollution in India in 2015, making the potential number of deaths due to outdoor air pollution in India in 2015 to 11.98 lakh," it said.

Elaborating about Delhi, the report said that it has been long established as the pollution capital of the world by WHO, 2014 and most of the debate on air pollution in India are still centered around Delhi.

"Air pollution is a national public health crisis as almost none of the cities have bothered to keep air pollution in check, making them unlivable.

"We are facing an apocalypse right now due to unbreathable air, deaths due to air pollution are only a fraction less than those due to use of tobacco yet authorities are laying a deaf ear to the numerous scientific reports that have set alarm bells ringing," said Sunil Dahiya, campaigner, Greenpeace India.

The most polluted cities are spread across the North India, starting from Rajasthan and then moving along the Indo-gangetic belt to West Bengal, the report said, asserting that a closer analysis of the data pinpoint to continued use of fossil fuels as the main culprit for the dangerous rise in the level of pollutants in the air across the country.

"India's pollution trends have been steadily increasing, with India overtaking China in number of deaths due to outdoor air pollution in 2015. India' s deteriorating air quality demands an urgent robust monitoring system," the report said.

Greenpeace said that the country's pollution reduction strategies needs to be much more "ambitious, systematic and with focused targets with clear timelines".

"Accountability and compliance mechanism should be in place, with no leniency towards the fossil fuel dependant sectors such as power and transport," it said.