[Policies and Standards of Chemical Industry Instrument Network] In China, VOCs refer to organic compounds with saturated vapor pressure greater than 70 Pa at normal temperature and boiling point below 260 ℃ at normal pressure, or all volatile organic compounds with vapor pressure greater than or equal to 10 Pa at 20 ℃. VOCs are generally classified into non methane hydrocarbons, oxygen containing organic compounds, halogenated hydrocarbons, nitrogen containing organic compounds, sulfur containing organic compounds, etc. VOCs participate in the formation of ozone and secondary aerosols in the atmospheric environment, and have made important "contributions" to the formation of regional atmospheric ozone pollution, PM2.5 pollution and photochemical smog. Moreover, most VOCs have unpleasant odor and toxic, irritating, teratogenic and carcinogenic effects.

As an important source of VOCs in the atmosphere, it is imperative to monitor the concentration and total amount of VOCs emitted by industrial emissions. At present, automatic monitoring, as an effective monitoring method for organized emissions, has relatively mature technology, which can achieve continuous monitoring of non methane total hydrocarbon (NMHC), a comprehensive pollutant indicator of VOCs from industrial emission sources. Ultra low emission dust meters have also carried out online monitoring of non methane total hydrocarbon pollution sources in many provinces and cities. It is urgent to guide ranking units to operate online monitoring facilities for non methane total hydrocarbon pollution sources through standardization, Carry out data audit according to specifications to ensure the authenticity, accuracy and reliability of online monitoring data, better play the role of online monitoring, and provide effective support for environmental quality improvement and environmental management.

In order to implement the overall deployment of the Notice of the State Council on Printing and Distributing the Three Year Action Plan to Win the Battle of Blue Sky (GF [2018] No. 22), standardize and guide the construction and operation of VOCs automatic monitoring facilities, further improve the quality of VOCs pollution source automatic monitoring data, and better play the role of automatic monitoring in environmental supervision and law enforcement, in April 2019, The Ministry of Ecology and Environment issued the Technical Guidelines for Continuous Monitoring of Non methane Hydrocarbon Emissions from Fixed Pollution Sources (Trial) (Draft for Comments).

This technical guide is applicable to the construction, operation and management of the continuous monitoring system for non methane total hydrocarbons in the exhaust gas from fixed pollution sources. The ultra-low CEMS system document specifies the composition, function, technical performance, monitoring station, installation, technical index commissioning and detection, technical acceptance, daily operation management Relevant requirements for daily operation quality assurance and data review and processing.

This technical guide is helpful to promote the standardization and standardized construction and operation of VOCs pollution source online monitoring system, and is also helpful to improve the pollution source monitoring technical system.