Fresh air polluted by exhaust fumes and industrial emissions causes lung cancer, a team of World Health Organisation experts has officially declared.
Outdoor air pollution was officially classified as carcinogenic to humans by the cancer arm of the WHO after a review of the latest scientific evidence from around the world.
The International Agency for Research on Cancer (IARC) also highlighted an apparent link between air pollution and an increased risk of bladder cancer, although the findings were less conclusive.
Levels of pollution vary widely between urban and rural areas, but the working group said their findings applied to all regions of the world, and sent a “strong signal” to governments to tackle the problem immediately.
Dr Kurt Straif, head of the IARC Monographs Section which identifies environmental causes of cancer, said: “The air we breathe has become polluted with a mixture of cancer-causing substances.
“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.”
The latest available data suggest that in 2010, air pollution was responsible for the deaths of 223,000 lung cancer patients around the world.
Scientists from the IARC studied more than 1,000 academic papers on polluted air and, separately, small particles found in polluted air.
They found that the risk of developing lung cancer rises in tandem with increasing levels of either, concluding for the first time that outdoor air pollution is a cause of cancer.
Prof David Phillips of King’s College London, a member of the working group, said there was no particular threshold at which pollution becomes dangerous. “The higher the pollution, the greater the cancer risk,” he explained. “It does not suddenly kick in at a particular level.”
The programme had previously classed a variety of individual chemicals and mixtures found in polluted air as carcinogens, such as diesel engine exhaust, solvents, metals, and dusts.
Dr Dana Loomis, deputy head of the IARC monographs section, explained: “Our task was to evaluate the air everyone breathes rather than focus on specific air pollutants.
“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.”
Although the findings do not come as a surprise, they are likely to significantly increase the pressure on governments around the world to tackle pollution, which has risen rapidly around the world during industrialisation and was already known to raise the risk of conditions like heart and respiratory diseases.
Traffic, power stations, industrial and agricultural emissions, and cooking and heating in the home are the main causes of air pollution.
Dr Christopher Wild, director of the IARC, said: “Classifying outdoor air pollution as carcinogenic to humans is an important step. 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.”
据英国《每日电讯报》报道，世界卫生组织的专家们正式宣布，被汽车尾气和工业废气污染的空气会导致肺癌。
世界卫生组织回顾了来自世界各地的最新证据后，正式将户外空气污染定为致癌物质。
国际癌症研究机构也强调了空气污染和膀胱癌发病率增加的明显关联，虽然还未被确定。
都市和乡村的污染程度有很大的不同，但是研究组人员称他们的结果是来自全球所有区域的，并且极力要求各个政府尽快解决这个问题。
库尔特•斯特莱夫博士是国际癌症研究机构专论部的领导者，这个部门专门识别导致癌症的环境因素。他说：“我们呼吸的空气已被一种混合的致癌物质所污染。”
“现在我们知道户外空气污染不但是对健康不利的主要因素，而且是癌症死亡的主要环境因素。”
最新的数据表明，在2010年，空气污染造成全世界22.3万人死于肺癌。
国际癌症研究机构的科学家们研究了1000多份空气污染的学术报告，分别在被污染的空气中找到了小颗粒物。
他们发现患肺癌的风险与空气污染的增加是有关的，首次证明户外空气污染是癌症的诱因。
伦敦国王学院的戴维•菲利普斯教授是工作组的成员之一。他说没有特定的临界值可以判定污染到达什么水平才算危险。“污染指数越高，患癌症的风险越大，”他解释说。“它不会突然达到一个特定的水平。”
该计划曾将一些单独的化学物质和受污染空气中的混合物归类于致癌物质，如柴油机排气，溶剂，金属和灰尘。
国际癌症研究机构专论部副主任达纳•卢米斯博士解释说：“我们的任务是评估每个人呼吸的空气而不是关注特定的空气污染物。”
“从相同方向研究的结果表明：患肺癌的风险对于暴露于空气污染中的人们来说正显著增加。”
虽然研究结果并不让人感到惊讶，但他们可能会对世界各国政府在解决污染的问题上施加压力。这些污染在全球工业化期间迅速飙升，人们也已知它们会提高患心脏病和呼吸疾病的风险。
交通、电力站、工业和农业的排污，家庭做饭和供暖是空气污染的主要原因。
克里斯托弗•怀尔德博士是IARC的主任，他说：“将室外空气污染归类为致癌物对人类来说是一个重要的步骤。我们有许多有效的方法来减少空气污染。考虑到空气污染范围影响着全球人民，这个报告应该向国际社会发出强烈信号，让他们立即采取行动。”