New research suggests the silent killer of air pollution has become an insidious ' pandemic', even more dangerous and deadly than war, violence and many diseases.

Using World Health Organisation (WHO) data, researchers have previously linked air pollution to an extra 8.8 million premature deaths in 2015. Across all persons worldwide, an updated analysis now shows that huge loss resulted in a shorter global life expectancy, shaving off an average of nearly three years.

"Since the impact of air pollution on public health overall is much larger than expected, and is a worldwide phenomenon, we believe our results show there is an 'air pollution pandemic'," says atmospheric chemist Thomas Münzel of the Max Planck Institute.

Of course, not all humans are impacted equally by air pollution. When dangerous particles and gases are hanging around in the atmosphere, young and old people are generally more susceptible, as are those who live in regions with high emissions.

Globally, the authors say, about 75 percent of deaths attributed to air pollution occurred in people over 60 years old. And among the young, most deaths were for kids under five.

Still, even when it comes to humanity at large, public health experts warn air pollution is an outstanding and overlooked risk.

In 2015, all the violence in the world could not come close to the impacts of air pollution (these deaths only shortened global life expectancy by 0.3 years). Even tobacco smoking decreased life expectancy by roughly a third less. And, unlike cigarettes, ambient air can't exactly be avoided. 

"It is remarkable that both the number of deaths and the loss in life expectancy from air pollution rival the effect of tobacco smoking and are much higher than other causes of death," says physicist Jos Lelieveld from the Cyprus Institute in Nicosia.

"Air pollution exceeds malaria as a global cause of premature death by a factor of 19; it exceeds violence by a factor of 16, HIV/ AIDS by a factor of 9, alcohol by a factor of 45, and drug abuse by a factor of 60."

In their model, the researchers examined the effect of air pollution on six categories of disease, including respiratory infections, pulmonary disease, lung cancer, as well as high blood pressure and diabetes.

In the end, it was the cardiovascular diseases that were deemed the leading cause of premature death from air pollution, responsible for roughly 43 percent of the total loss in life expectancy.

"Air pollution causes damage to the blood vessels through increased oxidative stress, which then leads to increases in blood pressure, diabetes, stroke, heart attacks and heart failure," explains Lelieveld.

Compared to other causes of premature death, the authors say air pollution looks particularly dangerous. And while it's true not all pollution in the air is caused by humans, the authors found a whopping two thirds of it was. Of all the deaths caused by air pollution in 2015, this means roughly 25 to 80 percent could have been avoided were it not for these anthropogenic pollutants.

If all human-made emissions were suddenly stopped, they predict average life expectancy would increase by just over a year worldwide: That's more than 5.5 million early deaths that could be avoided each year. 

Unfortunately, in many parts of the world, the opposite trend is at play.

In 2017 and 2018, for instance, data revealed air pollution worsened in the United States after years of sustained improvement. In 2018 alone, low air quality was linked to nearly 10,000 additional deaths compared to 2016.

Last year, a shocking WHO report revealed 93 percent of all children in the world under the age of 15 are breathing toxic, polluted air.

For many, the consequences are inescapable. According to the new model, East Asia experienced the highest loss of life expectancy from avoidable air pollution in 2015 and the vast majority of that loss could have been avoided with reduced emissions.

In North America, the average loss of life expectancy was 1.4 years, and just over a year of that could be prevented, the authors say, mostly by phasing out fossil fuels.

Other places had less room for progress. In Africa, where dust is a major air pollutant, emission reductions could only make up for 0.7 years of lost life expectancy.

"Policy-makers and the medical community should be paying much more attention to this," says Münzel.

"Both air pollution and smoking are preventable, but over the past decades much less attention has been paid to air pollution than to smoking, especially among cardiologists."

In light of their findings, the authors ask public health officials and physicians to update their guidelines and include chronic air pollution as an important risk factor for heart disease, right along with smoking, diabetes and high blood pressure.

The study was published in Cardiovascular Research.