Assuming this refers to a standard 200 litre capacity drum transported in the cargo tray of a standard pickup truck.
Even Thai law requires that hazardous liquids transported by road must be clearly labelled with the appropriate International hazard code for the cargo. This enables emergency responders to identify the cargo and react accordingly.
Looking at the OP pictures of venting vapour, anyone within a 100 metre radius not wearing a respirator could be at risk.
But let's just stand around and watch phones on video. 🙄