New Delhi gained the notorious distinction of being labelled the most polluted capital city in the world in the year 2023.
As residents breathed air that is nearly 20 times the international safe standard, according to data from Swiss firm IQAir revealed on Tuesday, which also ranked India as the world’s third most polluted country.
With an annual population-weighted PM2.5 of 92.7µg/m3, New Delhi edged out Dhaka (80.2 µg/m3) to become the world’s most polluted national capital. Burkina Faso’s capital Ouagadougou, with a population-weighted PM2.5 of 46.6µg/m3, was a distant third on the list.
Of the 50 most polluted cities in the world, 42 were Indian — up from 39 in 2022, with Begusarai (118.9µg/m3) in Bihar occupying the top spot, followed by Guwahati (105.4µg/m3).
The larger Union territory of Delhi recorded an average PM2.5 concentration of 102.1µg/m3 in 2023 making it the third most polluted city globally. The smaller capital of New Delhi was on the sixth spot globally.
Across the National Capital Region (NCR), Delhi was followed by Greater Noida (88.6µg/m3) as the most polluted, ranking 11th in the list of the world’s most polluted cities. Gurugram (84µg/m3) was next at 17th. In 2022, after Delhi, Ghaziabad was the most impacted (88.6).
The findings were part of the World Air Quality Report 2023 and are concurrent with the annual spectre of air pollution that engulfs the National Capital Region around Diwali every year and extends well into the winter. Of late, the residents of India’s capital are not even spared the onslaught of pollution even in the thick of winter.
In the 2022 iteration of the report, New Delhi ranked as the second most polluted capital in the world behind Chad’s N’Djamena (89.7µg/m3). In 2021, it was again the most polluted capital city in the world with an annual average of 85µg/m3, ahead of Dhaka (78.1µg/m3).
“PM2.5 levels in the National Capital Territory, Delhi, rose by 10% in 2023, with levels peaking in November which saw a monthly average of 255 µg/m3,” the report said.
To be sure, some regions, including Chad, were dropped from the list due to lack of sufficient data.
Delhi usually goes through three fortnights where the AQI is routinely in the severe zone: The first half of November, the second half of December, and then mid-January. During the first phase, the toxicity is fuelled largely by smoke from farm stubble fires in Punjab. The second and third phases are, however, down largely to local sources of pollution like vehicular and industrial emissions, which are in turn worsened by nearly still winds and dipping temperatures.
According to IQAir’s report, vehicle emissions are responsible for 40% of PM2.5 emissions in the city.
The report looked at data from more than 30,000 air quality monitoring stations across 7,812 locations in 134 countries, territories, and regions and tracked PM2.5 concentrations – fine particulate aerosol particles measuring up to 2.5 microgrammes per cubic metre – to understand the exposure to the people living in the specific area and determine a population-weighted exposure level.
Over the last decade, both the central and state governments have introduced measures to help combat the pollution.
In 2016, the Centre approved the Graded Response Action Plan (Grap) for Delhi-NCR — a series of emergency-level measures that are enforced every winter, based on the prevailing air quality. In 2021, the Commission for Air Quality Management (CAQM) for NCR was constituted to enforce measures and bring down pollution in Delhi.
Exposure to PM2.5 air pollution can exacerbate numerous health conditions, including but not limited to asthma, cancer, stroke, and lung disease. It can also lead to impairment of cognitive development in children, and complication in existing illnesses including diabetes.
The report noted that northern India and Delhi struggle with smoke from crop burning, vehicle emissions, coal burning, waste burning, and biomass burning for heat and cooking.
“Annual crop burning in northern India and neighbouring Pakistan regularly results in Delhi experiencing emergency-level air quality days,” it said.
Mullanpur (100.4µg/m3) in Punjab and Lahore in Pakistan (99.5µg/m3) ranked number four and five, respectively.
India’s annual PM 2.5 was 54.4µg/m3 — behind only Pakistan (73.7µg/m3) and Bangladesh (79.9µg/m3), the report said.
In 2022, when the country ranked 8th in the list of most polluted countries, India’s annual PM 2.5 average was 53.3µg/m3.
Chad (89.7 µg/m3) was the most polluted country in 2022, followed by Iraq (80.1µg/m3) and Pakistan (70.9 µg/m3). The other countries ahead of India were Bahrain, Bangladesh, Burkina Faso and Kuwait.
In the latest report, while Chad is missing due to lack of air quality data, Iraq, Bahrain, Burkina Faso and Kuwait have shown an improvement.
There were nine new entrants in the top 50 most polluted cities list, on account of data being available for the first time in 2023.
These included eight Indian cities: Goshaingaon in Assam (ranked 9), Samastipur in Bihar (15), Hanumangarh in Rajasthan (23), Bandhwari in Haryana (32), Baghpat in Uttar Pradesh (33), Mushalpur in Assam (45), Dhaulpur in Rajasthan (49) and Ganganagar in Rajasthan (50).
Experts said that the high number of Indian cities featuring in the most polluted list indicated that pollution levels across the country were high.
“This shows that we possibly have high pollution across the country, but don’t have adequate ambient air quality stations spread so far. Begusarai, which has been ranked as the world’s most polluted city, also is a hub of fossil-fuel based industries. This shows the possible impact such industries can have on the air,” said Avinash Chanchal, campaigner at Greenpeace India.
The only city from southern India that found a mention on the list was Vayushaktinagar in Hyderabad, ranked 60 among the most polluted Indian cities.
In 2022, Lahore in Pakistan (97.4), Hotan in China (94.3) and Bhiwadi in Rajasthan (92.7) were the world’s most polluted cities, with Delhi ranking fourth overall (92.6). Interestingly, in the 2023 rankings, Bhiwadi is down to 31 rank overall, recording an average concentration of 77.1.
The report said only seven — Australia, Estonia, Finland, Grenada, Iceland, Mauritius, and New Zealand — out of the 134 countries analysed were able to meet the World Health Organization (WHO) annual PM 2.5 average of 5µg/m3 or less.
“IQAir’s annual report illustrates the international nature and inequitable consequences of the enduring air pollution crisis. Local, national, and international effort is urgently needed to monitor air quality in under-resourced places, manage the causes of transboundary haze, and cut our reliance on combustion as an energy source,” said Aidan Farrow, senior air quality scientist, Greenpeace International.
“In 2023, air pollution remained a global health catastrophe. IQAir’s global data set provides an important reminder of the resulting injustices and the need to implement the many solutions that exist to this problem,” he added.
According to the report, India’s overall PM 2.5 concentration was 10 times higher than the WHO permissible limit, putting nearly 1.36 billion people at risk of health hazards. “Furthermore, 1.33 billion, or 96% of the population, experience PM2.5 levels more than seven times the WHO annual PM2.5 guideline,” the report said.
Anumita Roychowdhury, executive director, research and advocacy at the Centre for Science and Environment (CSE) said the latest rankings once again highlight how air quality continues to remain challenging in rapidly motorising and urbanising Indian cities.
“To fix this, we need transformative multisector action across all regions under the National Clean Air Programme for time bound reduction in pollution levels. While most global rankings happen based on the PM2.5 concentration, our NCAP programme is solely focused on evaluating performance of cities based on PM10 which diverts attention and resources towards dust control. This also shows that we need stronger strategies for controlling more harmful finer fraction of PM2.5 that comes largely from combustion sources,” she said.