I don't know what the author did but I suppose you would need to temper it somehow. I guess if you were to build it you could vent it inside if you prefer.
Thank you. Wow. That's alot of technology packed into that article.I just spray outside.
Only negative is a delay when it rains or being brave when it is cold.
The requirements for a PROPER balanced air draft spray booth and the conditioning of the replacement air is simply not in my budget, see link below.