如 果证明了这之间的联系，我们应该如何关注这件事？科学家强调对人的短期风险相对很小，当然不能当做造成肥胖的原因，而不考虑生活方式的其他方面。但是对生 活在污染严重城市的广大群体的长期影响是巨大的。布鲁克说每个人都受到某种程度的污染，这是几十亿人不由自主的受到连续污染，因此整体的影响就更大了。
Large studies from cities across the world suggest that humans might be suffering the same consequences. Chen, for instance, examined the medical records of 62,000 people in Ontario, Canada over a 14-year period. He found that the risk of developing diabetes rose by about 11% for every 10 micrograms of fine particles in a cubic metre of air – a troubling statistic, considering that the pollution in some Asian cities can reach at least 500 micrograms per cubic metre of air. Across the Atlantic, a Swiss study saw a similar signs of increased insulin resistance, hypertension, and waist-circumference in a sample of nearly 4,000 people living among dense pollution.
大 量来自全球的研究表明，人类可能会受到同样的影响。例如陈先生研究了14年间加拿大安大略省62000人的医学记录，发现每立方空气中的微小颗粒每增加 10毫克，患糖尿病的风险增加11%。考虑到在亚洲一些城市每立方空气中的污染物超过500毫克，这项统计令人担忧。瑞士在对生活在重污染区的4000人 的研究中发现了类似的结果，胰岛素抗性增加、高血压和腰围增加。
The study found that for every additional 10 micrograms over 20， the risk to people with type A， B， or AB blood increased by 25 per cent， but only by 10 per cent for people with type O。
If the link is proven, how concerned should we be? The scientists stress that the individual, short-term risk to any one person is relatively small, and certainly shouldn’t be used as an excuse for obesity by itself, without considering other aspects of your lifestyle. But given the sheer number of people living in cities with high pollution, over the long term the total number of casualties could be enormous. “Everyone is affected by pollution to some degree,” says Brook. “It’s continuous, involuntary exposure, across billions of people – so the overall impact becomes much greater.”
威尼斯手机娱乐官网 ，Traffic fumes and cigarette smoke are the chief concerns, with their tiny, irritating particles that trigger widespread inflammation and disrupt the body’s ability to burn energy. While the short-term effects are minimal, over a lifetime it could be enough to contribute to serious disease – besides the respiratory illnesses more commonly associated with smog. “We are starting to understand that the uptake and circulation of air pollution in the body can affect more than just the lungs,” says Hong Chen at the University of Toronto, Canada.
In contrast the risk rose only rose by 40 per cent for those with type O。
Around 55 per cent of people are A， B， or AB and they are thought to be at greater risk of heart problems because their blood contains greater quantities of a clotting agent。
Some puzzling studies appear to show that tiny airborne particles may contribute to obesity, diabetes and heart disease. Should we be concerned?
Air pollution in Britain is thought to contribute to around 40，000 early deaths a year， according to the Royal Colleges of Physicians and of Paediatrics and Child Health。
The scientists have been particularly concerned about the effects on young children, with some concern that a mother’s exposure to these pollutants may alter the baby’s metabolism so they are more prone to obesity. Consider the work of Andrew Rundle at Columbia University, who studied children growing up in the Bronx. During pregnancy, the children’s mothers had worn a small backpack that measured the air quality as they went about their daily business, and over the next seven years the children’s health was monitored at regular intervals. Controlling for other factors (such as wealth and diet), the children born in the most polluted areas were 2.3 times more likely to be considered obese, compared to those living in cleaner neighbourhoods.
“The association between heart attacks and pollution in patients with non-O blood isn‘t something to panic over， but it is something to be aware of，” said Dr Benjamin Horne， a clinical epidemiologist and lead investigator of the study from the Intermountain Medical Center Heart Institute in Salt Lake City。
Laboratory mice offered some of the earliest concrete clues that the effects of air pollution may penetrate far beyond the lungs. Their breeder at the Ohio State University, Qinghua Sun, had been interested in studying why city-dwellers seem to be at a particularly high risk of heart disease compared to country folk. Lifestyle, of course, could be one reason: in most major cities a fast food chain is rarely more than a block away, for instance, which might encourage unhealthy eating. Nevertheless, he wondered if another answer may be hanging, invisibly, in the air we breathe.
“In the information we provide to our patients about pollution， we try to stress that they can do something about it to reduce their risks： Stay indoors out of pollution。 Exercise indoors。”
虽 然这些发现令人头疼，阅读时还是要采取谨慎的态度。哈佛医学院的Abby Fleisch说，这些研究只展示了受到空气污染和结果之间的联系，并没有证明这些原因直接导致了结果。尽管如此，她自己的发现似乎也跟总体趋势一致，她 发现即使在前六个月中母亲生活在污染区的儿童体重也是增加的更快，但是她强调不能保证没有漏掉空气污染之外密切相关的其他因素。
The exact mechanism is still debated, but subsequent animal experiments suggest the air pollution triggers a cascade of reactions in the body. Small particles, less than 2.5 micrometres wide, are thought to be primarily to blame – the same minuscule motes of pollutant that give city air its gauzy haze. When we breathe in, the pollutants irritate the tiny, moist air sacs that normally allow the oxygen to pass into the blood stream. As a result, the lungs’ lining mounts a stress response, sending our nervous system into overdrive. This includes the release of hormones that reduce insulin’s potency and draws blood away from the insulin-sensitive muscle tissue, preventing the body from tightly controlling its blood sugar levels.
Despite these troubling findings, we should be cautious about reading too much into them. “They only draw a link between exposure and outcome, but can’t prove that one factor causes another,” says Abby Fleisch at Harvard Medical School. Even so, her own findings would seem to agree with the general trend – she has shown that even in the first six months, babies of mothers living in polluted areas appear to put on weight more rapidly than those in cleaner areas – but she stresses that we still can’t be sure we haven’t neglected some other factor, besides pollution, that could explain the apparent link.
Safe levels of air pollution are generally considered to be under 20 micrograms per cubic metre， but during levels of high pollution， the PM2.5 count - the measure of small particulates in the air - raise to around 60 micrograms per cubic metre。 In London it has been known to rise to 197。
A study of 14 years of patient data from the Intermountain Medical Center Heart Institute in Utah， US， found that the risk of a heart attack or chest pain doubled for people of type A， B， or AB blood when pollution hits high levels。
All of which knocks the body’s energy balance off-kilter, leading to a constellation of metabolic disorders, including diabetes and obesity, and cardiovascular problems such as hypertension.
To find out more, he started to raise laboratory mice in the kinds of conditions you might find across various cities. Some breathed filtered, clean, air, while others were funnelled the kinds of fumes you might find next to a motorway or busy city centre. Along the way, his team weighed the mice and performed various tests to study how their metabolism was functioning.
Recent research by the World Health Organisation found that 44 major UK towns and cities now breach WHO guidelines on air quality with particulate levels so high they cause six million sick days each year。
How strong is the evidence from these studies, and should you be concerned?