Worn to prevent the spread of the deadly coronavirus, face masks that were discarded and now litter the streets pose a potential public health hazard to others.

A health expert said viruses and germs may be attached to the disposed masks.

“Those who pick up such masks are at risk of infection,” said Yoshihiro Yamamoto, a professor at Toyama University Hospital specializing in preventing infectious diseases. “There is also a danger of infection by those who mistakenly come in contact with face masks blown by the wind.”

A growing number of cases of used masks littering sidewalks, train stations and parks are reported as drug stores and other retail outlets continue to experience major shortages.

In the first half of April, discarded face masks could be seen scattered about in Tokyo. They were on the sidewalk by a major supermarket, by an elevator in a commercial facility, hidden among plants by a sidewalk, next to public toilets as well as in front of a JR train station.

Pedestrians at the train station walked while keeping a wary eye out to avoid the discarded masks.

Pirika Inc., a Shibuya Ward-based environmental start-up, has developed a smartphone app that shows areas where litter is prevalent.

Company officials said posts about discarded face masks have increased since February when concerns about the rising number of coronavirus infections heightened.

In February, there were 168 reports about discarded face masks, a 5.6-fold increase over February 2019, while there were 176 reports in March, a 6.8-fold year-on-year increase.

“I believe the increase in the ratio of face masks among total litter is a reflection of the times,” said Fujio Kojima, 33, Pirika’s CEO.

One post to the company’s website on Feb. 17 said, “It is very regrettable that there are so many people who are discarding the face masks as trash” at a time when people are more concerned about infections.

Another post reported finding cigarette butts and a face mask in an empty can, while another said it was disheartening to find so many discarded face masks when many people could not get their hands on one.

Yamamoto recommended against picking up such face masks and urged that phone calls be placed with local governments to have a specialized agency collect the litter.

According to officials of the Taito ward government, which has jurisdiction over the major tourist spot of Asakusa, calls about discarded face masks will lead to staff collecting the litter using tongs while wearing protective gear, goggles, face masks and gloves. While that is standard procedure for handling unsanitary garbage, special care is taken for face masks, the officials said.

But when an individual has to collect discarded face masks, Yamamoto recommended wearing masks and rubber gloves. He suggested placing the collected face mask in a plastic bag, binding the bag and placing it in a covered garbage can that has another larger plastic bag inside.

The double coverage would reduce the risk of garbage collectors becoming infected, Yamamoto said.

The Environment Ministry has also created a flier for household use regarding the proper method for discarding of face masks.

Ministry officials said proper disposal would prevent infections within the household, but also among local government officials and waste processing company employees who will have to handle the garbage.