For Fourth Year in a Row, New Delhi Is Capital City With Worst Air

  • New Delhi is the capital city with the most polluted air for the fourth year in a row, a new report has found.
  • India is also one of the top five countries with the worst air, and is home to 12 of the 15 most polluted cities in central and south Asia.
  • The country desperately needs more air quality monitoring stations and a more effective pollution control plan.

Kochi: For the fourth consecutive year, New Delhi has retained its position as the capital city with the most polluted air. This is according to the World Air Quality Report 2021 released on March 22 by IQAir, a Swiss company that tracks air quality in real time.

India is also among the top five countries with the world’s lowest air quality. Twelve of the 15 cities in central and south Asia with the worst air in 2021 were in India. While the report said the number of air quality monitoring stations in India had increased, the country still only has a low 800-odd stations.

PM2.5 particles – inhalable motes less than 2.5 micrometres (µm) wide – are mostly emitted when fossil fuels are combusted, from factories, vehicular engines, trash fires, etc.

It has bad effects on the environment and health. According to one recent study, unsafe levels of PM2.5 are responsible for around 4 million people dying before they otherwise might have. A quarter of these deaths occur in India.

The Central Pollution Control Board (CPCB), India’s apex statutory body for pollution control, stipulates that the annual average PM2.5 level over an area should’t exceed 40 µg/m3. The WHO however has an 8x more stringent limit, of 5 µg/m3.

Bad air

The 2021 World Air Quality Report compiled PM2.5 data from 6,475 cities in 117 countries. It accounted for data collected by regulatory and air-quality monitoring stations operated by governments, non-profit organisations, research institutions, educational facilities, companies, and citizen scientists.

Its report stated that New Delhi continued to be the capital city with the world’s most polluted air in 2021 – for the fourth straight year. PM2.5 concentration over the city was 96.4 μg/m3. This was a 14.6% increase from the year before.

India was also found to have the world’s fifth-worst air overall. Its annual average PM2.5 concentration (weighted by population) also increased – to 58.1 μg/m3 in 2021 from 51.9 μg/m3 in 2020. This increase ended the country’s three-year improvement in PM2.5, the report said.

India and Pakistan also experienced “the worst air quality” in central and south Asia, with 48% and 67% respectively of their cities reporting PM2.5 concentrations greater than 10x the permitted WHO levels.

The top 15 most polluted regional cities in central and south Asia are also in India and Pakistan. Twelve are in India alone: Bhiwadi, Ghaziabad, Delhi, Jaunpur, Noida, Bahawalpur, Bagpat, Hisar, Faridabad, Greater Noida, Rohtak and Lucknow. No city in India met the WHO limits.

India struggles

The report noted that the amount of publicly available data from monitoring stations seems to be increasing. This is in line with reports of more stations being installed in the country.

In July 2021, Jammu & Kashmir reportedly received its first real-time air monitoring station in Srinagar. On December 29, 70 air and noise monitoring stations went live across West Bengal. And per the PCB, as of mid-September 2021, 804 stations were operational stations in 344 cities and towns in 28 states and six Union territories.

But with its large area, population and increasing air pollution, experts have estimated India needs 1,600-4,000 monitors.

The government launched the National Clean Air Programme (NCAP) in 2019 to reduce particulate matter concentration by at least 20% by 2024 over 100 of India’s most polluted cities. But this and other policies to curb air pollution haven’t borne fruit. The reasons range from underfunding to treating pollution as if it recognises borders.

India has been struggling for a long time to control its PM2.5 concentration. In Varanasi, Prime Minister Narendra Modi’s Lok Sabha constituency, the atmospheric concentration of PM2.5 and nitrogen dioxide have been far higher than the permissible levels specified by the CPCB for three years in a row, The Wire Science reported in December.

Studies have shown that biomass burning, which is one source of PM2.5 when farmers burn crop stubble in their fields, contributes to fully 40% of air pollution over Delhi around the winter months, Vijay Kanawade, an atmospheric scientist at the University of Hyderabad, said. The topography of the area and atmospheric conditions in winter further amplify air pollution in this time, he added, as do emissions from burning fossil fuels.

According to him, reducing primary emissions is key – as is isolating the effects of each factor (local and regional sources and different types of emissions) on the overall pollution. This is because air pollution is not just a local problem, but a regional, even global, one that transcends boundaries.

We also need more monitoring stations for more robust data, he added, because this will help identify primary and secondary sources, and their interactions.

“It is also not just an urban problem anymore but a rural one too. So we definitely need more monitoring stations across the country.”