As at Beijing at 21:00 on May 2020 on the 6th, the new crown pneumonia patients worldwide have totaled 3,751,966 people, and caused 259 209 deaths. Close droplet transmission, contact transmission and spread of aerosols are three main modes of transmission of the new crown pneumonia, and three modes of transmission are needed to reach the lungs through the respiratory tract of a new host, and then the formation of infection. Therefore, wearing a mask is the best way to reduce the risk of the sensor. Currently protective effect is better masksN95 masks, however, due to the raging global epidemic led to the surge in demand for N95 masks and N95 mask production supply chain is damaged due to a significant reduction in the current epidemic is serious country, N95 masks has become a luxury, there has been a lot of short supply situation. In order to alleviate this serious situation, even the US President Trump also recognized: to increase the number of N95 masks can be sterilized using masks! So, what disinfection method not only ensures that the protective effect of N95 masks, and conditions applicable to the majority of ordinary families do? To solve this problem, Stanford University professor Yi Cui research team gives the answer in the latest issue of \”ACS Nano\” in:
(1) a simple heat treatment (temperature between 75 ~ 100 ℃, time between 5 ~ 30min, the lower the temperature, the longer the processing time) can be well maintained masks N95 filtration efficiency (> 95%). The post-treatment 20 times (20 min) at a temperature of 85 ℃, humidity of 30% for filtration efficiency N95 masks still up 96.79%. (2) ultraviolet irradiation treatment (254 nm, 8W) N95 masks filtration efficiency may be maintained at a low condition number of cycles. When more than 10 times treatment cycles, began to significantly decrease the efficiency of the filter; after 20 treatments, N95 masks filtration efficiency of only 93%. (3) N95 masks directly immersed in a disinfecting solution will significantly reduce the filtering efficiency of the mask. As N95 mask after immersion in 75% alcohol out quickly, reducing the efficiency of filtration and drying, masks to 56.33%.
The study of anti-virus sterilization methods were several home test and evaluate, recommend N95 masks are given a preferred method of disinfection. In this period of rapid spread of the infection, to alleviate the shortage of N95 masks pressure has a positive role in promoting. The studyEntitled \”Can N95 Respirators Be Reused after Disinfection? How Many Times?\” Papers published in \”ACS Nano\”. (Link attached description)
[N95 masks and protective structure Principle]
the results show that moisture meltblown filtration efficiency of the heating treatment is not too large effect, and the heating temperature at the time interval 75 ~ 100 ℃, several meltblown after the cycle test, filtration efficiency can be well maintained. After the treatment, for example, 20 times (20 min) at a temperature of 85 ℃, humidity of 30% for filtration efficiency N95 masks still up 96.79% [FIG. 4 (B) and (C)]. But will reduce the static charge content of the fiber temperature is too high, this may be a high temperature that the fiber polarization state to a relaxed state due to recovery. Finally, the authors studied the UV treatment on circulating meltblown filtration efficiency, it found that too much static charge cycle can lead to decreased amount of fiber, which led to decreased filtration efficiency. For example, after the 254 nm, ultraviolet radiation and other 8W processing cycle 20 times, meltblown filtration efficiency dropped to 93%, the N95 is lower than the standard.