With Delhi Atop List of PM2.5 Exposed Cities, Nitrogen Oxide Emissions Also Rise in South Asia
The Wire Staff
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New Delhi: South Asia has some of the world's only areas where nitrogen dioxide (NO2) levels are increasing, an analysis by State of Global Air (SOGA) has found.
SOGA is a research and outreach initiative that aims to provide meaningful information about air quality in the world.
It published a ‘snapshot’ of air quality in the South Asia region on Tuesday (September 12) that draws from a global air quality analysis it concluded last year.
The snapshot finds that while levels of NO2 – a pollutant belonging to the highly reactive nitrogen oxides (NOx) group of gases – have declined in North America, Western Europe and China over recent years, they have been increasing in South Asia.
This is “fuelled by large-scale programs to expand access to energy to households, expanding industries and increases in vehicle ownership,” it explains.
In India, major sources of NO2 are coal-based energy production, industrial processes and on-road transportation.
Exposure to the gas can irritate the airways, aggravate existing respiratory diseases and increase the susceptibility to new ones, and heighten the risk of asthma development in children.
According to data from 2019, Bengaluru and Hyderabad top the list of major South Asian cities in terms of population-weighted NO2 exposure, SOGA said.
NO2 is also a key marker for traffic-related air pollution, the snapshot said. Photo: PTI.
It added that although South Asia stands out for the increase in its NOx emissions, NO2 emissions are low here compared to other regions in the world, and some countries in South Asia have NO2 quality standards in line with interim targets recommended by the WHO.
It cited a policy action from India, namely the Union government moving directly from the BS-IV emission norms to BS-VI, as an example of an initiative that will significantly reduce NOx emissions and bring “clean air dividends in the next decade”.
“In India, addressing source-specific emissions (for example, transportation) have begun to show dividends. In fact, satellite-based estimates indicate that NO2 levels may be beginning to decline in some Indian cities,” the snapshot also said.
As for another major air pollutant, PM2.5, SOGA noted that exposure it to remains high in South Asian cities. Less than 1% of these cities meet the WHO's PM2.5 guidelines, it said.
A list it provided of major South Asian cities with the most population-weighted PM2.5 exposure as of 2019 had Delhi and Kolkata in the first and second positions respectively.
The same two cities topped the SOGA's list for major cities across the world. Beijing came in at a farther ninth and Mumbai clocked in at 14th.
PM2.5 is any particulate matter that has a maximum width of 2.5 micrometres (0.0025 mm). The majority of air pollution deaths are associated with PM2.5.
SOGA's snapshot said that 34% of deaths in South Asia's 20 most populated cities are linked to exposure to PM2.5, and that Indians lose 1.5 years of their lives to PM2.5 pollution.
A study by the University of Chicago Energy Policy Institute last month said that particulate pollution takes 5.3 years off the lifespan of an average Indian, and that if India were to reduce particulate pollution to meet the WHO guideline, Delhiites stand to gain close to 12 years in life expectancy.
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