Sikkim NHPC Teesta Stage VI collapse exposes unseen tunnel gasses

India Jul 21, 2026

The recent tunnel collapse at the under-construction NHPC Teesta Stage-VI hydropower project in Sikkim has shown how risky underground work can get.

Rescue teams found carbon monoxide inside and suspected methane too, both making it tough (and dangerous) to reach trapped workers.

Methane is especially tricky because you can't see or smell it, but if enough builds up, even a tiny spark could trigger an explosion.

Tunneling needs ventilation and monitoring

It's not just methane: gasses like hydrogen sulfide and carbon dioxide can also sneak into tunnels, causing breathing problems or worse.

That's why modern tunneling relies on constant air checks and strong ventilation to keep everyone safe.

For anyone working underground, keeping an eye on these invisible threats is a must.