📋 Tender Overview
As part of the studies of the behavior of microparticles suspended in the air that have been carried out in the laboratory the National Institute of Health INS of the Ministry of Health Minsa evaluates different types of fabrics with respect to their ability to act as a filter medium. of aerosols less than 5 m in diameter contagion route of COVID-19.The INS research chemist Manuel Chavez pointed out that the fabrics have holes in the intercrossings of the fibers with which they are manufactured the size of these holes varies according to the type of fabric being 100 - 200 m in the case of a cotton polyester or similar fabric whereby these free spaces would easily allow particles considered aerosols to pass which are less than 10 m in size.Likewise it was mentioned that the study has found however that there are other fabrics with smaller hole sizes such as cotton-based flannel drill type and non-woven ones known as notex. These fabrics have a weave with greater cross-linking reducing the size of the holes and the amount of them for which they present a greater filtration than the previous ones he specified.However he explained that in the case of the drill there is a problem of its low level of breathability which is why cotton flannel fabric and 60 g cm2 notex are the best for the protection of larger aerosols greater at 2.5 m in diameter. It has also been evaluated that the combination of fabrics or the number of layers slightly increases the level of protection. However it is not recommended that the mask have more than three layers because it could affect the level of breathability he said.Finally the specialist remarked that the use of fabric-based masks is not recommended in places of high exposure in those cases the use of KN95 respirators or the double mask surgical and a cloth on top is urged.
