PCD inspected some petrochemical plants last summer following a complaint filed to it. Credit: PCD

Limits on key air pollutants toughened to protect people’s health from air pollution

The World Health Organization (WHO) has introduced the newly adjusted Global Air Quality Guidelines (AQGs) in a hope that this could help protect people’s health from air pollution better

WHO’s new guidelines have recommended air quality levels or pollution limits be lowered for six pollutants; be they particulate matter (PM), ozone (O₃), nitrogen dioxide (NO₂) sulfur dioxide (SO₂) and carbon monoxide (CO). Realising that this could be an uphill task for governments to adhere to, it has at the same time proposed interim targets (four targets) to facilitate stepwise improvement in air quality.

For particulate matter equal or smaller than 2.5 and 10 microns (µm) in diameter (PM2.5 and PM10 respectively), their 24-hour limits have been cut down from 25 to 15 micrograms per cubic meter at the utmost level, and from 50 to 45 µg/m3, respectively. At the same time, their annual limits have been adjusted from 10 to 5 µg/m3 and from 20 to 15 µg/m3, respectively. Thailand has set the 24-hour limit for PM2.5 at 50 µg/m3, and the annual limit for it at 25 µg/m3, thus standing beyond the limits even before the new adjustment by over half already.

The new adjustment, therefore, means a more widening gap between the global health agency’s recommendations and the legal limits set by the government and more ambition required to save people’s health.

PM is primarily generated by fuel combustion in different sectors, including transport, energy, households, industry, and agriculture. In 2013, outdoor air pollution and particulate matter were classified as carcinogenic by WHO’s International Agency for Research on Cancer (IARC), and since have gained particular attention.

PM2.5 and PM10 are cited as capable of penetrating deep into the lungs and PM2.5 can even enter the bloodstream, primarily resulting in cardiovascular and respiratory impacts, and also affecting other organs, according to this global health organisation.

WHO last issued the recommendation in 2005, but has decided to adjust the limits this year, given clear evidence of the damage air pollution inflicts on human health, at even lower concentrations than previously understood, according to the organization.

“Since the last 2005 global update, there has been a marked increase of evidence that shows how air pollution affects different aspects of health. For that reason, and after a systematic review of the accumulated evidence, WHO has adjusted almost all the AQGs levels downwards, warning that exceeding the new air quality guideline levels is associated with significant risks to health. At the same time, however, adhering to them could save millions of lives,” the organization pointed.

The Guidelines are not legally binding, but they are an evidence-informed tool for policy-makers to guide legislation and policies in order to reduce levels of air pollutants and decrease the burden of disease that results from exposure to air pollution worldwide, the organization noted.

Credit: WHO

Public health hazards

According to WHO, every year exposure to air pollution is estimated to cause seven million premature deaths and result in the loss of millions more healthy years of life. In children, WHO noted that 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, the organisation further noted.

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, said WHO, while adding the pollution is one of the biggest environmental threats to human health, alongside climate change.

“Air pollution is a threat to health in all countries, but it hits people in low- and middle-income countries the hardest,” said WHO Director-General, Dr. Tedros Adhanom Ghebreyesus. “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.”

Disparities in air pollution exposure are increasing worldwide, particularly among low-and middle-income countries as they are experiencing growing levels of air pollution because of large-scale urbanization and economic development that has largely relied on the burning of fossil fuels, the organization noted.

WHO Regional Director for Europe, Dr. Hans Henri P. Kluge said annually WHO estimates that millions of deaths are caused by the effects of air pollution, mainly from noncommunicable diseases. However, despite some improvements in air quality over the past three decades, millions of people continue to die prematurely, often affecting the most vulnerable and marginalized populations.

“Clean air should be a fundamental human right and a necessary condition for healthy and productive societies,” he said. “We know the magnitude of the problem and we know how to solve it. These updated guidelines give policy-makers solid evidence and the necessary tool to tackle this long-term health burden.”

In 2019, more than 90% of the global population lived in areas where concentrations exceeded the 2005 WHO air quality guideline for long-term exposure to PM2.5. Countries with strong policy-driven improvements in air quality have often seen a marked reduction in air pollution, whereas declines over the past 30 years were less noticeable in regions with already good air quality, according to WHO.

The rapid scenario analysis by WHO shows that almost 80% of deaths related to PM2.5 could be avoided in the world if the current air pollution levels were reduced to those proposed in the updated guideline.

At the same time, the achievement of interim targets would result in reducing the burden of disease, of which the greatest benefit would be observed in countries with high concentrations of fine particulates (PM2.5) and large populations, the organization pointed.

Calls for action

Greenpeace International Air Pollution Scientist based at the University of Exeter in the UK, Dr. Aidan Farrow, said the WHO has strengthened its guidelines incorporating new advances in research, but these targets for clean air are meaningless if they aren’t addressed with government action.

“What matters most is whether governments implement impactful policies to reduce pollutant emissions, such as ending investments in coal, oil and gas and prioritizing the transition to clean energy. The failure to meet the outgoing WHO guidelines must not be repeated,” said Dr. Farrow.

Greenpeace India’s analysis of PM 2.5 data aggregated by IQAir found that air quality failed to meet the 2021 guidelines in all of the world’s 100 biggest cities during 2020. (79 exceeding the 2005 AQG, 92 exceeding the 2021 AQG)

In Delhi, city-wide annual average PM2.5 air pollution levels exceeded the 2005 WHO guideline by nearly eightfold in 2020, the highest margin of all cities in the dataset. The city’s air quality surpassed the stricter 2021 guideline by nearly seventeen-fold.

In Jakarta and Beijing, city-wide averages of annual mean PM2.5 recorded in 2020 by IQAir were approximately four times the 2005 guideline level. In Mexico City, Seoul and Bangkok, the averages of measured concentrations were double the 2005 WHO guideline level (Bangkok’s surpassed the 2021 guidelines by 4.2 fold).

Annual mean PM2.5 near-surface concentration in 2020 in the 100 most populous cities worldwide compiled and analysed by Greenpeace. In all cities with available data air quality exceeded the WHO’s 2021 AQG. Credit: Greenpeace

“It’s important to remember that there is no safe level of air pollution exposure. Long-term exposure to low-levels of air pollution can cause a gradual but serious deterioration of our health, resulting in diseases like lung cancer, stroke, diabetes, and, ultimately, in avoidable deaths. Air quality policies must prioritize health and strive for continuous air quality improvements in all places,” said Dr. Farrow.

Mr. Avinash Chanchal, an air pollution campaigner at Greenpeace India, said the world now has all the economically viable tools to solve the air pollution crisis. In most parts of the world, it is more cost-effective to develop renewable energy sources, such as wind and solar, than to keep burning coal, oil or gas, even before taking the economic burden of air pollution into account.

“At this point, addressing air pollution is a question of political will, not technology,” said Mr. Chanchal.