Carrying the concept of trust another step, how often do we check the air sample reports on the dive shop or charter boats compressor? I am less concerned over the oxygen level in Nitrox than the Carbon Monoxide and hydrocarbon levels, Nitrox or air. That was something we only worried about on air dives offshore (LP air compressors, often Diesel powered) since mixed gasses were all cryogenically purified. I have seen compressor air intakes at dive shops way too close to parking spaces. Sure enough, people would back in close to the compressor, let their engine run, and pick up/drop off bottles.
Look at the faith many people put in their LDS to service their regulators
using the same bench they repair outboards on. Interesting and thought-provoking topic
but it is making me worry about the breaks on my van.