Rich Grise wrote:

Pete C. wrote:

This a a notable risk, particularly if you plan to be breathing this
pure O2 in proximity to a running engine. A safer option would be to
breath air from your compressor via a proper filter. Such filters are
available commercially to provide breathing air from shop air. I expect
Iggy can find one used for $25.

Or you could probably get an aquarium pump for about ten bucks. ;-)

Cheers!
Rich

An aquarium pump isn't likely to supply sufficient volume.