Scuba tanks - surface air or otherwise, need a high pressure and they need filtered systems better than found on commercial plant.
The air is not Dry - but a lot of the moisture is removed. Humans are generally breathing this and need some moisture otherwise the throat would dry and they would dehydrate. Even snorkelling leaves your throat bone dry and that's normal air with water evaporating all around.
This is specialist kit needing regular servicing and probably engineer inspection to comply with safety and legislation/insurance conditions.
In the same way I would never use a stirrup pump to fill my gun, I would not use anything other than a proper dive compressor to fill my tanks
In a battle of wits I refuse to engage with an unarmed person.
To one shot one kill, you need to seek the S. Kill only comes from Skill