I don’t think you will suffocate by covering your face with a blanket. To answer the rest of your questions, it’s fairly simple. The blanket is not an impermeable material to block all the CO2 that you exhale.
If so how fast? What does the disperse rate depend on?
It’s a cloth and obviously, the CO2 will disperse at a slower rate, but not at the slowest to suffocate you. However, this depends on the type of sheets you are using. If you use a very thick woolen sheet, you might actually suffocate yourself (Your brain will wake you up anyway!).
Source – I bury my head inside my pillow every night. :)
