The large difference of HEPA air purifier test report—Home Air Purifier
June 17, Xicheng District Education Commission on the smallest Baiyun Road Campus playground full demolition, construction workers are on the school playground plastic runway demolition. The Beijing News reporter Wang Guibin photo
Two respectively by the government and parents commissioned indoor air quality monitoring report, let Beijing No.2 Experimental Primary School of Baiyun Road, once again attracted attention.
China environmental monitoring station monitoring report shows that in the sampling and monitoring of 16 classrooms, only a music classroom detected formaldehyde exceeding 1 times, and in some parents entrust social testing institutions to provide report shows, monitoring of a sample of 16 classrooms, indoor air formaldehyde content exceeded, exceeding the average more than 3 times, which a music room formaldehyde concentration of 2.283 mg / m3, exceeding 22 times.
Recently, some media reported that some parents was commissioned by the government of Xicheng District Environmental Monitoring Station of China the school indoor air quality monitoring report questioned think monitoring station to pick the wrong analysis method, and therefore can not effectively detect formaldehyde content in the classroom. Yesterday, China Environmental Monitoring Station in its official website issued a statement of a response.
Focus 1: why the same classroom, two institutions to monitor the concentration of formaldehyde are a far cry from? China environmental monitoring station is wrong analysis method?
“Detection method is one of the four standard recommended”
According to media reports, in the two monitoring has 6 classrooms coincidence. Why the same classroom, the two agencies to monitor the concentration of formaldehyde are a far cry from?
Reported that two institutions selected for formaldehyde evaluation standard is consistent, the difference mainly lies in the inconsistency in the analysis methods of formaldehyde. The report pointed out that China environmental monitoring station selected < Acetylacetone Spectrophotometric method > was enacted in 1995. The report said, “for this is the presence of high concentrations of formaldehyde in indoor air”.
In this regard, the China environmental monitoring station, said to see the report after the start of the internal technical review process.
In view of the problem of formaldehyde analysis method selection, China Environmental Monitoring Station said that the current “indoor air quality standard > recommended formaldehyde analysis method of 4 kinds, 4 methods of the same effect.
According to the method in 0.5 sampling to 10 liters, the measurement range is 0.5 ~ 800 mg / cubic meters of. China Environmental Monitoring Station said that the measuring range of lowest value (detection limit) is an analysis conditions are determined by the sampling volume and the specific experimental, usually sampling volume is larger, can be used to determine minimum value detection lower limit. The monitor, the actual sampling 45 liters, which combined with experimental conditions to determine the formaldehyde detection limit of 0.03 mg / m3, meet the needs of this monitoring. Monitoring of a sample of 16 classrooms, there are 13 monitoring results were below the limit of detection, so a unified representation for 0.03L.
Focus 2: in the detection of social organizations to provide the test report, the highest concentration of formaldehyde in the room more than 22 times, which means that what?
“If the standard 22 times people can not stay indoors”
The China disease prevention and control center researcher Liu said, standards of indoor air, formaldehyde concentration limit to 0.10 mg / m3. When the indoor formaldehyde concentration exceeded the standard, you will smell the pungent odor, causing sensory discomfort.
Liu fan, under normal circumstances, the new decoration of the family housing, formaldehyde concentration detection results are usually not more than 0.40 mg / m3. Liu said, indoor formaldehyde concentration greater than 2.0 mg / m3, the staff did not in the room stay.
And according to participate in on-site monitoring station technical personnel, in addition to music in the classroom, some smells, other classrooms didn’t feel obvious smell, the body has no obvious symptoms. Therefore, the community inspection agency issued the report detected high concentrations of formaldehyde value, at present is still in doubt.
China environmental monitoring station is a national environmental monitoring agencies, research center for eco environmental sciences researcher Zheng Minghui said: “as far as I know, they to the school classroom air quality monitoring is carried out in strict accordance with the relevant standards.”
Zheng Minghui said that in the process of monitoring, Xicheng District Education Commission, representatives of parents and the notarial institution of closed classroom and field sampling and other aspects of supervision and, equipment and qualified personnel are in line with the requirements, monitoring report stamped with the CMA chapter, with the force of law. “I think the results are credible”.
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