India, Nepal ‘most exposed’ to deadly particle pollution

traffic jam in Delhi - main
Traffic jam in Delhi. Vehicular emissions are one of the main sources of particulate pollution in South Asia. Copyright: NOMAD (CC BY 2.0).

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  • Air pollution ‘fourth biggest’ global health risk after blood pressure, tobacco and diet
  • India, Nepal exceed WHO limits for particle pollution
  • Niger, Qatar and Nigeria occupy next three places, report says

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[NEW DELHI] India and Nepal have the highest concentration of deadly particle pollution in the world, and the problem is only getting worse, according to the State of Global Air 2020 report.  
Known as PM2.5, particles smaller than 2.5 micrometres in diameter – less than a 30th of the diameter of a human hair and capable of entering the bloodstream via the lungs – are emitted by vehicles, coal-burning power plants, industrial activity, waste burning, and other human activities such as cooking. 


The 21 October report put India on top of countries showing high exposure to PM2.5 concentration at 83.2 micrograms per cubic metre of air, followed closely by Nepal with 83.1 micrograms per cubic metre.
WHO’s Air Quality Guideline level for PM2.5 is only 10 micrograms per cubic metre. Niger, Qatar and Nigeria occupy the next top three places after Nepal.
“Long-term exposure to air pollution, especially PM2.5, is a serious but poorly recognised issue,” says Bhupendra Das, researcher on air quality at the Institute for Advanced Sustainability Studies, Potsdam, Germany and Tribhuvan University, Kathmandu, who was not involved in the study.
“South Asian countries — Bangladesh, India, Nepal and Pakistan — are most vulnerable.”
According to the report, exposure to high concentrations of PM2.5 over several years has been the most consistent and robust predictor of mortality from cardiovascular, respiratory, and other types of diseases


“Long-term exposure to air pollution, especially PM2.5, is a serious but poorly recognised issue. South Asian countries — Bangladesh, India, Nepal and Pakistan — are most vulnerable”

Bhupendra Das, Advanced Sustainability Studies and Tribhuvan University

The report calculates that in 2019, aerial pollutants over India contributed to over 1.67 million of the 6.67 million air pollution deaths worldwide.

It said India has been recording steadily increasing PM2.5 pollution over the past decade.

Nearly all of India’s 1.3 billion people live in areas where PM2.5 levels are higher than WHO guidelines. Nepal’s vast Himalayan landscapes notwithstanding, the country was not far behind, with 98 per cent of its 30 million population living in areas that exceed WHO standards.  

Das, from Potsdam’s Institute for Advanced Sustainability Studies, tells SciDev.Net that it is noteworthy that the report shows “the trend of ambient air pollution increasing in South Asia, whereas indoor or household air pollution seems to be declining”. 

“From my own studies, I can say that the increase in PM2.5 in South Asia is mainly due to vehicular emissions, solid waste open burning, crop residue open burning, coal-fired power plants, brick kilns, industrial activities, and other anthropogenic and natural sources,” Das says.

“It is important to note factors like lack of legal mandate to implement environmental policies, lack of action plan or strategies, lack of better air quality management plan, low-grade vehicle engines, insignificant proportion of efficient and smart technologies, and [the fact that] concerns and actions [are] limited to cities only,” Das says. 

The report — released by the US-based Health Effects Institute and the international research program Global Burden of Disease — relied on data from ground monitors and remote-sensing satellites to estimate average PM2.5 exposure.

Globally, of 87 health risk factors, air pollution stood fourth after high blood pressure, tobacco and diet.

India did, however, reduce the number of people exposed to household air pollution, mainly through subsidised distribution of clean cooking fuels. India reduced its population exposed to household air pollution from 73 per cent to 61 per cent over the past decade, while China achieved a corresponding reduction from 54 per cent to 36 per cent.

The good news is that although Asia, Africa and the Middle East saw the highest annual average exposures to PM2.5 last year, 14 out of the 20 most populous countries of the world experienced a drop in levels of the pollutant. But “countries with some of the highest exposures in the world — India, Pakistan, and Bangladesh — continue to see increases”, the report said.  

Globally, an estimated 476,000 infants died from exposure to air pollution in 2019. “Infants born in sub-Saharan Africa and South Asia have the highest rates of neonatal deaths attributable to air pollution, from 9,000 to 13,100 per 100,000 live births,” the report says.
Mukesh Sharma, professor and specialist in environmental engineering at the Indian Institute of Technology at Kanpur, India, who was not involved in the report, tells SciDev.Net that replacing wood, crop, coal and dung with LPG for cooking and elimination of diesel power generation were “soft options” to reduce chronic toxicity from PM2.5, which differs according to source.

A study that Sharma and colleagues conducted in Delhi, published April in Chemosphere, showed PM2.5 in road dust, vehicular emissions, coal, dung, wood and coal power plants having high toxicity because of the presence of heavy metals and also arsenic and carbon monoxide.

This piece was produced by SciDev.Net’s Asia & Pacific desk.