However, there was a previous news in Moments that 'the anti-smog masks purchased online are useful for anti-smog, but the formaldehyde exceeds the standard'. Many users who have the habit of wearing masks for themselves or their children are very worried. Does the mask that is worn by the mouth every day really protect against PM 2.5, but inhale formaldehyde? The engineers in the laboratory bought 6 high-selling protective masks and went to the textile laboratory of CVC Weikai Shunde Base to find out. From November 1, 2016, the General Administration of Quality Supervision, Inspection and Quarantine and the National Standardization Administration have issued GB/T 32610-2016 'Technical Specifications for Daily Protective MasksIn order to ensure the safety of the public wearing protective masks, the standard clearly stipulates the protective effect and wearing safety performance of fine particulate matter (PM 2.5). According to the requirements of this regulation, all masks produced in accordance with the new national standard not only need to be test
ed before being marketed. In addition to the 'protective effect1 Test whether it contains formaldehyde The harm to the human body of formaldehyde has been widely known. The new national standard requires that the formaldehyde content of protective masks should be less than or equal to 20 mg/kg. However, if the mask is in contact with the face, too high or too low pH may cause discomfort to the human body. Therefore, the new national standard also stipulates that the pH range should be 4.0 to 8.5. So why is there formaldehyde in masks? ①It may be that the textile used in the mask itself contains formaldehyde; ②It may be that glue is used during the processing of the mask, and the glue adheres to the textile; ③It may be that the filter or vent in the anti-haze mask has plastic, which is used in plastic processing. Chemical substances containing formaldehyde. Therefore, when we sample the mask test, we take samples from multiple parts of the mask. We divide a mask into multiple parts such as the main cloth, hanging ears, and viscose, and sample one by one to detect the formaldehyde content in it, so that the results obtained are more detailed. At the beginning of the test, the mask sample to be tested is cut into small pieces. The sample is about 1 g. Then, add the sample to pure water, then put it in a constant temperature shaking water bath, and shake it under 40 ℃ warm water for 1 h. This is mainly to fully dissolve the formaldehyde component in the sample. After 1 h, take out the sample, and add a color developing agent for color reaction, the purpose is to dissolve the formaldehyde. After another 0.5 h, test the sample with an ultraviolet spectrophotometer, the absorbance value can be measured, and the absorbance value is finally converted into a concentration, and then it can be calculated whether the formaldehyde exceeds the standard. 2 Test whether it contains azo azo dyes refers to the dyes containing azo groups in the molecular structure, which are the most diverse and widely used synthetic dyes. Azo dyes are used for dyeing and printing of various fibers, and for dyeing leather, paper, soap, candles, wood, wheat straw, feathers, etc., as well as coloring paints, inks, plastics, rubber, food, etc. According to relevant experts, more than 20 kinds of carcinogenic aromatic amines are listed in the national standard. Clothing containing decomposable carcinogenic aromatic amine dyes will spread in the human body if they are absorbed by the skin during long-term contact with the human body. Human body pathology and induced cancer. In the new national standard, azo dyes are banned for masks. Generally, non-colored anti-PM 2.5 masks do not contain azo threats. What needs to be vigilant is some colored fabric masks. Especially masks with dark colors such as black and red are more likely to contain azo. The azo test is relatively complicated. First, cut out 2 g of the hood sample, and add sosso to reduce the azo component. Then, use ether for component extraction, followed by rotary evaporation. The purpose of this test step is to evaporate the ether to dryness, leaving the dye components behind. The components left in this way can be tested with a gas chromatography-mass spectrometer, and a spectrum will be obtained. In terms of azo, the new national standard test standard cannot be detected. In Figure 1, the engineer detects azo and adds a chemical reagent to the glass tube where the sample is placed. 3 Test the pH value. Since various acid-base additives are added to the textiles during processing, some manufacturers have omitted the steps of adjusting the pH of the textiles in order to save costs. The PH value of human skin is usually 5.0 to 6.5. If the fabric touched is too acid or alkali, it will cause harm to human skin and cause skin allergies and other uncomfortable symptoms. In masks, the standard space for PH value is between 4 and 8.5. In the test to test the pH value, firstly, 1 to 2 g of the mask sample will be cut out, and pure water will be added to dissolve it. Then, place the sample in a constant temperature shaking water bath and shake at room temperature for 2 hours. After filtering, the sample is directly tested with a pH meter. Two days later, the test results came out! It can be seen that the formaldehyde and PH value of the 6 masks purchased did not exceed the standard (see Table 1). Although the tested masks contain traces of formaldehyde, the content of these formaldehydes is within the national standard, so it will not threaten human health. 4 Precautions for the purchase of masks 1) It is recommended to purchase through formal channels; 2) When purchasing, pay attention to whether the product identification is clear (including manufacturer name and address, product name, product specifications, relevant standard certification, protection effect level, implementation standard number, Product instructions, production date, recommended time of use and storage period, etc.), it is necessary to check whether the appearance is stained, deformation that affects use, etc.; 3) According to different air pollution levels, select masks with corresponding protective effect levels; 4) Select for the first time When using masks, please refer to the current product instructions to try them on, and purchase products that have a good fit on the face;
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