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  3. Children attending schools located in high-traffic zones have a 45 percent increased risk of developing asthma, even though time

Children attending schools located in high-traffic zones have a 45 percent increased risk of developing asthma, even though time

admin2011-03-11  44
问题     Children attending schools located in high-traffic zones have a 45 percent increased risk of developing asthma, even though time spent at school only accounts for about one-third of a child’s waking hours, according to new research.
    Asthma is the most common chronic childhood illness in developed countries and has been linked to environmental factors such as traffic-related air pollution. "While residential traffic-related pollution has been associated with asthma, there has been little study of the effects of traffic exposure at school on new onset asthma," says Rob McConnell, professor of preventive medicine at USC’s Keck School of Medicine. "Exposure to pollution at locations other than home, especially where children spend a large portion of their day and may engage in physical activity, appears to influence asthma risk as well."
    The study appears online in the journal Environmental Health Perspectives. The study drew upon data from the Children’s Health Study (CHS), a longitudinal study of children in Southern California communities that was designed to investigate the chronic effects of air pollution on respiratory health. Using a cohort of 2 497 kindergarten and first grade children who were asthma-free when they entered the study, researchers examined the relationship of local traffic around schools and homes to diagnosis new onset asthma that occurred during three years of follow-up. Traffic-related pollution exposure was assessed based on a model that took into account traffic volume, distance to major roadways from home and school and local weather conditions.
    Regional ambient ozone, nitrogen dioxide (二氧化氮) and particulate matter were measured continuously at one central site in each of the 13 study communities. The design allowed investigators to examine the joint effects of local traffic-related pollution exposure at school and at home and of regional pollution exposure affecting the entire community. Researchers found 120 cases of new asthma. The risk associated with traffic-related pollution exposure at schools was almost as high as for residential exposure, and combined exposure accounting for time spent at home and at school had a slightly larger effect. Although children spend less time at school than at home, physical education, and other activities that take place at school may increase ventilation rates and the dose of pollutants getting into the lungs, McConnell notes. Traffic-related pollutant levels may also be higher during the morning hours when children are arriving at school.
    Despite a state law that prohibits school districts from building campuses within 500 feet of a freeway, many Southern California schools are located near high-traffic areas, including busy surface streets.
    "It’s important to understand how these micro-environments where children spent a lot of their time outside of the home are impacting their health," McConnell says. "Policies that reduce exposure to high-traffic environments may help to prevent this disease. " The study was funded by grants from the National Institute of Environmental Health Sciences, the US Environmental Protection Agency, the South Coast Air Quality Management District, and the Hastings Foundation.
We can infer from McConnell’s view that______.
选项 A、there has been little study of the residential traffic-related pollution
B、activities that take place at school may increase the risk of asthma
C、traffic-related pollutant level is lower during the morning hours
D、frequent exposure to outdoors appears to influence the risk of asthma
答案B
解析 本题的关键词是McConnell。文章第四段倒数第二句提到了麦康纳尔的观点：虽然学生待在学校的时间比待在家里的时间短，但是体育锻炼和其他的学校活动会提高呼吸频率，大量污染物进入肺，从而增加患病风险，故[B]正确。文章第二段第二句提到住宅区的交通污染与哮喘病相关，但却很少研究暴露在交通密集区的学校对哮喘病发病的影响，故[A]不正确。第四段末句提出，清晨孩子们到学校的时候与交通有关的污染物浓度可能更高，[C]与文意相反，故错误。文章并不是说暴露在外面就容易患哮喘病，而是接触交通密集区会增加患哮喘病的风险，[D]是对文章意思的曲解。  
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