The atmosphericconcentration of methyl chloride (CH 3Cl) is very low, only at 10 -12 (V/V) level.
氯甲烷在大气中的浓度较低，仅为10 -12 级别。
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Now that the gas is no longer being produced, scientists can more accurately gauge the action of hydroxyl upon methyl chloroform's atmosphericconcentration.
Human activities has result in the increase of atmosphericconcentration of greenhouse gases, which is concerned as a main cause of the global climate change.