Surgical masks have become an increasingly common sight on the streets of some of the world's biggest cities.
With their steely eyes peering over light blue masks, people in China, India and Korea have become the 'face' of a 'terrifying' global threat, which if not addressed urgently could lead to 6 to 9 million premature deaths a year by 2060.
According to a report by the Organisation for Economic Cooperation and Development (OECD), air pollution around the world has reached dangerous new levels and the global GDP could take a massive hit as a consequence.
An economic cost of around $2.6 trillion annually would come as a result of healthcare bills, lost work days, and a reduction in crop yields, according to the OECD.
OECD environmental director Simon Upton said, "The number of lives cut short by air pollution is already terrible and the potential rise in the next few decades is terrifying.
"If this is not motivation enough to act, this report shows there will also be a heavy economic cost to not taking action."
— Catherine Bremer (@CatherineBremer) June 9, 2016
Outdoor air pollution caused more than 3 million premature deaths in 2010, but the annual number could triple by 2060.
According to a report in The Guardian, air pollution is now a major contributor to stroke, respiratory and heart problems.
The biggest rise in mortality rates from air pollution are forecast to be in India, China, Korea and central Asian countries such as Uzbekistan, where expanding populations and congested cities expose more people to power plant emissions and vehicle exhaust.
India had four of the 10 cities in the world with the worst air pollution, the World Health Organisation said last month.
Below is an infographic showing the most polluted megacities with over 14 million people:
— The Lancet (@TheLancet) June 10, 2016
The OECD says death rates due to air pollution are expected to stabilise in the United States and decline in much of Western Europe by 2060 partly due to a move towards cleaner energy and transport.
Leading sources of air pollution include vehicles, especially diesel-engined models, the heating and cooling of large buildings, waste management, agriculture and the use of coal and diesel in power generation.