Five people were hospitalised after a man accidentally discharged an anti-bear spray inside a post office in the central Japanese city of Nagoya on Wednesday.
The incident has drawn attention to the growing presence of bear deterrent products across the country amid a surge in fatal attacks.
Huynh Nhat Duy, a 22-year-old Vietnamese national, was arrested on Thursday on suspicion of obstruction of business after the spray went off inside the city-centre post office.
He apologised and told the police the discharge was unintentional, AFP reported.
“Eight people felt sick, and of those five were sent to the hospital. But there was no report of serious injuries or illness,” fire department official Ryohei Asano said on Wednesday, according to Japan Times.
Anti-bear sprays, sold in outdoor activity stores across Japan, contain capsaicin, the chemical compound found in chilli peppers, which causes a burning and irritating sensation on contact. Authorities recommend people carry them when venturing into the mountains, which make up around 80 per cent of Japan's land area.
The incident comes as Japan records an unprecedented rise in bear attacks. At least five people have been killed since 1 April, all in the northern Tohoku region, following a record 13 deaths in the last fiscal year.
This year is the first since records began in 2017 to see more than two deaths in the April to June quarter alone. Authorities are also investigating a possible sixth fatality after a man's body with bite marks was found in a mountainous area in Tohoku this week.
Scientists attribute the rise to an increase in the bear population, a decline in the number of people living in rural areas and variations in the availability of the animals' usual food sources. There has also been a sharp jump in sightings since bears emerged from hibernation this spring, with the animals increasingly venturing into towns and cities.
In response, Japan has begun installing more than 800 cameras in its northern mountains as part of a nationwide population survey, initially targeting six major bear populations in Tohoku before expanding across the country over the next four years.
Jars of honey mixed with wine, placed at roughly human-head height, are used to attract bears, whose unique white chest markings are then photographed as they stand on their hind legs to sniff the bait, according to Japan Times.
Bears are also increasingly venturing into urban areas. In June, dozens of police officers, hunters and city officials spent four days trapping a bear roaming the city of Utsunomiya, north of Tokyo, forcing mass school closures.
Last week, authorities in Hachioji on the outskirts of Tokyo announced plans to purchase 700 anti-bear sprays for schools and community organisations, along with portable electric fences and devices that emit high-pitched sounds to deter the animals.
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