Japanese coronavirus guidelines encourage people to wear masks, but medical professionals have warned parents not to put them on infants as it is difficult to notice changes in face color, expression, and breathing , he said in a brochure.
"It is possible that masks will prevent infants from breathing and increase the risk of heat stroke," reads the brochure.
Infants have narrower airways and masks can make breathing more difficult, increasing the load on their lungs, he continues.
There is also an increased risk of choking, especially if small children vomit behind a mask.
Infants have a relatively low risk of coronavirus infections and the association concludes that masks are not necessary for infants under two years of age.
On Monday, Japanese Prime Minister Shinzo Abe lifted the state of emergency nationwide. He had been in place for almost a month, but authorities lifted him a week earlier than expected.
However, Abe on Wednesday extended a travel ban to 111 countries, including the United States, India and South Africa.
The list of prohibitions has been extended this week by 11 countries and prohibits foreign nationals who have stayed in these countries from entering Japan.
Japanese citizens are still allowed to enter the country, although they will have to undergo medical tests and self-quarantine for 14 days.
