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Exposure to air pollution may hasten brain aging, a new study has found. 一项新研究发现，暴露在空气污染中可能会加速大脑衰老。 Researchers studied 1,403 women without dementia who were initially enrolled in a large health study from 1996 to 1998. They measured their brain volume with magnetic resonance imaging scans in 2005 and 2006, when the women were 71 to 89. 这项研究的对象为1403名未患痴呆症的女性，她们曾在1996年至1998年间参与过另一项大型健康研究。在2005年和2006年，研究人员用磁共振成像扫描的方式，测量了这些年纪在71岁至89岁之间的女性的脑容量。 Using residential histories and air pollution data, they estimated their exposure to air pollution from 1999 to 2006. They used data recorded at monitoring sites on exposure to PM 2.5 — tiny particulate matter that easily penetrates the lungs. 研究人员利用居住记录和空气污染数据，对她们从1999年到2006年暴露在空气污染中的情况进行了估算。他们使用了监测PM 2.5的站点记录的数据。PM 2.5是一种容易进入肺中的微粒物。 Each increase of 3.49 micrograms per cubic centimeter cumulative exposure to pollutants was associated with a 6.23 cubic centimeter decrease in white matter, the equivalent of one to two years of brain aging. The association remained after adjusting for many variables. | 
