The face masks with bacterial filtration efficiency (BFE) above 95 percent are the safest ones.

BFE measures the percent efficiency at which the face mask filters bacteria passing through the mask.

'Generally the face masks available in the market do not have proper filters and it is no use wearing them,' said a research scientist.

Doctors says there are several things that should be kept in mind while using face masks like washing hands before wearing and after removing it.

'The mask should be worn in such a manner that the nose and mouth is properly covered. People should be safe behind the mask. It should be tied in a manner that there are no openings as infection could easily enter the body,' he said.

Guleria said there are three types of masks - single-layered (surgical mask), three-layered mask and the N95.

'The N95 masks are considered to be the best as they offer 95 percent protection from virus. The side that touches users' faces should not be touched. They should tie and take it off without touching that side. It should be disposed off immediately and thrown in the dustbin.

The same thing should be done to the tissue paper. The tissue should not be kept on the table. The infection is easier to spread that way. They should not lie around,' said Guleria.