塑膠袋比較環保?!

最近聽到這樣的結論
讓一直以來認為紙袋環保的我驚訝不已
認為紙袋環保原因：
紙袋可以回收再利用，並且當掩埋到土裡後可以自然分解
但是塑膠袋燃燒會產生有毒氣體，掩埋後永遠不會消失
基於以上原因，怎麼想都會認為紙袋比較環保
但是最近聽到的消息是從另一個層面思考的
在生產紙袋的過程中有幾個步驟需要高溫環境
因此需要消耗大量的能量在此上面
並且塑膠袋比紙袋相對來說來的耐用
可以使用比較長期或多次
因此以平均來說，利用塑膠袋所消耗的單位能源較少
也比較耐用.
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I heard a novel finding which makes me astonished.
I thought it's more environmental friendly to use paper bags
rather than plastic bags for the reasons below. First paper bags
are recyclable and decomposed after being buried.
On the contrary, plastic bags will create toxic air after they are burnt.
However, this maybe wrong if we think this problem from another point of view.
Making paper bags consumes more enery than making plastic bags.
Furthermore, plastic bags are more durable than paper ones.
Thus, on the average, the plastic bags are more environmental friendly
than paper bags.