American researchers say they have found the strongest link yet between ozone pollution and damage to health. Their findings show that short-term increases in ozone lead to higher death rates in cities.

Ozone is a form of oxygen. The gas is produced naturally in the upper atmosphere to protect the Earth against radiation from the sun. But human activity can also create ozone in the lower atmosphere. Gasses from vehicles and industry react with sunlight to form this ozone. Levels usually increase in the warmer months. Ozone is the main chemical in smog, the air pollution that is a combination of fog and smoke.

Ozone has been linked to heart and lung problems especially, and to higher rates of hospital cases. Researchers from Yale University and Johns Hopkins University did the study. Michelle Bell of Yale was the lead researcher. The Journal of the American Medical Association published the results. The researchers collected information on 95 American cities. These contain about 40% of the national population. The study compared deaths rates to ozone levels between 1987 and 2000. The research suggests that even a small increase in ozone, ten parts per thousand million, can lead to higher death rates the following week. The study found that the average daily number of deaths rose point-five percent. Heart and lung related deaths rose point-six percent. And deaths among older people rose point-seven percent.

The study is one of the largest ever done of ozone and death rates. The researchers note that ozone is widespread in the United States and many other countries. The United States Environmental Protection Agency is re-examining its air pollution rules. The current limit for ozone is eighty parts per thousand million for an eight-hour period. Limits were higher in the past. But the researchers say they found an increase in deaths even below the current levels.

Whether rich or poor, parents who have books in the home increase the level of education their children will attain, according to a 20-year study led by Mariah Evans.

For years, educators have thought the strongest predictor of attaining high levels of education was having parents who were highly educated. But, the study showed that the difference between being raised in a bookless home compared to being raised in a home with a 500-book library has as great an effect on the level of education a child will attain as the difference between having parents who are barely literate (有文化的) and having parents who have a university education.

Being a sociologist, Evans was particularly interested to find that children of lesser-educated parents benefit the most from having books in the home. What kinds of investments should we make to help these kids get ahead? The results of this study indicate that getting some books into their homes is an inexpensive way that we can help these children succeed. Evans said, “Even a little bit goes a long way. Having as few as 20 books in the home still has a significant impact on motivating a child to a higher level of education, and the more books you add, the greater benefit the children get.”

The researchers were struck by the strong effect having books in the home had on children's educational attainment even above and beyond such factors as education level of the parents, the father's occupation or the economic level of the country.

Having books in the home is twice as important as the father’s education level, and more important than whether a child was brought up in a developing country or a developed country. Surprisingly, the difference in educational attainment for children born in developed country and children born in developing country was just 2 years, less than two-thirds of the effect that having 500 or more books in the home had on children.

Many parents often say their teenage son looks like a grown   man.He is taller than his father，and his voice has turned deep.But his behavior is another matter.He makes hurried decisions, tries to smoke and drink，drives cars too fast and always makes his parents annoyed.Why?

That's because his brain is developing more slowly than his   body.Researchers at the National Institute of Mental Health and UCLA carried   out   a long­time   study   of normal   brain development.They found that the frontal lobe (大脑额叶 )，the area responsible for understanding future influences，making wise decisions and controlling impulses(冲动)，does not become mature (成熟的)until the early 20s.

Because of the immature brains，teenagers are easily influenced by the environment and unexpected behavior.So their death rates rise sharply.Research shows that rates of death by injury for people between the age of 15 and 19 are six times those seen in kids aged 10 to 14.The government reports that teens are four times more likely than older drivers to be involved in a car accident and three times more likely to die in one.

Teens may be attracted to drugs and alcohol.Rates of drug and alcohol use are high when compared with those of other age groups.Frances Jensen and David Urion，doctors at Children's Hospital Boston and Harvard Medical School，discovered that adult brain cells recovered (恢复 ) more quickly from alcohol influence than younger brain cells.Jensen said in Harvard Magazine: “For a teenager，what he drank on the weekend is still with him during that test on Thursday.”

Teens aren't making trouble on purpose.They long for freedom，but they are still young.They're still forming into the adults they'll eventually be.And，of course，they won't be at this age forever.Home education plays one of the most important roles in young people's growth，and the influence is most lasting.Finally，they will grow up and become wise adults.