Air quality limits 'insufficient'
Air quality limits in Europe may not be sufficient to protect people from harmful sooty particles in traffic and factory fumes, research suggests.
Researchers estimated that for every five microgrammes per cubic metre increase in annual exposure to fine-particle pollution the risk of dying from natural causes rises by 7%.
"A difference of five microgrammes can be found between a location at a busy urban road and at a location not influenced by traffic," said lead scientist Dr Rob Beelen, from Utrecht University in the Netherlands.
"Our findings suggest that significant adverse health effects occur even at... concentrations well below the EU annual average air quality limit value of 25 microgrammes per cubic metre. The World Health Organisation (WHO) air quality guideline is 10 microgrammes per cubic metre and our findings support the idea that significant health benefits can be achieved by moving towards this target."
The scientists pooled data from 22 studies involving 367,251 people.
Annual average air pollution concentrations of nitrogen oxides and sooty pollutants called particulates were linked to home addresses to estimate exposures. Traffic density on the nearest road and total traffic load on all major roads within 100 metres of people's homes were also recorded.
Among the participants, 29,076 died from natural causes during an average follow-up period of 13.9 years.
The results, published in The Lancet medical journal, showed that long-term exposure to fine particles with a diameter of less than 2.5 micrometres, called PM2.5s, posed the greatest threat to health. This was the case within concentration ranges well below the limits set out in European legislation.
The association between prolonged exposure to PM2.5s and premature death remained significant even after adjusting for a wide range of factors such as smoking, socio-economic status, physical activity, education and body-mass index.
The researchers also noted a gender effect, with fine PM2.5 particles associated with excess mortality in men but not in women.
Professor Frank Kelly, an environmental health expert at King's College London, said: "This study enhances an increasing scientific evidence base that PM2.5 poses a danger to health at concentrations below current EU limit values and supports the ongoing WHO review of European air quality policies.
"Results such as these, plus recently published data claiming combustion emissions in the US account for 200,000 premature deaths per year, show that policy measures have enormous potential to create a cleaner and healthier environment.
"It's now important to effectively translate the scientific evidence into refined regulation and pollution control strategies in order to reduce the burden of disease attributable to ambient PM pollution. Such action is particularly urgent in cities where concentrations of pollutants routinely breach current EU limit values, let alone the more stringent and health-based WHO guidelines."