The World Health Organisation (WHO) in its first-ever update since 2005 has tightened global air pollution standards in a recognition of the emerging science in the last decade that the impact of air pollution on health is much more serious than earlier envisaged.
The move doesn’t immediately impact India as the National Ambient Air Quality Standards (NAAQS) don’t 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 don’t meet the NAAQS when calculated from 2011-2015.
Sets stage for eventual shifts in policy
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’s part of a high level commission to monitor air quality standards. The person declined to be identified as he isn’t 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 PM10, or particulate matter of size exceeding 10 microgram, upper limit is 20 microgram and has now been revised to 15 whereas the 24-hour value has been revised from 50 to 45 microgram.
Standards for a host of chemical pollutants
India’s NAAQs — last revised in 2009 — specify an annual limit of 60 microgram per cubic metre for PM 10 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 among100 global cities, Delhi’s annual PM2.5 trends in 2020 was 16.8 times more than WHO’s revised air quality guidelines, while Mumbai’s exceeded 8-fold, Kolkata 9.4, Chennai 5.4, Hyderabad 7 and Ahmedabad exceeded 9.8 fold.
“Air pollution is a threat to health in all countries, but it hits people in low- and middle-income countries the hardest,” WHO Director-General Tedros Adhanom Ghebreyesus said in a statement. “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.”
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. In children, this could include reduced lung growth and function, respiratory infections and aggravated asthma. In adults, ischaemic heart disease and stroke are the most common causes of premature death attributable to outdoor air pollution, and evidence is also emerging of other effects such as diabetes and neurodegenerative conditions. This puts the burden of disease attributable to air pollution on a par with other major global health risks such as unhealthy diet and tobacco smoking, the WHO noted.
Severe health crisis
“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,” said SN Tripathi, Professor, IIT Kanpur & Steering Committee Member, National Clean Air Programme, India.
Both PM2.5 and PM10 are capable of penetrating deep into the lungs but PM2.5 can even enter the bloodstream, primarily resulting in cardiovascular and respiratory impacts, and also affecting other organs. PM is primarily generated by fuel combustion in different sectors including transport, energy, households, industry and from agriculture. In 2013, outdoor air pollution and particulate matter were classified as carcinogenic by WHO’s International Agency for Research on Cancer (IARC).
