Toxic air in global cities has forced the World Health Organization (WHO) to call on governments to step up their efforts to tackle pollution before the consequences become unmanageable.
According to the WHO’s head of public health, Maria Neira, air pollution has now become the global number one health problem, threatening not only the lives and health of city-dwellers, but also the economy.
"This is one of the biggest public health issues we have ever confronted," Neira said.
"It is an enormous cost not only in terms of mortality, but in terms of treating diseases and the costs of hospitalisation, as most of these diseases are chronic. It will also lead to less working days and a lower quality of life."
According to figures published last year, seven million people die around the world every year prematurely due to diseases caused by air pollution.
Neira’s remarks are based on data collected in 2,000 cities around the world, which indicates that people are frequently exposed to air pollution levels far exceeding levels considered safe by the WHO.
London for example, has already breached air pollution limits for the whole of 2016.
Exposure to air pollution has now been linked to cardiovascular disease, Neira said, as well a catalogue of other illnesses.
Neira urged global governments to do more to make cities more eco-friendly, building energy efficient houses and improving public transport systems, as well as committing to the use of renewable energy.
"There is also a role to be played on an individual level, like choosing not to take the car," she added.
"I think it is a societal decision, but it is important that, as well as the Government stepping in, citizens are also informed."
The warning comes ahead of next month's release of a new report detailing the amount of deaths caused by poor air quality.