Lab doggy door

Hey everybody I’m putting the finishing details on my new lab and my question is about the exhaust/air exit, my lab is 5’ wide 10’ long and 7’ tall, I have a 3’ x 4’ myers flowhood 1,000 cfm along the 5’ side that is backed into a prefilter room, so the flowhood is positively pressurizing, my question is where is best to put the doggy door exhaust hole, and how big to make it, here’s a pic for help I’m wondering back wall or side wall near the back corner and size 🙏

Isopropyl fumes are killing me I moved to a small lab 7’x9’ and it’s just recirculating air with a 3’x 4’ flowhood from myers mushrooms, I spray a lot of 70% iso and these last few weeks my throat and lungs are sore and irritated, I’m thinking to try to positive pressurize the lab by putting a hole in the wall and backing the prefilter from the flowhood thru it(maybe a grow tent on the prefilter side to create a “pre conditioning room” and run an air purifier in there too)and cutting a small doggy door hole low in the opposite corner in the lab to let air out, do you think that will get the iso fumes out of there? Until I do that I’m getting a respirator with organic vapor cartridges cuz it’s really hurting, any advice would be much appreciated 🙏