The Technical Specifications for Gravimetric Measurement Method for PM_(2.5)in Ambient Air clearly state that particulate samples must achieve constant weight at specified temperature( 15—30 ℃) and relative humidity( RH,45% —55%) ranges. Thus,an immediate process of dehumidification and tempering treatment was significant in the PM_(2.5)online monitoring field. A set of dehumidification and regulating temperature system of monitoring ambient air particulate matter mass concentrations sampling was developed,...