WHO revises air quality guidelines, recommends stringent levels for key pollutants

Vibha Sharma

Tribune News Service

New Delhi, September 22

The World Health Organisation on Wednesday revised its global air quality guidelines, recommending more stringent standards for key pollutants—PM 2.5 and PM 10, ozone (O3), nitrogen dioxide (NO2) sulfur dioxide (SO2) and carbon monoxide (CO). The WHO Global Air Quality Guidelines (AQGs), which is the first update since 2005, provide recommendations on air quality guideline levels as well as interim targets.

According to the new guidelines, the PM 2.5 norms for 24-hour average is now 15 micro;g/m3 instead of 25 micro;g/m3 (in 2005) and 5 micro;g/m3 annual instead of 10 micro;g/m3 (in 2005).

However, even at the current relaxed standard, at 40 ug/m3 for annual PM 2.5 averages in India versus WHO’s 2005 annual limit of 10 ug/m3 most Indian cities failed to meet even those levels, says Prof S N Tripathi from the IIT-Kanpur and Steering Committee Member, National Clean Air Programme (NCAP), calling for “revising India’s air quality standards to make them more stringent”.

The NCAP has a target to reduce 20-30% of PM 2.5 and PM 10 concentrations by 2024, taking levels in 2017 as the base year.

According to Prof Tripathi there is a body of scientific evidence to prove that air pollution is leading to severe health impacts and 90% of the entire global population is breathing polluted air.

“Air pollution is a severe health crisis and WHO’s revised air quality guidelines bring back the focus to the issue. There are no two ways about the need for revising India’s air quality standards to make them more stringent.

“Even at the current relaxed standard of 40 ug/m3 for annual PM2.5 averages in India vs WHO’s 2005 annual limit of 10 ug/m3, most Indian cities failed to meet even those levels. In parallel, we have to strengthen our health data and revise the National Ambient Air Quality Standards accordingly.

“Raw health data is required to conduct a large range of health studies vis-a-vis air pollution impacts for India’s varied demography, exposure and differing PM 2.5 composition. A single exposure prevention response will not suit the Indian population,” he adds.

Dr Ravindra Khaiwal from the Environment Health department of the PGI Chandigarh says the stringent standards will bring the focus on strict and swift action for better air quality.

“Air pollution has become a major risk factor for premature mortality and morbidity. Meeting the new WHO Global Air Quality Guidelines seems a challenge, but under NCAP India is committed to minimise 20-30% of cities’ air pollution. Collective efforts are needed to mitigate the air pollution and gain in terms of better human health and climate,” he said.

According to WHO, air pollution is one of the biggest environmental threats to human health, alongside climate change and new AQGs provide clear evidence of the damage air pollution inflicts on human health, at even lower concentrations than previously understood.

With annual mean of 40 ug/m3 of PM 2.5, India ranks third after Bangladesh and Pakistan in the pollution ranking of the Asian countries according to the 2005 guidelines

In 2019, more than 90% of the global population lived in areas where concentrations exceeded the 2005 WHO AQG level of 10 micro;g/m3, it says.

With the 2021 AQG levels being lower, there is bound to be an increase in the attributable health burden in all countries, it adds.

According to Greenpeace, among 100 global cities, Delhi’s annual PM 2.5 trends in 2020 was 16.8 times more than WHO’ s revised air quality guidelines of 5 ug/m3, while Mumbai’s exceeded 8-fold, Kolkata 9.4, Chennai 5.4, Hyderabad 7 fold and Ahmedabad exceeded 9.8 fold.

“Calculating premature deaths and financial losses due to air pollution for 10 cities across the world, Delhi accounted for the maximum number of deaths, 57,000 in 2020 and 14% of GDP loss due to air pollution. While GDP percentage share was highest amongst cities, the cost per capita was low in comparison to other cities which have higher per capita income and accumulated losses,” it says.

The WHO estimates show that around 7 million premature deaths, mainly from noncommunicable diseases, are attributable to the combined effects of ambient and household air pollution.