
Dr Chanthana Phadungtos from the Bureau of Occupational and Environ-mental Diseases said combining the two chemicals created sulphur dioxide, which caused skin and conjunctival irritation. Mixed with water, it creates a mild sulphuric acid, slightly more intense than vinegar. People exposed to it could feel itchiness and burning sensations. It was not a liquid form of tear gas and wasn’t a chemical weapon.
It was allowed for use under a riot control law. However, as this combined substance yields an acid, it could harm people who touch it, if it was mixed too intensely, she said.
Dr Chanthana said protesters could do a litmus test – and if paper turned orange or red, it meant the level of acidity was very intense. The combination of water and these substances should not be too strong or it would be harmful if sprayed on protesters. She urged protesters to quickly wash any exposed skin with clean water immediately to reduce irritation.