With the new crown epidemic spreading to many countries, masks and other medical supplies into a global rush. But according to Reuters 10, Canada recently broke the news that millions of reserve masks have expired.
After the 2003 SARS epidemic, Ontario and the province's largest city, Toronto, stockpiled about 55 million N95 masks and other medical equipment in 2007 to deal with future outbreaks, according to official sources and documents learned by Reuters. However, the province's auditor general said in a report released in December 2017 that more than 80 percent of the province's stockpile of masks and equipment had expired. Officials with the province's Ministry of Health said the masks could be significantly less effective after they expire, and the CDC has previously recommended that expired masks be used only in cases of "crisis-level shortages.
Whether the expired masks still have a protective effect, can continue to use? Mr. Lin, head of a mask manufacturing company in Zhejiang, told the Global Times on the 11th that under normal circumstances, surgical masks are valid for three years, and N95 masks are valid for about five years, and the protective effect of the expired masks will gradually decrease over time.
Mr. Lin said the mask filtration effect mainly depends on the middle of the polypropylene meltblown nonwoven filter layer, the filter material mainly by electrostatic adsorption of fine particles, including viruses. But the amount of static electricity on the filtration layer is not always the same, with the mask to save time to extend, the static electricity on the filtration material will slowly weaken or even disappear, such as the filtration efficiency of the N95 masks should have reached 95%, static electricity gradually disappeared, the filtration layer may only have the effect of physical blocking, the protective ability to be greatly weakened. Mr. Lin also added that the filter layer is also afraid of moisture, water will also make its electrostatic charge reduction, greatly reducing the protective effect.
Mr. Lin told the Global Times that the validity of the masks is only guaranteed for three or five years. With the shortage of masks on the market today, masks that have not expired for a long time and have not been contaminated, broken or torn, or been exposed to moisture can continue to be used.
The U.S. media recently cited the Los Angeles County, California, Department of Health Industrial Senior Sanitation Division Francis Pierce, said that the ordinary environment, such as daily cleanup of the yard, environmental cleanup, expired masks can be used, but hospitals need to be carefully considered for special circumstances. In addition, worn masks can not be reused by washing and other means. As long as it is worn, it must be discarded. ▲
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