Australia — THE SMOKE HAZE BLANKETING parts of New South Wales today could increase the incidence of cancer, with the World Health Organisation yesterday warning outdoor air pollution is a leading cause of cancer in humans.
“The air we breathe has become polluted with a mixture of cancer-causing substances,” said Kurt Straif of the WHO’s International Agency for Research on Cancer (IARC).
“We now know that outdoor air pollution is not only a major risk to health in general, but also a leading environmental cause of cancer deaths.”
Dr Martine Dennekamp research fellow at the Department of Epidemiology and Preventive Medicine at Monash University warned of the dangers of bushfire smoke.
“The air pollutant that seems most important in relation to population health effects of bushfire smoke is particulate matter, and in particular the very small particles that can penetrate deep into the lungs,” she said.
“As with urban air pollution, those with pre-existing heart or lung disease, young children and the elderly are more likely to be affected by the smoke. During bushfire smoke episodes, particulate matter concentrations are usually much higher than urban background concentrations, at which effects on respiratory health have been observed.”
New South Wales’ air quality index over the last day has reached ‘hazardous’ levels in some places. Bargo, inland of Wollongong, was strongly affected, with particulate matter measuring an average of 418 on Thursday, more than twice the benchmark for being labelled ‘harzardous’.
IARC director Christopher Wild said outdoor air pollution of all kinds, including particulates, has been classified as a ‘Group 1’ cause of cancer, the riskiest category on its four-step scale.
The IARC underlined that a panel of top experts had found “sufficient evidence” that exposure to outdoor air pollution caused lung cancer and raised the risk of bladder cancer. But Wild underlined that air pollution was not a primary cause of the disease.
“We have well over a million lung cancer cases per year, the vast majority of which are actually due to tobacco, rather than I think around 10 per cent, perhaps, which are to things like ambient air pollution,” he said.
In the past, the IARC had measured the presence of individual chemicals and mixtures of chemicals in the air including diesel engine exhaust, solvents, metals, and dust. Diesel exhaust has already been classified as carcinogenic by the IARC. Air pollution is already known to increase the risk of respiratory and heart diseases.
The latest findings were based on overall air quality, and based on an in-depth study of thousands of medical research projects conducted around the world over decades.
The most recent data, from 2010, showed that 223,000 lung cancer deaths worldwide were the result of air pollution, the agency said.
The predominant sources of outdoor air pollution were not occasional bushfires, but the constant contributions of transport, power generation, emissions from factories and farms, and residential heating and cooking.
“Our task was to evaluate the air everyone breathes rather than focus on specific air pollutants,” said the IARC’s Dana Loomis.
“The results from the reviewed studies point in the same direction: the risk of developing lung cancer is significantly increased in people exposed to air pollution,” he added.
“Nobody has private air. We can’t do very much for the air we breathe. This really needs collective action to solve the problem,” he said.
Wild said he hope the report will spur the international community into action to clean up pollution.
“Classifying outdoor air pollution as carcinogenic to humans is an important step,” said Wild.
“There are effective ways to reduce air pollution and, given the scale of the exposure affecting people worldwide, this report should send a strong signal to the international community to take action without further delay.”