Walking or cycling is good for you even in polluted cities, researchers have found.

研究人员发现，即使在有空气污染的城市，行走或骑车也是对健康有益的。

The health benefit of physical activity outweighs the harm caused by chemicals and dust puffed out by traffic and industry, according to Cambridge academics.

根据剑桥大学学者的研究，体育锻炼对健康的好处要大于汽车和工厂排放的化学物质和灰尘造成的危害。

Air pollution is a major problem in British cities, and is estimated to contribute to 40,000 early deaths in Britain every year.

空气污染是英国城市的主要问题，据估计，英国每年有四万人因空气污染而过早死亡。

People who exercise in polluted areas are thought to put themselves at increased risk, because they take deeper breaths, inhaling more of the toxic pollution and particles that do such damage.

人们通常认为，在污染区域进行体育锻炼会增加患病风险，因为锻炼时呼吸更深，会吸入更多有毒污染物和颗粒物，而这些污染物都对健康有害。

But a new study, published in the journal Preventive Medicine, suggests that the act of exercising outweighs this risk, because physical activity reduces the risk of diseases such as diabetes, heart disease, and several cancers.

但是，一项发表在《预防医学》期刊上的最新研究表明，锻炼带来的益处远甚于它带来的风险，因为体育活动可降低患糖尿病、心脏病和某些癌症的风险。

Experts at the Centre for Diet and Activity Research - a collaboration between the universities of Cambridge and East Anglia - used computer simulations to compare the risks and benefits of exercising in polluted areas around the world.

饮食与锻炼研究中心的专家使用电脑仿真技术，比较了在世界各地污染地区进行体育锻炼的风险和益处。饮食与锻炼研究中心由剑桥大学和东安格利亚大学合作建立。

Only 1 per cent of cities are so polluted that the risks start to overcome the benefits of physical activity after half an hour of cycling.

只有1%的城市不符合上面的结论——这1%的城市因为污染太严重，以至于骑行半个小时后，体育锻炼的风险就开始超过健康收益了。

Study leader Dr Marko Tainio, of the University of Cambridge, said: ‘Our model indicates that in London health benefits of active travel always outweigh the risk from pollution.

领导该研究项目的剑桥大学马可·泰尼奥博士说：“我们的模型显示，在伦敦，体育活动的健康收益总是大于污染的危害。

‘Even in Delhi, one of the most polluted cities in the world – with pollution levels ten times those in London – people would need to cycle over five hours per week before the pollution risks outweigh the health benefits.

“即便在世界上污染最严重的城市之一印度德里，污染水平是伦敦的十倍，人们每周仍然可以骑行五个多小时，健康收益大于风险。继续增加锻炼则会危害健康。

‘We should remember, though, that a small minority of workers in the most polluted cities, such as bike messengers, may be exposed to levels of air pollution high enough to cancel out the health benefits of physical activity.’

“然而我们也要记住，在污染最严重的城市里，有一小部分工人，比如骑自行车的邮差，可能长时间暴露在空气污染严重的环境中，就抵消了体育运动的益处。

Senior author Dr James Woodcock added: ‘Whilst this research demonstrates the benefits of physical activity in spite of air quality, it is not an argument for inaction in combating pollution.

该研究的资深作者詹姆斯·伍德科克补充说：“尽管这项研究证明，即使在空气质量差的情况下，进行体育运动也是有好处的，但并不意味着我们在对抗污染方面就可以不作为。

‘It provides further support for investment in infrastructure to get people out of their cars and onto their feet or their bikes – which can itself reduce pollution levels at the same time as supporting physical activity.’

“它进一步说明，我们要加大对基础设施的投入，鼓励人们从汽车上下来，靠双脚或自行车行进——这样既可以降低污染水平，也可以加强体育锻炼。”