On Apr. 27, passengers scrambled to purchase masks in drugstores at Narita International Airport in Japan's Chiba Prefecture in the face of reports of swine flu infection in Mexico, the United States and Canada.

A drugstore manager said sales of the masks are about 30% higher than usual and that stocks are running out for a particular type of mask which is believed not to allow the virus to pass through it.

"Since around Apr. 26, the number of those who are buying masks due to concerns over swine flu has increased," the manager said.

A 50-year-old woman from the city of Saitama heading to Switzerland bought six masks and said, "I rushed to purchase these masks just before departure as the infection seems to be spreading worldwide."

Photograph: A woman looks at masks in a drugstore at Japan's Narita airport.