India recorded the world’s highest annual average concentration of PM 2.5 exposure in its air in 2019, according to the State of Global Air 2020 (Soga 2020) report released on Wednesday, extending to a decade the rising streak of the common air pollutant that has emerged as a respiratory health risk in the Capital and other cities.
According to the report, India was followed by Nepal, Niger, Qatar and Nigeria in exposure to PM 2.5, which are fine, inhalable particulate matter with diameters that are generally 2.5 microns, or about 30 times smaller than a strand of human hair.
India has been recording an increase in PM 2.5 pollution since 2010, said the report. The Central Pollution Control Board (CPCB)’s 2019 report indicates that the national average PM 2.5 concentrations has recorded a rising trend in the past three years owing to an increasing number of vehicles on the roads and re-suspension of natural dust.
Out of 20 most populous countries, 14 have recorded a gradual improvement in air quality but India, Bangladesh, Niger, Pakistan and Japan are among countries that have recorded at least a modest increase in air pollution levels measured by PM 2.5 content, said the report.
The report comes on top of others showing India to be one of the countries with the world’s worst air quality. Two-thirds of the most polluted cities, or 21 out of 30, are in India, and Delhi has the worst air among all national capitals, according to the 2019 World Air Quality Report by IQAir AirVisual.
PM 2.5 pollutants, made up of hundreds of chemicals, are emitted into the air by construction sites, unpaved roads, fields, and smokestacks or fires, and by power plants, factories and automobiles. They can enter the blood stream via the respiratory system to travel throughout the body, causing health problems such as asthma, lung cancer and heart disease.
“We need to read the complete report to be able to respond. But we can say that PM 2.5 standards were set only in 2009 following which monitoring began. So, we do not have trends for the entire decade as monitoring has gradually improved. Also, it’s not possible to say that the country is seeing a decline or rise in pollution levels. Some cities are improving while some cities are also showing fluctuating trends,” said a senior CPCB official.
Union environment minister Prakash Javadekar has said at various forums that Delhi’s air has improved significantly since 2016. He said in the Lok Sabha last year that the government would resolve the toxic air pollution problem in Delhi in less than 15 years — the time Beijing took to stanch a similar problem.
“Satellite data of the past 10 to 15 years shows there is an overall increase in air pollution levels. But in the past two years we are seeing a marginal improvement based on satellite data. We are studying what could be the factors leading to this improvement. Is it meteorology or a reduction in emissions also? We may publish a paper on our findings soon,” said Sagnik Dey, associate professor at Indian Institute of Technology-Delhi.
“In India, we do not have India-specific risk function which assesses how much of a risk, say air pollution, poses to developing various diseases. India should now do those long-term studies. The composition of particulate matter also has a huge impact on health… like is it dust or industrial emissions… so health impacts may vary by region. The bottom line is that exposure to PM 2.5 is very high in India.” he added.
Dey said the National Clean Air Programme, which aims to reduce the concentration of PM2.5 and PM10 (coarse pollution particles) in 102 so-called non-attainment cities by 20% to 30% by 2024 from the 2017 annual average levels, will be crucial.
Soga, released by the US-based Health Effects Institute and Global Burden of Disease project, uses both data from ground monitors and satellite data to make its assessments. To estimate the annual average PM2.5 exposure, scientists at the latter link the concentrations in each block (they divide the globe into blocks or grids) with the number of people living within each block to produce a population-weighted annual average concentration.
Out of 87 health risk factors assessed by the team based on the total number of deaths caused in 2019, air pollution emerged as the fourth highest risk globally, preceded by high systolic blood pressure, tobacco and dietary risks. But in India, air pollution is the highest risk factor because of the huge burden of premature deaths it contributes to.
India is also among the top 10 countries with the highest ozone (O3) exposure in 2019. Qatar recorded the highest O3 exposure followed by Nepal and India. Among the 20 most populous countries, India recorded the highest increase (17%) in O3 concentrations in the past 10 years.
On average, global exposure to ozone increased from about 47.3 ppb (parts per billion) in 2010 to 49.5 ppb in 2019. O3 is a major respiratory irritant that is not released directly into the air but is formed in a complex chemical interaction between nitrogen oxide (NOx) and volatile organic compounds in the presence of sunlight. NOx is emitted from the burning of fossil fuels (oil, gas, and coal) in motor vehicles, power plants, industrial boilers, and home heating systems.
The one silver lining for India is that the country managed to reduce the number of people exposed to household air pollution. China reduced the percentage of its population exposed to household air pollution from 54% to 36%, while India reduced its percentage from 73% to 61% over the past decade.
Since 2010, more than 50 million fewer people have been exposed to household air pollution. The Pradhan Mantri Ujjwala Yojana, under which free cooking gas connections are provided to poor households, and other schemes have helped to dramatically expand access to clean energy, especially in rural areas, the Health Effects Institute said in a statement.
“At this time, the data indicates that there was a modest increase in outdoor PM2.5 levels in India over the last decade. We know from experience elsewhere that the air pollution problem is unlikely to be solved in the short-term,” said Pallavi Pant, a scientist at Health Effects Institute.
“With the National Clean Air Programme and introduction of BS-VI (Bharat Stage-VI) emission standards, India has begun to take steps towards improving air quality, and it is critical that the efforts are continued and expanded over the next few years in order to see improvements in air quality,” she said.
TOP 5 countries with highest population weighted annual PM 2.5 exposure (in micrograms per cubic metres):