JOHOR BAHRU, September 4 - The Johor Department of Environment (DoE) confirmed the cause of odor pollution in several areas of Johor Bahru yesterday was due to high concentration of ammonia gas.

Johor DoE Senior Deputy Director, Mohd Rashdan Topa said air quality monitoring carried out in Sungai Pandan at 4pm yesterday showed readings above the normal level of AEGL-1, which is the safe air concentration level.

However, the second test at the same location, at 1.10 this morning showed that the reading was back to normal.

"So far we can't be sure, but based on yesterday's high measurement, it is ammonia gas that other parameters cannot detect. Ammonia gas was above the normal level," he said.

He said this after conducting a survey in Sungai Pandan, here today.

Rashdan said that his team was still investigating whether the gas was released from a nearby premises or dumped by an irresponsible party.

The DoE is also waiting for the results of the water and soil samples that were sent to the Chemistry Department yesterday.

So far, two members of the public have sought outpatient treatment after showing symptoms of vomiting and nausea as a result of inhaling the gas.

Meanwhile, a survey in Kampung Melayu Pandan found that the situation is improving compared to yesterday.

"Today I noticed that how much different it was this morning. I mean yesterday, the situation was really bad. Today, it seems that there is still a little smell, but the condition of the river has recovered. The colour of the river has also started to change, but the smell is from the waste. The remains that stick to the banks of the river are the only ones left," said Chairman of the Kampung Melayu Pandan's Residents Association, Mohd Faudzi Mohamad.

"For your information, all nursery schools are closed for today but will resume operation tomorrow because today we are still taking precautions," said a nursery teacher, Siti Noor Azliza Abd Aziz.