When gas began leaking from a nearby chemical factory and drifting towards his house in southern India, there were no warnings and no alarms, welder Elamanchili Venkatesh said.

He realised something was wrong when he woke up choking and spluttering in the pre-dawn darkness on Thursday in RR Venkatapuram village, just 250 metres from the plant owned by South Korea’s LG Chem Ltd.