Much has been made of Mumbai's air pollution in recent months being worse than Delhi's notorious pollution. Delhi Chief Minister Arvind Kejriwal even tweeted a global ranking, in which Mumbai was placed second, saying that after a long time the national capital was not in the list of the world's most polluted cities.
That was on a day, however, when the Delhi region benefited from strong winds blowing away much of the pollutants in the air. The ranking was by a Swiss firm, IQ Air, and is updated frequently.
While Mumbai's air quality has indeed deteriorated, new data from IQ Air shows different and worrying trends about the real picture.
In this NDTV exclusive, data shows that the national capital's pollution levels have been consistently twice the level of India's financial capital, Mumbai.
This is based on the measurement of PM 2.5 pollutant levels, which is the microscopic and lethal particulate matter (PM) that can beat the human body's defences and embed itself deep in the lungs and thereon into other organs.
The new data (table below) shows how Delhi's air pollution level has been higher than Mumbai's every month in 2022, particularly in November-December, which was when Mumbai's air pollution first made headlines for surpassing the national capital's.
And it's not just recent months. For the past four years, Delhi's annual average of PM 2.5 has been an average of 95 micrograms per cubic metre, whereas Mumbai's has been 45.
The metropolis on the coast usually benefits from the sea breeze clearing the city of pollution, mainly from vehicles, construction and road dust. However, this winter, doctors have reported a spurt in patients with respiratory infections, especially among children.
The data (table below) shows that PM 2.5 levels in November and December rose by 18 per cent over the previous year. The government's data reportedly shows an even steeper increase of over 60 per cent last November.
The data, which is presented alongside the World Health Organisation's guideline (table below) for clean air, shows just how far off both cities are from the safe PM 2.5 limit of only 5 micrograms per cubic metre.
For last November and December, Delhi exceeded the WHO's safe air quality standard by almost 40 times, and Mumbai by about 16 times - both very hazardous to health.
Source: IQ Air