The World Health Organisation (WHO) on Wednesday, 22 September, released the revised Air Quality Guidelines (AQG), which aims to reduce levels of air pollutants and decrease the burden of disease that results from exposure to air pollution worldwide.
Air pollution is one of the biggest environmental threats to human health, along with climate change.
There is increasing evidence that shows that even low-level exposure to air pollution is harmful to humans, especially with chronic exposure.
It disproportionately affects vulnerable populations – 91 percent of deaths from ambient air pollution occur in low-income and middle-income countries.
WHO estimates that air pollution causes around 7 million premature deaths every year.
Another study by Harvard University revealed that air pollution from fossil fuels is responsible for 1 in 5 deaths worldwide.
Children are also especially vulnerable, as exposure to air pollution in early childhood can lead to reduced lung capacity.
The new guidelines provide evidence of the damage air pollution has on human health and our understanding of the threats.
What Is Air Pollution & Where Are These Pollutants Found?
Air pollution is the contamination of the air we breathe, indoors or outdoors, by any chemical, physical or biological agent that is potentially threatening to human and ecosystem health.
The pollutants with the most robust evidence for public health concern include particulate matter (PM), ozone (O₃), nitrogen dioxide (NO₂) and sulfur dioxide (SO₂) and carbon monoxide (CO).
Air pollution originates from numerous sources of emission. Some of them are:
Domestic cooking and heating
Waste dump sites
What Are the New Guidelines?
Since the last 2005 global update, there has been a marked increase in the quality and quantity of evidence that shows how air pollution affects different aspects of health.
Several of the updated AQG values are now lower than 15 years ago. There are also now clearer insights about sources of emissions and the contribution of air pollutants to the global burden of disease, WHO said.
The guidelines recommend new air quality levels to protect the health of populations, by reducing levels of key air pollutants, some of which also contribute to climate change.
Compared to previous WHO guidelines, the new AQGs use new methods for evidence synthesis and guideline development, reinforce evidence on health effects, offer additional AQG levels among other things.
Pollution Burden Across the World
Over 90 percent of the world’s population live in areas that exceed the thresholds and limits for key air pollutants set by the WHO.
In 2020, at least 79 of the world’s 100 most populous cities had annual mean PM2.5 air pollution levels that breached the 2005 WHO Air Quality Guidelines, according to data published by IQAir.
In 8 of the 100 most populous cities worldwide no PM2.5 air pollution data is available, underlining the need for installment of ground sensors.
The pollution levels are consistently high in South Asia and the health burden is stark.
India’s Burden of Air Pollution
India last revised its air pollution standards in 2009, which have been more relaxed in comparison to WHO's prescribed guidelines and other Asian countries.
According to an analysis by Greenpeace India, among 100 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.
Meanwhile, Mumbai's exceeded 8-fold, Kolkata 9.4, Chennai 5.4, Hyderabad 7-fold and Ahmedabad exceeded 9.8 fold.
Calculating premature deaths and financial losses due to air pollution for 10 cities across the world, Delhi accounted for the maximum number of deaths, 57,000 in 2020 and 14 percent of GDP loss due to air pollution.
While GDP percentage share was highest amongst cities, the cost per capita was low in comparison to other cities which have higher per capita income and accumulated losses.
The Cost of Air Pollution
Air pollution increases the likelihood of premature death and many medical conditions including:
low birth weight
This is the case even in places where air pollution levels meet the 2005 WHO Air Quality Guidelines.
The health impact also takes a financial toll. Work absences due to sickness and lost life years due to premature death are accompanied by a substantial financial cost to society of up to 14 percent of total GDP in some locations.
The Way Ahead
The WHO’s updated Air Quality Guidelines are a firm warning about the severity of our air pollution crisis.
The goal of the guideline is for all countries to achieve recommended air quality levels.
Almost 80 percent 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, WHO says.
Here are some recommendations to address the crisis, according to Greenpeace:
Encourage governments to adopt WHO Air Quality Guidelines.
Encourage governments to urgently seek alternatives to burning fossil fuels for power, transport and industry.
Encourage governments to prioritise provision of transport infrastructure that revolves around walking and cycling – or for longer distances and people with additional needs, electric buses, trams and trains – and stop using fossil fuelled modes of transport.
Establish private vehicle-free days or zones in urban areas.
Create green spaces in urban areas and encourage biodiversity by planting trees.
Communicate with local residents: describe the health and financial problems of air pollution in their region and present solutions.