TIFR develops country’s first low-cost mask testing equipment
The Tata Institute of Fundamental Research (TIFR), Mumbai, has developed India’s first low-cost testing equipment to assess the efficacy of masks.
Considering the shortage of personal protective equipment (PPE), including masks, for frontline health workers during the Covid-19 pandemic, TIFR is also studying how N95 masks designed for 95% filtration efficiency for very small 0.3 micrometre (µm) sized particles, can be reused after decontamination.
A team of scientists led by professors Arnab Bhattacharya and Shankar Ghosh of TIFR, along with Ronak Sutaria of air quality research group Respirer Living Sciences (RLS), built a prototype - mask integrity test resource (MITR) - using air quality measurement units and other components to develop a setup that measures fine particle (0.3µm) filtration through N95 masks. This was built during the lockdown using items such as a vacuum cleaner, boxes, bottles, and a plastic ball (used as a mannequin).
“We estimate that such a unit could be built for Rs. 30,000-50,000 ranging from the most basic one to a slightly advanced unit within the country,” said Bhattacharya. “Commercially available units that need to be imported cost over Rs. 10 lakh. At the same time, recent US Federal Emergency Management Agency (FEMA) guidelines restrict the export of PPEs, which will impact the availability in India.”
For the project, different types of N95 and surgical masks being used by Tata Memorial Hospital in Mumbai were supplied to TIFR, and were tested using this equipment. The filtration efficiency could drop significantly if the mask was not well fitted, and allowed leaks from the side, Bhattacharya said while cautioning that these experiments were done using a rudimentary set up on a plastic ball. “While we expect a better fit for the human face, we found that even if the best N95 masks are used unless the mask is worn properly or sealed well from the sides, it can be dangerous for frontline workers,” he said.
The TIFR scientists also evaluated the filtration efficiency of several materials used at home for masks – from folded handkerchiefs to cotton T-shirts. “Even home-made masks could have 50-60% filtration efficiency, comparable with surgical masks, and are good for everyday use by the public,” said Bhattacharya.
The testing protocol plays a critical role in evaluating the efficiency of masks across intensive care units (ICUs) and health care facilities, said Sutaria. “Many hospitals across India are currently facing a severe shortage of facemasks, leading to the manufacture of varying quality. The existing mask testing equipment available from the US costs upwards of Rs. 12 lakh up to Rs. 90 lakh. Masks are going to be required not only during Covid-19, but for all kinds of infections and epidemics,” he said, adding that such a low-cost set up could also help in quickly comparing the quality of masks, with the risk of the market being flooded with inferior quality products.
The other aspect of TIFR’s research looked at reusability of masks after disinfecting them.
According to N95decon.org, an international consortium of scientists and researchers for N95 mask decontamination, alcohol based disinfectants, soaps or detergents, bleach solutions, ethylene oxide etc. though effective in virus inactivation could degrade the filtration efficiency or leave hazardous residues. However, moist and dry heat treatment, hydrogen peroxide vapour, ozone, and ultraviolet radiation were useful.
A major contributing factor that enhances filtration efficiency was a layer of electrically charged fibres that trap particles in N95 masks, TIFR researchers found. The charge diminishes significantly when cleansed using alcohol based solutions. Researchers developed a procedure to recharge these N95 masks. “We believe recharging could allow recovery of the filtration efficiency of used masks, allowing them to be reused for relatively longer periods than the current norm,” said Ghosh.
Frontline Covid-19 warriors from private and municipal hospitals in Mumbai are following a procedure wherein four to five N95 masks are being provided for every 20 days to each person. “A worker will use a mask a day, sterilise it after use, store it safely at the end of the shift, and reuse it again after five days. The same process is repeated for each mask until a new set is supplied,” said a doctor from Nanavati Hospital.
A senior surgeon from King Edward Memorial (KEM) Hospital in Parel said, “We get four masks for 20 days. We steam the mask before reusing it on the fifth day. Over the past week, health workers dealing with Covid-19 patients in the ICU are getting a new mask every day, and the used ones are discarded daily.”
Researchers at TIFR and RLS managed the development of the mask testing technology in a matter of days amid restrictions during the lockdown. As TIFR was developing the mask testing prototype, they got in touch with RLS to use their low cost air pollution monitoring units, which were supplied within a day. Over just one weekend, TIFR researchers along with RLS managed to develop testing principles, completed their prototype, and were ready to do tests to evaluate filtration efficiency of masks for front-line health care workers.