National COVID-19 task force spokesperson Wiku Adisasmito said “scuba” masks and scarves were often made using only one layer of fabric, making it less effective in filtering respiratory and saliva droplets that carry the SARS-CoV-2 virus.

He went on to say that neoprene masks could slip under the nose more easily than any other types of mask.

“A good cloth mask is made of triple-layered cotton because of its ability to filter the virus particles. The more layers the masks have, the better the ability to filter such particles,” Wiku said during a press briefing on Tuesday.

He reminded the public to use face masks properly in public places. The mask should cover the entire nose, mouth and chin for better effectiveness in preventing virus transmission, Wiku added.

Read also: Masks reduce infection risk, likely preventing thousands of COVID-19 cases: Study

PT Kereta Commuter Indonesia (KCI), the operator of Greater Jakarta commuter line, recently advised passengers against using the “scuba” mask and scarfs upon riding the train.

“[The masks] are only 5 percent effective in preventing the risk of exposure to dust, viruses and bacteria,” the company posted on its official Twitter handle, @CommuterLine, on Wednesday.

https://twitter.com/CommuterLine/status/1306049737146073088

Citing Indian pharmaceutical company Varsoy Health Care and the Indonesian national COVID-19 task force, the train operator advised passengers to use N95 masks that had an 95 to 100 percent effectivity rate in filtering dust, viruses and bacteria; followed by surgical masks with 90-95 percent and cloth masks with 50-70 percent.

KCI had limited the number of commuter line passengers to 74 per car – 45 percent the usual capacity. The operator also enforced measures to reduce lines and crowds at stations.

The company also reduced train operational hours to 4 a.m. to 9 p.m. It also only allows passengers aged 60 and above to ride trains between 10 a.m. and 2 p.m.