The World Health Organization(世界卫生组织) says air pollution kills seven million people around the world each year. Even if polluted air does not kill us, it can make us very sick.
However, breathing dirty air may do more than hurt your body. It can also affect(影响) your brain and your ability to think.
A new study shows that air pollution can cause a "huge" reduction(减少)in our intelligence(智商).The researchers reported that long-term exposure(暴露) to air pollution can affect a person's mental(智力的) abilities in two areas: language and math.
Xi Chen, the researcher of the Yale School of Public Health led the study. He and his team found that breathing polluted air can reduce a person's education level by about one year.
Chen said that the effect(结果) generally is worse for those over 64 years of age, for men and for those with little or no education.
"The older persons-they are more affected. And we find, quite interestingly, men are more affected than women. And people working outdoors are more affected than people working indoors.
The researchers noted that the effect of pollution on language ability is even more serious as people age, especially among men and the less educated.
Why were language skills more affected than math? There are two main kinds of tissue(组织)in the brain: white matter and grey matter. White matter is more connected with a person's language skills, while grey matter is connected to our ability to solve math problems. Studies have shown that air pollution has a great effect on the white matter in the brain, but not the grey matter.
Chen said that air pollution did affect the math skills, just not as much as their language skills.
