Small increases in air pollution that are well below current safety limits can raise the risk of lung cancer and heart attacks, according to two new studies.

© Getty Images
Exhaust fumes from a car in London
Researchers found that long term exposure to microscopic particles of soot at levels similar to those found in suburban areas of Britain can increase the risk of lung cancer by up to 36 per cent.

The short term impact of the same levels of these sooty particles, which are produced by diesel exhausts, also increased the risk of being admitted to hospital or dying from heart failure by two per cent.

The particles, which are more than 100 times small than a human hair, can become lodged in the lungs and pass through into the blood stream, causing inflammation.

The scientists behind the two studies say that their findings indicate that current safety limits on air pollution are still too high and need to be lowered.

"Everybody is exposed to air pollution and it is difficult to escape," said Dr Anoop Shah. "Our results indicate that the lower the levels, the better it is.

"The pollution effects can be chronic which can produce the sort of conditions like lung cancer, but acute exposures on a day-to-day basis can also affect the way your heart pumps blood."

In the EU, the safety limit for tiny pollution particles known as PM2.5s, is 25 micrograms in every cubic metre of air. For larger particles, called PM10s, it is 40 micrograms per cubic metre.

The annual average in the UK is around 10-15 micrograms per cubic metre for PM2.5s and 19-22 micrograms per cubic metre for PM10s, but areas around busy roads can often exceed this.

However, in a major analysis of more than 313,000 people in 17 European countries, a paper published in the journal Lancet Oncology, shows that even at these levels there is a higher risk of lung cancer.

The researchers, who modelled air pollution levels at people's home addresses and compared it to cancer diagnosis rates, found that for every five microgram increase of PM2.5s in a cubic metre of air, the risk of developing lung cancer over a 13 year period increased by 18 per cent.

For every 10 micrograms increase in PM10s per cubic metre of air, the risk of lung cancer increased by 22 per cent.

The UK's official air pollution watchdog estimates that around 29,000 people die as a result of air pollution each year, but that figure may now need to be revised following the new research.

Each year, roughly 40,000 people are diagnosed with lung cancer in the UK and it is the most common form of death from cancer in the country.

Dr Takashi Yorifuji, who led the study from Okayama University Graduate School of Environmental and Life Science, said: "At this stage, we might have to add air pollution, even at current concentrations, to the list of causes of lung cancer and recognise that air pollution has large effects on public health."

A second paper published in the Lancet also examined the impact of short term pollution changes on heart health.

It found fluctuations in pollution that can typically occur over the course of a couple of days in Britain's towns and cities, could increase the risk of being taken to hospital or dying of heart failure.

It is thought that car fumes and particles of pollution can cause blood vessels to become inflamed and reduce the efficiency of the heart, increasing the risk of a heart attack.

The scientists, based at the University of Edinburgh and supported by the British Heart Foundation, reviewed 35 studies into the health affects of daily changes in air pollution.

They found that the risk of being admitted to hospital or dying from heart failure rose by two per cent for 10 micrograms of PM10s and PM2.5s per cubic meter.

A small increase in sulphur dioxide, which is also emitted by cars and heavy industry, could increase the risk by 2.36 per cent.

The authors claim that reducing pollution even by a modest amount could help save thousands of lives every years.

Dr Shah, the lead author on the study, added that visiting countries where pollution is higher could also present an additional risk to heart patients.

He said: "On a week-to-week basis we are seeing changes in air pollution that can impact on the number of patients that die or end up in hospital with heart failure.

"We were looking at developed countries, but the risk would be higher in developing countries where there is more pollution.

"This could pose a travel risk to some people that is worth thinking about."

Although there has been progress in reducing air pollution over the past decade in the UK, experts said both papers made a strong case for increased efforts to cut it further.

Prof Jon Ayres, an expert in respiratory medicine at the University of Birmingham, said: "There is now no doubt that fine particles are a cause of lung cancer.

"Air pollution contributes to heart disease both through long and short term exposure and there is no doubt that reducing air pollution will reduce the burden from heart disease."