The World Health Organisation (WHO), in its first-ever update since 2005, has tightened global air pollution standards in recognition of the emerging science in the past decade that the impact of air pollution on health is much more serious than earlier envisaged.
The move does not have an immediate effect in India as the National Ambient Air Quality Standards (NAAQS) do not meet the WHO’s existing standards. The government has a dedicated National Clean Air Programme that aims for a 20% to 30% reduction in particulate matter concentrations by 2024 in 122 cities, keeping 2017 as the base year for the comparison of concentration. These are cities that do not meet the NAAQS when calculated from 2011 to 2015.
However, experts say the WHO move sets the stage for eventual shifts in policy in the government towards evolving newer stricter standards.
“This will soon become part of policy discussions — much like climate targets to reduce greenhouse gas emissions keep getting stricter over time — and once cities and States are set targets for meeting pollution emission standards, it could lead to overall changes in national standards,” said a senior official, who is part of a high- level commission to monitor air quality standards. The person declined to be identified as he is not authorised to speak to the media.
The upper limit of annual PM2.5 as per the 2005 standards, which is what countries now follow, is 10 microgram per cubic metre. That has now been revised to five microgram per cubic metre. The 24-hour ceiling used to be 25 microgram but has now dropped to 15. The upper limit of PM10, or particulate matter of size exceeding 10 microgram, is 20 microgram and has now been revised to 15, whereas the 24-hour value has been revised from 50 to 45 microgram.
India’s NAAQs — last revised in 2009 — specify an annual limit of 60 microgram per cubic metre for PM10 and 100 for a 24-hour period. Similarly it’s 40 for PM 2.5 annually and 60 on a 24-hour period. There are also standards for a host of chemical pollutants including sulphur dioxide, lead and nitrogen dioxide.
Environmental organisation Greenpeace, in a statement, said the new guidelines meant that among 100 global cities, Delhi’s annual PM2.5 trends in 2020 was 16.8 times more than the WHO’s revised air quality guidelines, while Mumbai’s exceeded eight-fold, Kolkata’s 9.4, Chennai’s 5.4, Hyderabad’s 7 and Ahmedabad’s 9.8.
“WHO’s new Air Quality Guidelines are an evidence-based and practical tool for improving the quality of the air on which all life depends. I urge all countries and all those fighting to protect our environment to put them to use to reduce suffering and save lives,” WHO Director-General Tedros Adhanom Ghebreyesus said in a statement.
Every year, exposure to air pollution is estimated to cause 7 million premature deaths and result in the loss of millions more healthy years of life.
Severe health crisis
“Air pollution is a severe health crisis and WHO’s revised air quality guidelines bring back the focus to the issue,” said S.N. Tripathi, Professor, IIT Kanpur & Steering Committee Member, National Clean Air Programme, India.