JOHOR BARU, Aug 3 — A total of 24 pupils, two teachers and two canteen workers from the SK Sungai Tiram primary school in Ulu Tiram experienced nausea due to exposure to chemical fumes believed to be from industrial waste pollution of a nearby river over the past two days.

Johor Jaya fire station operations commander, Senior Fire Officer II Mohd Salleh Mohamed said 17 personnel with two fire engines and a specialist hazardous materials (hazmat) team from the Larkin fire station were sent to the school at about 3.13pm last Tuesday after a distress call about a foul chemical odour.

"Upon arrival, all pupils, teachers and other staff were instructed to leave the school’s compound immediately while firemen conducted aerial readings at the scene of the incident with personnel from the Johor Department of Environment (DoE),” he said in a statement today.

He said the hazmat team went to work using gas analysers at two sites, an illegal factory processing used palm oil, and an orchid farm, that returned normal readings at first.

He added that the team later detected methyl mercaptan fumes.

Methyl mercaptan, which is based on methanethiol, is a flammable and colourless gas with an unpleasant odour. It is used as a gas odourant; an intermediate in the production of pesticides, jet fuels and plastics; and in the synthesis of the amino acid methionine.

Mohd Salleh added that the detection process continued yesterday afternoon with additional equipment including long range detectors, gas analysers, radiation detectors and gas metres in several designated sectors.

"After making an assessment at the location of another factory area using the GT5000 gas analyser, there was increased reading of methyl mercaptan.

"Upon investigation, the Hazmat and DoE teams found that there was an activity of burning the intermediate bulk container (IBC) tank which contained waste materials in the form of sludge and liquid waste that also ran into the waterway of a nearby river,” he said.

Mohd Salleh said its findings will be handed over to the Johor DoE for further action.

"We are also grateful to the Health Ministry personnel who assisted in devising a plotting arrangement for residents who have symptoms.

"This helped us to determine the extent of a particular sector for detection,” he said.

There have been several complaints of foul chemical odours due to environmental pollution in Johor in the past few years with the most recent case just two month ago.On June 20, Johor Fire and Rescue Department deployed its Hazmat team after detecting fumes from chemical contamination originating from industrial waste at Kawasan Perindustrian Maju Jaya in Kempas here.

The hazardous materials found were listed as acrolein, benzene, carbon dioxide, methane and ethylene oxide.

In September 2021, more than 30 residents from Kampung Baru Sri Aman in Seelong near Kempas were evacuated after two residents fell unconscious from inhaling pungent chemical fumes from a nearby river.

The cause of the fumes was later linked to petro-chemical waste that was dumped upstream.

Prior to that, Johor was hit by the Sungai Kim Kim toxic fumes in 2019, which has been described as one of the worst air pollution in the country’s history.

More than a thousand residents, many of them schoolchildren, in Pasir Gudang were directly affected after chemical waste dumped into Sungai Kim Kim released toxic fumes into the air on March 7.