at least 200 feet

Children who lived within 75 meters of a major road  were approximately 1.5 times more likely to report asthma or wheezing compared to those living 300 meters or more from a major road. Among children with no parental history of asthma, those who had resided at an address close to heavy traffic since before age 2 experienced even higher risks (2.5-fold for asthma and 2.7-fold for wheezing), suggesting that a cumulative lifetime exposure to traffic pollutants may raise health risks.

California recently passed a law that prohibits the construction of new schools within 500 feet of freeways.

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200米還有噪音嗎 -途中燕子- 給 途中燕子 發送悄悄話 途中燕子 的博客首頁 (0 bytes) () 02/27/2012 postreply 11:49:00

建議你 -美西遊子- 給 美西遊子 發送悄悄話 美西遊子 的博客首頁 (129 bytes) () 02/27/2012 postreply 12:03:24

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