Is mugwort heat therapy (moxibustion) good for respiratory health?

My friend was diagnosed with cancer and has been consistently visiting a traditional Korean medicine hospital, undergoing various types of heat therapies.

I went together to receive mugwort heat therapy because it's said to be good for immunity.

I placed mugwort on my stomach and lit it, and as my stomach warmed up, I started to feel sleepy and relaxed.

But I wondered if the smoke from the mugwort was okay for the respiratory system.

The doctor says that the smoke from mugwort heat therapy is okay, but I'm curious.