Exposure to even the lowest amounts of pollution raises the risk of an early death, scientists have said following major research.
In the world’s largest ever study of toxic air, researchers analysed levels of pollution in 652 cities across 24 countries and regions.
Scientists found when levels of pollution spike, so does the number of deaths, including those from heart failure, asthma and lung diseases.
More than 25million people died from cardiovascular or respiratory diseases over the 30-year study period, including 1.2million in the UK and 14.4million in the US.
Tiny particles, called particulate matter (PM) can be inhaled deep into the lungs where they irritate the lining and enter the bloodstream.
There is no ‘safe’ level of exposure, scientists said, suggesting current air quality guidelines don’t protect public health.
It comes after three damning scientific papers published yesterday warned pollution also raises the risk of depression, bipolar disorder and blindness.
Exposure to even the lowest amounts of pollution raises the risk of an early death, scientists have said following major research
Professor Yuming Guo, a co-author of the study from Monash University in Australia, said: ‘There’s no threshold for the association between particulate matter (PM) and mortality.
‘Even low levels of air pollution can increase the risk of death.’
The study, published in the New England Journal of Medicine, looked two types of PM – PM2.5 and PM10.
World Health Organization (WHO) guidelines state the average annual level for these pollutants should be 10 and 20 micrograms per cubic metre respectively.
However, the average annual level of PM2.5 over all cities studied was 35.6 micrograms per cubic meter, and 56 micrograms for PM10.
Researchers led by Dr Haidong Kan, from Fudan University in China, compared the death rate at periods when pollution levels were relatively low and when they were relatively high.
When there was a spike in levels of PM, there was also an increase in deaths.
For every increase of 10 micrograms per cubic meter in concentration of PM2.5, there was a 0.68 per cent increase of death per day.
An increase of 10 micrograms per cubic meter in concentration of PM10 led to an increase of 0.44 per cent in death per day.
Commenting on the study, Chris Griffiths, professor of primary care at Queen Mary University of London, said: ‘This study shows that in 652 cities across six continents the higher the pollution levels, the faster people are dying.
‘These are avoidable deaths. The authors provide the strongest evidence yet that target air pollution levels are set too high.’
If the increase of PM10 was applied to the UK, the number of deaths would go up by roughly seven a day, or just under 2,700 a year, according to Kevin McConway, emeritus professor of applied statistics, The Open University.
However, the effect of air PM levels on mortality rate did vary quite significantly from city to city.
Professor McConway said: ‘The figure they actually produced for the UK was an increase of only 0.06 per cent. That would correspond to only about one extra death a day in addition to the existing 1,633 deaths.
‘In other words, their UK figure is consistent with there being no short-term effect of PM10 levels on mortality at all.
‘The UK figure is the second lowest across all the countries from which they had data.
‘But the change is certainly measurable globally and, bearing in mind that everyone in a city is exposed to air pollution, this is yet more indication that air pollution really is a serious public health problem across the world.’
The findings show cardiovascular deaths, such as stroke and heart failure, and respiratory deaths, such as asthma and lung disease, also spiked when air pollution levels did.
For every increase of 10 micrograms per cubic meter in pollution, cardiovascular deaths rose by 0.47 per cent (PM2.5) and 0.36 per cent (PM10).
For respiratory deaths, the same increases in pollution level was linked to an increase of 0.74 per cent (PM2.5) and 0.47 per cent (PM10).
The authors wrote: ‘We found that the associations of mortality with PM concentrations were slightly stronger with PM2.5 than with PM10 in most countries.’
PM2.5, which is mainly produced by traffic fumes, industry and household heating, are tiny particles finer than a human hair.
Associate Professor Yuming Guo, from Monash University’s School of Public Health and Preventive Medicine in Australia, who was involved in the research, said the size of these particles are what makes them so dangerous.
He said: ‘The smaller the airborne particles, the more easily they can penetrate deep into the lungs and absorb more toxic components causing death.’
The study is the largest in terms of spanning countries across the globe. But it adds to well-established evidence that already exists.
It suggests that the levels of PM set by air quality guidelines, including from the WHO and UK law, is not stringent enough to protect public health.
Professor Jeremy Pearson, assistant medical director at The British Heart Foundation, said: ‘This latest research has confirmed previous findings from smaller studies that show a significant exposure to dangerous particulate matter over one to two days correlates to a small, but detectable, increase in deaths – the majority of which are due to cardiovascular events.
‘Air pollution is a public health emergency and is responsible for up to 11,000 heart and circulatory deaths every year in the UK alone.
‘Currently, the UK subscribes to EU guidelines on air pollution, which are far less strict than those set out by the World Health Organisation.
‘We urgently need to see the Government protect the nation’s health by setting out a clear and robust plan to adopt these strict guidelines by 2030.’
There was no evidence of a threshold in the findings, meaning there is no level of air pollution that isn’t dangerous.
For example, even Australians were similarly as vulnerable as other countries’ residents, despite them breathing smaller concentrations of pollution.
At the top of the table, Australia’s mortality rate increased by 1.42 per cent daily when levels of PM2.5 increased by 10 micrograms per cubic metre.
Professor Guo said: ‘The study found Australians are more sensitive to particulate matter air pollution and cannot effectively resist its adverse impacts.’
