TOKYO -- An increase in people seen drinking on downtown streets in Japan, apparently because bars have shortened their business hours in some prefectures under the third state of emergency over the coronavirus, has prompted experts to warn about the risk of infections.
Analysis by the Riken science research institution and other groups has revealed that people speaking loudly without masks shower infectious airborne droplets on others even when outdoors.
On the night of April 23 -- the day the Japanese government decided to declare the third state of emergency for Tokyo and some other prefectures -- people seeking places to drink crowded around JR Koenji Station in the capital's Suginami Ward after 8 p.m., the time the metropolitan government has requested bars to close by. People were seen partying while drinking cans of beer and shochu liquor they brought as they sat closely to each other on benches and other places. They were speaking while their masks hung beneath their mouths apparently so they could easily drink.
"As there are way more people than I thought, I'm worried about infections," said a male corporate employee in his 20s who was with some other people. He added, "But we have no choice but to drink outside because bars are closed."
Similar scenes were also seen in front of JR Takadanobaba Station the previous night. Five male university students in their 20s were enjoying a conversation with canned beers and shochu alcoholic drinks in their hands. One of them who said he was looking for fulltime work commented, "I can't help but meet friends due to job-hunting stress. The risk is low outdoors where air is ventilated unlike indoors. There is also a sense of openness." Another group were eating hamburgers as they sat in a circle about 1-meter in diameter.
Although many people think it's fine to drink outside, there is an infection risk if they speak without masks even outdoors. A research team comprising members of Riken and other groups simulated a situation on the supercomputer "Fugaku" where people were speaking loudly while eating and drinking around an outdoor table for 30 seconds.
In the simulation with no wind, 10% of airborne droplets ejected by one person reached another person facing 1 meter across, and two people on both sides of the latter person were also showered with droplets. When the distance was 1.7 meters, the amount of precipitation was half that over 1 meter. Droplets spread when the wind blew, and in a situation where wind direction frequently changed, droplets reached everyone around the table.
Makoto Tsubokura, the Riken team leader and a professor at Kobe University, said, "Regardless of whether people are indoors or outdoors, measures such as wearing masks can reduce airborne droplets by a large amount, and can significantly reduce the risk to surrounding people."
The central government has asked restaurants serving alcohol to temporarily close in four prefectures -- Tokyo, Osaka, Kyoto and Hyogo -- which are under the state of emergency. The quasi-emergency measures will also be implemented in seven prefectures -- Miyagi, Saitama, Chiba, Kanagawa, Aichi, Ehime and Okinawa. As a result, it is feared that an increasing number of people will drink alcohol and eat snacks, which they buy at supermarkets and convenience stores, on the streets.
Kazunori Oishi, head of the Toyama Institute of Health and an expert on infectious diseases, commented, "As infections did not stop spreading under the quasi-emergency measures, even stronger steps must be taken." He also added: "Some people who are infected with the coronavirus are asymptomatic. Considering the current situation in which community-acquired infections have spread, it's best to think that infected people are nearby. The infection risk is high when speaking with people closely without masks even outdoors. I would like people to stop drinking on the street, abandoning their optimistic ideas."
(Japanese original by Yuki Nakagawa and Takashi Kokaji, Lifestyle and Medical News Department)