I don't know and neither do I care. I know it is not as good as being able to freely breathe. Why in the world would you want to know? O_o
I never got that in my chest really, just pain in my neck, and my eyes hurt like the ba<x>ses wanted to pop and I was getting sleepy, then after I had one of the most horrid headaches one could have, and my neck was bruised bad for over a week.
I would ask my grandmother but she died from it.