The Aga Khan University Hospital has issued a ban on the use of a mask with valves. 

According to the institution, such masks will no longer be worn at its premises since they do not offer full Covid-19 protection. 

In a statement, masks with valves only protect the wearer but not those around them. 

“The design of these masks allows inhaled air to be filtered, but the exhaled air is not. The exhaled air can be expelled towards others even more than from a person not wearing a mask,” AKUH said.

COVID-19 spreads mainly through respiratory droplets when a person talks, sneezes, sings, or coughs. Masks can help stop those respiratory droplets.

The ban by AKUH comes as the World Health Organization (WHO) issued an advisory against the use of masks with exhalation valves.

AKUH notes that masks with valves are intended for industrial workers to prevent dust and particles from being breathed in as the valve closes on inhale.

However, the valve opens on exhale, making it easier to breathe and allowing any virus to pass through the valve opening.

“This makes the mask ineffective at preventing the spread of COVID-19 or any other respiratory virus,” a statement on the WHO website reads.

According to experts, the one-way valves may provide the wearer more comfort since the valves allow air to escape from the mask and keep people more relaxed, but the valves also will enable the virus to run from the mask.