The World Health Organization (WHO) on Wednesday revised its global air quality guidelines, hoping that the new air quality levels would protect human populations by reducing the levels of some key air pollutants, some of which also contribute to climate change.
These updated guidelines come at a pivotal time. Incepted in 1987, these guidelines were first updated in 1997. The last update to the AQGs was in 2005. Since then, according to the WHO, there has been a marked increase in the quality and amount of evidence that shows how air pollution affects different aspects of human health. Hence, after a systematic review of the evidence, several of the updated AQG values are now lower than 15 years ago, a WHO information note explains.
The new guidelines recommend air quality levels for six pollutants, where evidence has advanced the most on health effects from exposure. When action is taken on these so-called classical pollutants – particulate matter (PM 2.5 and PM 10), ozone (O3), nitrogen dioxide (NO2) sulfur dioxide (SO2) and carbon monoxide (CO), it also has an impact on other damaging pollutants, the note explains.
Air pollution is now easily the biggest environmental threat to human lives after climate change. In 2019, more than 90% of the global population lived in areas where concentrations exceeded the 2005 WHO AQG level of 10 μg/m3. With the 2021 AQG levels being lower, there is bound to be an increase in the attributable health burden in all countries. 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.
“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, Dr Tedros Adhanom Ghebreyesus said in a press release. “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.”
How can these guidelines be useful?
The AQGs provide evidence-informed guidance to protect public health from air pollution. While the guidelines are not legally binding recommendations, they can be used as a key, evidence-based reference tool to help decision-makers around the world in setting legally binding standards and goals for air quality management at the international, national and local level.
Academic researchers and national and local authorities working in the field of air pollution can also find the guidelines useful for planning research and impact assessments. More importantly, they can also be used as an advocacy tool for protecting public health from air pollution, by civil society and academic groups.
Apart from offering additional AQG levels, such as for peak season O3 and 24-hour NO2 and CO, as well as some new interim targets; the updated guidelines also provide new good practice statements on the management of certain types of PM (that is, black carbon/ elemental carbon, ultrafine particles, and particles originating from sand and dust storms).
The new guidelines and good practices could be particularly key for the South Asia region, where air pollution levels have been consistently high. India, which last revised its air pollution standards in 2009, is home to some of the most polluted cities in the world. According to Greenpeace, among the 100 most populous global cities, Delhi's annual PM2.5 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 seven-fold and Ahmedabad exceeded 9.8 fold.
“It’s been more than a decade since India notified the National Ambient Air Quality Standards in 2009 and a lot of new evidence on impacts of different pollutants on human health at lower pollution levels have come into existence, necessitating the Indian government to revise the standards similar to WHO’s action,” says Sunil Dahiya, Analyst, Centre for Research on Energy and Clean Air (CREA), an independent research organisation that works on the trends, causes, health impacts and solutions to air pollution. “The good thing is that India is already working on revising the standards; we just need to make sure we make use of evidence gathered by WHO and others on increasing and severe health impacts of pollutants at lower levels and try to aim towards moving closer to WHO prescribed levels for pollutants.”