What I want to protect from is sensitization and decrease risk known or unknown. You can vent outside without suffocating. I vent outside. My shop is 30 X 50 and I built it considering venting outside. I put gable vent panels the full length and up the peaks. I did not use a ridge vent. I have 12' walls and installed a drop ceiling. The gable vents are above the drop ceiling, but there are ample openings for air movement in the ceiling. When the D.C. Is running the makeup air is drawn through the gable vents and mixed with air above the drop ceiling before drawn into the shop below. I don't AC the shop and this wouldn't be ideal for a AC shop. Since the air above the drop ceiling is heated air that has risen, I can run the DC for hours with very little decrease in temperature. This works for a shop my size, but may not be near as effective for a smaller shop.
When working I had more money than time. In retirement I have more time than money. Love the time, miss the money.