A particularly gruesome affair, that. Relevant episodes of Well There’s Your Problem: Part 1 & Part 2

the big killer from the 1984 disaster is long gone by now, because it was a gas that additionally reacts with water. it’s probably everything else that was there that they’re disposing of by burning (like naphthol, the other compound used in carbaryl synthesis that was taking place there). then there are heavy metals if any that won’t be disposed of this way

modern engineering practices make accident of this type much less impactful and less likely (reactive intermediates like methyl isocyanate or phosgene are only made on demand, continuously and consumed immediately)