Gas purity needed?

[bludmndalm]

Is there a specific purity needed for inert gas method? PPH 2022 said to make sure the purity testing had an oxygen rating of less than 2%, but the test with the mask said the oxygen level dropped to lower than 1%. What is the purity rating needed? Like what is the highest amount of oxygen that can be in the inert gas?

 

[ipmanwc0]

Not sure, but really pure nitrogen isn't that hard to obtain I got mine at 99.99