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(单词翻译:双击或拖选)
Air Pollution Linked to Cognitive1 Decline
Several years ago a massive survey of women called the Nurses' Health Study began collecting data on memory, thinking skills and other cognitive measures.
Jennifer Weuve of the Rush Institute of Healthy Aging in Chicago combined that data with information about air quality where the women lived.
In particular, she compared the level of particulate2 matter in the air with the change in cognitive scores over several years.
"The most important finding of our study is that women who were exposed to higher levels of ambient particulate matter over the long term experienced more decline in their cognitive scores over the four-year period that we followed them up."
If cognitive decline was more rapid where air quality was worse, how could the pollution be causing the loss of mental skills and function?
Weuve says the tiny particulates3 in the air might be getting into the brain directly. They're so small - 10 microns, one-thousandth of a millimeter - that they can evade4 the body's usual defenses and may be able to reach the brain either via the lungs or through the sinus passages in the head.
"Several studies have found that these particles - at least some of them - can actually get into the brain where they can cause inflammation and might even trigger some of those microscopic5 changes that are typical of Alzheimer's Disease."
Or it may be a more indirect effect. Numerous studies have identified an association between air pollution and cardiovascular disease, and the cognitive decline may be a result of damage to the blood supply.
For example, research published in the same journal as Weuve's paper, the Archives of Internal Medicine, found a higher risk of stroke on days when there were more particulates in the air. The fine particles were mainly from vehicle exhausts.
And a new study in the journal of the American Medical Association, JAMA, combined results of 34 studies and found a statistically6 significant association between heart attack risk and a wide range of air pollutants7, excepting ozone8.
The researchers say that as a risk factor for heart attack, air pollution isn't as dangerous as things like smoking and high blood pressure, but on the other hand, air pollution, especially for those in urban areas and industrialized countries, is an unavoidable part of daily life.
1 cognitive | |
adj.认知的,认识的,有感知的 | |
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2 particulate | |
adj.微小的;n.微粒,粒子 | |
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3 particulates | |
n.微粒,粒子( particulate的名词复数 ) | |
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4 evade | |
vt.逃避,回避;避开,躲避 | |
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5 microscopic | |
adj.微小的,细微的,极小的,显微的 | |
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6 statistically | |
ad.根据统计数据来看,从统计学的观点来看 | |
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7 pollutants | |
污染物质(尤指工业废物)( pollutant的名词复数 ) | |
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8 ozone | |
n.臭氧,新鲜空气 | |
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