More than 3 million people die prematurely each year from outdoor pollution and without action deaths will double by 2050. The work did not include the effect of indoor air pollution, from cooking fires for example, which is estimated to cause an additional 3.4 million deaths a year.
Wood and coal burning for heating homes and cooking is the biggest cause, especially in Asia, but the research reveals a remarkably heavy toll from farming emissions in Europe and the US, where it is the leading cause of deaths. The report warns that, unless action is taken, the number of deaths – already equivalent to six deaths every minute – will double by 2050.
“This projection should sound alarm bells for public health agencies around the world,” said environmental health expert Professor Michael Jerrett, at the University of California.
Most air pollution deaths are caused by tiny particles that can be inhaled deep into the lungs. These cause heart attacks and strokes, which account for three-quarters of the 3.3 million annual deaths, with lung cancer and respiratory diseases responsible for the rest.
A third of all premature deaths were the result of using smoky fuels such as wood and coal for heating homes or cooking and using dirty diesel generators for electricity, all well-known hazards. This domestic energy use causes half the 645,000 annual deaths in India and a third of the 1.4 million annual deaths in China.
But the research found that agricultural emissions of ammonia had a “remarkable” impact, according to Professor Jos Lelieveld, at the Max Planck Institute for Chemistry in Germany, who led the research. A fifth of all global deaths resulted from these emissions, which come mainly from cattle, chickens and pigs and from the over-use of fertiliser. The ammonia reacts with fumes from traffic and industry to produce tiny particles and is the largest cause of air pollution deaths in the eastern US, Japan and in Europe. “For London, agriculture is the main source,” said Lelieveld. Across the UK, 48% of the premature deaths were ultimately the result of agricultural pollution.
Traffic pollution was still important in developed countries, causing a fifth of deaths, despite crackdowns on dirty vehicles. It only caused 5% of deaths across the globe as a whole, but this is likely to rise as more cars take to the road in developing countries. Air pollution from power stations, mainly coal-burning plants, was significant globally, causing one in seven deaths. It is the biggest single factor in the US, causing a third of the 55,000 annual deaths, compared to 16% in the UK. Natural air pollution, mostly dust in arid regions, caused almost a fifth of global air pollution deaths.
Dr Oliver Wild, an atmospheric scientist at Lancaster University in the UK said: “The study really brings home the need for air quality controls to avoid these additional deaths, particularly in heavily populated parts of Asia.”