BHUBANESWAR: A study conducted by researchers from the Institute of Minerals and Materials Technology (CSIR), Bhubaneswar, has found that the efficiency of the six-layered N95 mask reduced more than the simple N95 mask after being washed with detergents.
Surgical masks saw the most reduction in filtration capacity after a wash.
The findings of the studycalled ‘Evaluating filtration efficiency of commercial face mask materials against respiratory aerosol droplets’ was published in the ‘Journal of the Air and Waste Management Association’. It revealed that the efficiency of the six-layered N95 mask reduced by three per cent after washing, while that of the surgical masks dropped by 11%.
According to the study, the filtration efficiency of the N95 mask without valve reduced by two per cent after a detergent wash, while it reduced by four per cent in a KN95 mask, three per cent in an N95 mask with valve and 4% in a heavily-knitted cotton mask. It came down by 11% in a two-layered cotton mask, by six per cent in a double-layered nylon fabric mask, a double-layered T-shirt fabric each by eight per cent in a single-layered T-shirt fabric mask.
“We conducted the experiments in an acrylic chamber and observed the filtration capacities of the masks at different levels under different conditions,” Trupti Das, principal scientist at IMMT Bhubaneswar, said. Das was part of the five-member research team, which was led by senior scientist Dr Ramaswamy Boopathy.
She said a variety of masks in different shapes, forms, designs and materials are available in the market nowadays. Face masks have become a clothing accessory as well as a fashion trend. It is primarily due to the prevailing pandemic situation now but face mask are also very useful to be saved from air pollution, she said.
In this context, the researchers have made an attempt to study the filtration efficiency of the commonly available commercial masks. The study also revealed that 6-Layer N95 mask has the maximum filtration efficiency followed by N95 mask without valve, KN95 mask, N95 mask with valve, heavy knitted cotton mask, surgical mask and cotton mask-2 layers.
It is observed that increasing the knitting stitches in cotton masks tends to improve its filtration efficiency through the material. However, after washing the results were different. So we recommend the usage of multi-layered N95 masks followed by N95 masks without valve, KN95 or N95 with valve masks and others based on their efficiency, the scientist added.
