China Environmental Monitoring Station quietly issued the "PM2.5 automatic monitoring instrument technical indicators and requirements (on trial)" (hereinafter referred to as "indicators and requirements") in order to guide the first phase of PM2.5 monitoring capacity building.

According to the Implementation Plan for the First Stage Monitoring of New Air Quality Standard issued by the Ministry of Environmental Protection on May 24 (hereinafter referred to as the “Implementation Plan”), key regions such as Beijing-Tianjin-Hebei, Yangtze River Delta, and Pearl River Delta, as well as municipalities directly under the Central Government and provincial capitals Cities in key regions such as 74 cities will have to carry out monitoring of new indicators for the “Ambient Air Quality Standards” (PM2.5, CO, O3, etc.) by the end of this year.

Previously, it was reported that on the PM2.5 auto-monitoring technology route, the oscillating balance method monitoring results were 15%-17% lower than the ray method, which was also the reason why the Beijing Environmental Protection Agency was lower than the US Embassy monitoring data last year. One (Beijing Municipal Environmental Protection Agency monitoring equipment using oscillation balance method, the United States Embassy monitoring equipment using ray method).

The above debate can be calmed down. The "Indicators and Requirements" indicate that both routes are acceptable, but they must meet certain technical standards. The head of a local environmental monitoring station pointed out to reporters that this means that the procurement of PM2.5 automatic monitoring equipment nationwide will start on a large scale.

At the same time, the China National Environmental Monitoring Center also gave guidance on the monitoring technology route of PM2.5.

"Indicators and Requirements" have identified three methods for automatic monitoring of PM2.5. They are the ray method instrument plus dynamic heating system, ray method instrument plus dynamic heating system combined with light scattering method, micro-oscillation balance method instrumentation film dynamics. Measurement System (FDMS).

At the same time, according to the results of the comparison tests conducted in the first phase at the same time in Beijing, Shanghai, Chongqing, Guangdong, Jinan, etc., for the PM2.5 auto-monitoring method instruments participating in the test, the micro-oscillation balance method instrument must be installed with membrane dynamics. Measurement systems and ray method instruments must be equipped with a dynamic heating system in order to meet the requirements of the test parameters.

Previously, it was reported that the micro-oscillation balance monitoring method was 15%-17% lower than the ray method. Both methods are correct in terms of measurement principle. It cannot be said in general whether it is too high or too low. Certain errors are allowed. However, we can reduce the error by technical means as much as possible. Wang Ruibin, Director of Atmospheric Office of China Environmental Monitoring Station, explained to this reporter.

Wang Ruibin further pointed out that the micro-oscillation balance method must be equipped with FDMS, ray method instruments must be installed dynamic heating system, if you do not add the supporting device, then this monitoring product is incomplete, the data may be larger error.

For the previous PM2.5 monitoring point, if no compensation device is added, it shall be filled in; after the monitoring point of the new PM2.5 monitoring instrument is newly added, the compensation device shall be installed when purchasing the monitoring instrument. An official from the Monitoring Department of the Ministry of Environmental Protection introduced the reporter.

However, Zhou Xiaobin, China's commercial director of the Ministry of Environment and Process Instruments Division of Thermo Fisher, stated that in the United States, PM2.5 monitors from oscillatory balances do not necessarily have to be equipped with FDMS. Each state can freely choose whether or not to install FDMS. Post-installation monitoring results are considered to be Federal Equivalent Methods (FEM) results, and monitoring results without FDMS are PRE-FEM results. Whether or not it is installed, it needs to be calibrated with the federation reference method, but the frequency of calibration is different. The FEM is calibrated once every three days and the PRE-FEM is calibrated once every six days.

According to Wang Yuesi, Institute of Atmospheric Physics, Chinese Academy of Sciences, in the use of FDMS in micro-oscillation balances, the environmental conditions in some areas of China have caused FDMS to be used in some areas of China, and many cities have high concentration of fine particles and high fine particles. The pores that cause FDMS's permeable membrane are quickly blocked by fine particles, which reduces its service life to half that of foreign countries, and may be replaced once in 2-3 months.

Permeable membranes cost about $1,000, which is not a small cost for many monitoring stations. Wang Yuesi introduced that FDMS is not suitable for wet areas in the south or cities that are heavily polluted.

Fu Qingyan, chief engineer of the Shanghai Environmental Monitoring Center, publicly stated that any kind of automatic monitoring method has its own advantages, disadvantages, and applicability. What is important is that a city’s own method system must have continuity and comparability. Do not change it easily. method.

In addition, Wang Ruibin emphasized to this reporter that "Indicators and Requirements" currently only apply to PM2.5, and PM10 issues are not considered for the time being. In other words, PM10 monitoring equipment does not require additional compensation devices.

Because the monitoring platform for the applicability of PM2.5 monitoring instruments is still under construction, the China National Environmental Monitoring Center adopts internationally universal monitoring instrument testing and evaluation methods. From November 17, 2011 to March 27, 2012, the terminus The Atmospheric Monitoring Integrated Laboratory conducted the first phase of applicability comparison testing for the PM2.5 monitoring instruments that are mainly used by particle production monitoring equipment manufacturers in China.

The results showed that there were 6 models of corresponding models produced by 5 production companies that met the guidance requirements of the tests. They were Beijing Zhongyu Tyco 7021 ray plus dynamic heating system method PM2.5 monitor; Hebei Xianhe Environmental Protection XHPMat2000 Type ray plus dynamic heating system method PM2.5 monitor; MetOne Instruments BAM-l020 ray plus dynamic heating system method PM2.5 monitor; Thermo Fisher TEOM-1405F type micro-oscillation balance film dynamic measurement system method PM2.5 monitor and 5030-SHARP type ray plus dynamic heating system combined with light scattering method PM2.5 monitor; Wuhan Tianhong Instrument TH-20OOPM type ray plus dynamic heating system method PM2.5 monitor.

Compared with the list of 9 products of the 6 companies involved in the inspection, some of the products of some companies failed to be represented. They are the PM2.5 automatic monitor of the TEOM1405 and FH62C14 of the Thermo Scientific company in the United States, and the oscillation balance method monitor of the Anhui Bluetron Optoelectronics. The aforementioned station of the local environmental monitoring station introduced this reporter.

The headmaster pointed out that the above-mentioned instruments that participated in the first phase of testing in each test area, but have not yet reached the test validity date, will continue to carry out tests in the subsequent stages, and will perform the assessment after reaching the number of test days.

The test equipment is a factory inspection equipment, not a sampling equipment, there is a problem of manufacturer selectivity. An expert who is close to the China National Environmental Monitoring Center pointed out that other monitoring instruments that failed to participate in the first phase of testing for various reasons and are not within the scope of this assessment will be tested in the subsequent phase of testing or future instrument suitability testing. Capacity or formal testing procedures are gradually included in the scope of assessment and selection.

The aforementioned experts emphasized that this PM2.5 automatic monitoring instrument comparison test is a temporary transition, but only for the reference of the first phase of the "Implementation Plan" monitoring and procurement, and can not replace the formal monitoring instrument suitability test. After the establishment of the certification platform of the environmental monitoring instrument quality inspection center of the Ministry of Environmental Protection, all particle monitoring instruments used by the environmental air quality monitoring websites of all countries will be subject to formal applicability testing.

According to the “Indicators and Requirements”, the China National Environmental Monitoring Center will continue to conduct a one-year comparison test. In subsequent tests, the equipment failure rate will be included in the test index to ensure that the 90% of the data in the new standard is satisfied. .