A gas coming into contact with a base material or substrate is purified by dust removing apparatus and adsorption and absorption apparatus so that the concentration of fine particles in the gas is below class 1,000 and {TAIL ~ a non methane hydrocarbon concentration} is below {HEAD ~ 0.2 ppm} 
A gas coming into contact with a base material or substrate is purified by dust removing apparatus and adsorption and absorption apparatus so that the concentration of fine particles in the gas is below class 1,000 and { TAIL ~ a non methane hydrocarbon concentration } is below { HEAD ~ 0.2 ppm }
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