Two studies show effects on health of long- and short-term exposure to pollutants from traffic and industry
Sarah Boseley The Guardian 10 Jul 13;
Air pollution, chiefly from traffic exhaust fumes in cities, is having a serious and sometimes fatal effect on health, according to two studies that link it to lung cancer and heart failure.
Air pollution increases the risk of lung cancer even at levels lower than those recommended by the European Union, which are also standard in the UK, says a paper in the Lancet Oncology journal. Although smoking is a far bigger cause of lung cancer, a significant number of people will get the disease because of where they live.
The study, codenamed Escape, combined data from 17 cohort studies in nine European countries covering a total of almost 313,000 people. The size of the research gives it greater authority than previous work.
It looked at the effect of long-term exposure to nitrogen oxides and particulate matter – PM2.5, which has a diameter of less than 2.5 micrometres, and PM10, with a diameter less than 10 micrometres. Among the participants, 2,095 developed lung cancer during an average 13 years of follow-up.
The researchers, led by Ole Raaschou-Nielsen from the Danish Cancer Society Research Centre, found that for every increase of five micrograms per cubic metre of PM2.5 pollution, the risk of lung cancer rose by 18%, and for every increase of 10 micrograms per cubic metre in PM10 pollution the risk increased by 22%. They found no link between lung cancer and nitrogen oxides.
Air pollution comes from traffic – mostly diesel fumes – household heating and industry. In cities where people live close together, "there is no reason to believe this [risk] is restricted to people of higher or lower socio-economic status," said Raaschou-Nielsen. They found a link with lung cancer even at low levels of air pollution, so the message was, he said, "the less the better and the more the worse".
The second study, published by the Lancet, shows that short-term exposure to air pollution increases the risk of being admitted to hospital with and dying of heart failure.
There are 750,000 people living with the effects of heart failure in the UK, and 20 million worldwide. The study, led by Nicholas Mills from Edinburgh University and funded by the British Heart Foundation, shows that air pollution can have potentially fatal effects on them.
"Heart failure is a common, costly and fatal condition … and is one of the most frequent reasons for hospital admission," Mills said. "While the role of air pollution is well recognised as a risk factor for heart attacks, it has been less clear whether exposure increases the risk of adverse events in patients with other cardiovascular conditions like heart failure.
"Since the entire population is exposed to air pollution, even modest reductions in air pollution could have major cardiovascular health benefits and substantial healthcare cost savings."
The project combined data from 35 studies across the world on carbon monoxide, sulphur dioxide, nitrogen dioxide, ozone and particulate matter (PM2.5 and PM10). There was a strong link between hospitalisation or death from heart failure and all the pollutants except for ozone. The effect was strongest on the day of admission, suggesting high air pollution levels could trigger a heart failure crisis.
Governments have acted to curb air pollution, but Mills said the study showed the problems were still real. "Most of the studies have been from the last 10 years, well after most of the major legislation to reduce air pollution. This relationship is still present, even at levels in some countries which are very low," he said.
There is concern about pollution in the developing world, where data was not comprehensive enough to carry out studies, Mills said. Air pollution in some cities in China and India may be 10 or 20 times higher than in the UK. Nobody yet knows whether the health impact will be of the same increased magnitude.
