Due to allergies I built a cab that is fairly air tight and makeup air is filtered,it works quite well and I don't have to wear that mask. The frame is thin wall 1inch square tubing and plexiglass and plywood make up the rest. Insulated with fiber board,carpet and spray foam. I have 3 good sized 12 volt thermo units on top with a fan cooling those and fans on the inside and a makeup air fan that pulls outside air through the air cleaner. An auto alternator provides power for the units. The large heatsinks are diodes to keep the 12 volt as a clean signal but the thermal units gradually stop working and after 2 years they get cool enough to collect moisture but that is about all, they are not worth the cost which is a fair amount.
I am gathering parts to put in freon unit but not till winter, with all this rain I have to mow every 4 days.