The World Health Organization (WHO) today released a revised global air quality guideline, which lists six pollutant categories — particulate matter (PM), ozone (O3), nitrogen dioxide (NO), sulphur dioxide (SO2) and carbon monoxide (CO), and more stringent limits were announced for this. Since the last 2005 WHO global update, there has been a significant increase in the evidence for how air pollution affects various aspects of health. Taking cognizance of these factors, the WHO has adjusted almost all air quality criteria downward, warning that exceeding the level of the new air quality guideline is associated with significant risks to health. Also, following them can save millions of lives.
“Since the last update in 2005, a huge new body of evidence has accumulated, and it shows the extent to which air pollution affects all parts of the body, from the brain to the first growing baby in the mother’s womb, at concentrations lower than that,” the WHO Director-General insisted. The revised WHO guidelines set an annual PM 2.5 average of 5 ug/m3, bringing it down from the 2005 limit of 10 ug/m3. The annual average of PM 10 is now 15 µg/m3 as against 20 µg/m3 earlier. NO2 levels, which are mainly due to vehicular emissions, have been revised upwards to 10 ug/m3 in 2005 from 40 ug/m3.
“These new guidelines will have major implications for public health. They provide a practical tool for improving air quality around the world, and provide a strong evidence-base for developing national and local air quality standards,” said Ghebreyesus. Although these guidelines are not legally binding, the WHO recommendations on air quality are an evidence-informed tool for policymakers to guide legislation and policies, to reduce levels of air pollutants and reduce the burden of disease. to reduce what occurs in the world as a result of exposure to air pollution. “It is common knowledge that the lower the exposure, the healthier the outcome. Under new air quality guidelines, WHO calls for increased efforts to control particulate concentrations in the air by lowering PM 2.5 and 10 exposure levels.But for countries like India, it is a huge challenge to meet these guidelines. I hope that the efforts of all the stakeholders will be intensified so that sincere efforts can be made towards the revised levels,” Dr. Arun Sharma, Director, National Institute for Implementation Research of Non-Communicable Diseases, ICMR said.
Low- and middle-income countries such as India have experienced inequalities in air pollution exposure due to large-scale urbanisation and economic development, which is largely powered by fossil fuels, resulting in a disproportionate burden of disease and mortality for its population. India last revised its national ambient air quality standards in 2009, setting annual averages for PM2.5 (40 ug/m3), PM10 (60 ug/m3), and NO2 (40 us/m3) — in which the WHO’s 2005 guidelines were more relaxed than those of other South Asian countries such as Bangladesh, Pakistan, and Nepal. The WHO guidelines, also often referred to as “safe levels”, ties the assumption that they will reduce the risk of illness or death. In 2013, outdoor air pollution and particulate matter were classified as carcinogenic by the WHO’s International Agency for Research on Cancer (IARC).
Sunil Dahiya, an analyst at the Center for Research on Energy and Clean Air, stressed on the need for India to revise air quality standards in view of the rising pollution levels in the country. “It has been more than a decade since India notified the National Ambient Air Quality Standards in 2009 and a lot of new evidence has come into existence on the effects of various pollutants on human health at low pollution levels: leading the Indian government to the WHO uniform standards of action need to be revised,” Dahiya said. He further added, “The good thing is that India is already working on revising the standards, we just need to make sure that we look at the evidence gathered by WHO and others on the increasing and serious health effects of pollution. Try to aim for low levels and close to the WHO set levels for pollutants.”
PM 2.5 and PM 10 are both capable of penetrating deep into the lungs, but PM 2.5 can also enter the bloodstream, primarily having cardiovascular and respiratory effects, and affecting other organs as well. PM is mainly generated by the combustion of fuels in various sectors, including transportation, energy, households, industry, and agriculture. While these guidelines are not legally binding on countries, new recommendations for air quality standards, if adopted by nations, could save millions of lives and contribute to climate change. In 2020, 92 out of 100 global cities exceeded WHO’s revised 2021 air quality guidelines, including 5 Indian cities. Delhi’s annual PM 2.5 trend in 2020 was 16.8 times higher than WHO’s 2021 guidelines of 5 ug/m3, while Mumbai’s was 8 times, Kolkata 9.4, Chennai 5.4, Hyderabad 7 times and Ahmedabad 9.8 times.
SN Tripathi, a professor at the Indian Institute of Technology Kanpur and a steering committee member of the National Clean Air Program, said there are no two ways about the need to revise India’s air quality standards to make them more stringent. “Even at the current comfort standard of 40 ug/m3 for the annual PM 2.5 average in India versus the 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 national ambient air quality standards accordingly. India’s diverse demographics, exposures and varying PM 2.5 composition require raw health data to conduct a large range of health studies along with air pollution impacts. The single risk containment response will not be suited to the Indian population,” he said. Air pollution is considered the greatest environmental threat to health, and it disproportionately affects vulnerable populations: 91% of deaths from ambient air pollution occur in low-income and middle-income countries. In India, 1,16,000 infant deaths in 2019 were due to air pollution, while coal burning caused 100,000 deaths and ambient air pollution killed 16.7 lakh Indians. Children are also particularly vulnerable, as exposure to air pollution in childhood can reduce lung capacity. Globally, around 15% of deaths from COVID-19 are linked to PM 2.5 air pollution.
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 may include decreased lung growth and function, respiratory infections, and aggravated asthma. In adults, ischaemic heart disease and stroke are the most common causes of premature death due to outdoor air pollution, and evidence of other effects such as diabetes and neurodegenerative conditions is also emerging. This puts the burden of disease caused by air pollution on par with other major global health risks, such as unhealthy diets and tobacco smoking. Air pollution is one of the biggest environmental threats to human health along with climate change. Improving air quality can enhance efforts to mitigate climate change, while reducing emissions will improve air quality. By striving to achieve these guideline levels, countries will be both protecting health as well as mitigating global climate change.