Nearly 500 schools and kindergartens in Malaysia have been ordered to close until Thursday after many students complained of breathing difficulties and vomiting.
It's the second such incident this year, where students have been hospitalised with symptoms suggesting they breathed toxic fumes, possibly from waste dumped by factories.
Prime Minister Mahathir Mohamad has vowed to take tough action against those responsible for it.
"It seems like there are factories that are not very concerned about safety and thus, causing the incident to recur," he said. "That is why we have to identify those responsible for causing the pollution and take stern action."
Jordan tightens security after deadly church attack kills eight
France's luxury stores board up windows ahead of fresh protests
North Korea's Kim Jong Un visits China via Dandong bridge, South Korea source says
Typhoon Champi sweeps past Taiwan, leaving 1 dead, 500 injured
France boosts police presence, hoping to prevent repeat of riots
