It is mere a psychological re-assurance to medical fraternity, especially nurses and the most visible traffic cops in cities who wear them religiously but not realising that they are durbious and ineffective giving them a false sense of security, scientists have warned.
Researchers at the University of Massachusetts Amherst, in a first of its kind study, tested disposable surgical masks and washable cloth masks, which are widely used in Asia and China and other Southeast Asian nations to keep away from airborne particulate matter.
“They assume that they are protected from these contaminants,” said Richard Peltier from University of Massachusetts.
Initially, the study was done during an air quality research project in Nepal that researchers realised how people wore surgical or reuseable cloth masks on the street owing to poor air quality, resulting from high polluting gasoline and diesel engines, besides burning tyres and garbage.
“We found ourselves wondering how effective these masks are. I was shocked that we couldn’t find any research studies investigating them,” Peltier said.
Though the standard industrial hygiene mask known as the N95 is well tested, they are not readily available or too expensive for most consumers. Researchers tested four masks: one pleated surgical type, two cloth and one cone-shaped cloth with exhalation flaps.
They tested for filtering five different synthetic aerosol particle sizes plus three particle sizes of diluted whole diesel exhaust, which simulated real-world conditions.
Among the cloth masks, the mask with exhaust valves performed fairly well, removing 80-90 per cent of synthetic particles and about 57 per cent of diesel exhaust but plain cloth masks beneficial only in protecting from particles smaller than 2.5 micrometres, often considered more harmful.
The cloth masks removed just 39-65% of standard particles of 30, 100 and 500 nanometres, and one and 2.5 micrometres. But all masks failed to filter diesel combustion particles compared to monodispersed particles, the researchers said.
The study was published in the Journal of Exposure Science and Environmental Epidemiology.