Johor Fire and Rescue Department has identified 15 types of chemicals in air samples taken from areas surrounding Sungai Kim Kim, including hydrogen cyanide.
Its director Datuk Yahaya Madis said while most of these gases were harmless, some – such as hydrogen cyanide – could be harmful if found in high concentration or if a person was exposed to it for too long.
He said currently, based on their tests, the concentration of hydrogen cyanide was at a safe level of 3ppm.
