Although poor syntax and spelling in the labelling are hardly indicative of a face mask's ability to protect people, they certainly point to a questionable provenance.

And that seems to be just the case with N95 masks issued to medical personnel at the Bangabandhu Sheikh Mujib Medical University Hospital on Saturday.

The warning on the masks reads, "This respirator Protects agalnst cortein Panrticles. Misuse may result insickness ordeath. For proper use see supervisor orbox or can 3M…"

It is highly unlikely that 3M, one of the world's biggest suppliers of respiratory protection, would release products with such a ridiculous text. There are two instances of mid-sentence capitalisation, the words against, certain, particles and call are misspelled and there are three instances of a deleted space between words -- and all of that in just 23 words.

Doctors who were handed the masks said it was easy to tell that these were counterfeit products.

"The build quality is poor. Texture of the material and the structure is different and shabby," said a doctor who had compared an N95 made by 3M with the one given by the hospital.

He and several other resident physicians, wishing anonymity, blamed the hospital for handing them fake masks to treat Covid-19 patients.

They have complained on Saturday to the hospital director and the authorities concerned about the matter.

Each resident doctor treating Covid-19 patients was given five N95 masks to use over a week. The doctors said a few of the masks seemed authentic, but most of them were obvious knockoffs.

"Is it possible to find such spelling errors in a high-end product like N95?" a resident doctor asked.

Another doctor said during the orientation programme for the Covid-19 doctors earlier this month, officials promised the doctors of N95 masks and other protective equipment for treating the coronavirus infected patients.

"If proper PPE [personal protective equipment] was given to us, we would have no problem working," said a doctor.

The director's office was tasked with purchasing the masks and PPE and ensuring the quality of the products.

"But the authorities have failed us," another doctor said.

Director Brig Gen Dr Zulfiquer Ahmed Amin did not tell the names of the companies that supplied the equipment.

He also did not say how much money was spent for buying these masks or how many have been bought.

"We have got some complaints from the doctors. We are investigating the allegations. We are now collecting masks from another source," he said.

He added that those who complained about the quality were asked to return the masks and were given new ones.

Doctors in many public hospitals expressed their anger when they were given fake masks and other protective equipment in early April.

Health care professionals in various hospitals raised questions about the quality of respirators, with some taking to social media to express their frustration. Prime Minister Sheikh Hasina also talked about the issue.

Counterfeit and low-quality masks pose potential health risks for the healthcare professionals and their families as well as the people who are treated by them, experts said.

At least 71 physicians have died with Covid-19 infection while 11 others passed away with what appeared to be the coronavirus, according to Bangladesh Doctors Foundation.

In the US, the Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health and the Occupational Safety and Health Administration regulate N95 respirators.

N95 means a respirator that blocks at least 95 percent of very small -- 0.3 micron -- airborne particles. A micron is one-millionth of a metre, and viruses are in the range of 0.3 microns.