Echo the above: an air curtain combined with a rapid open/close door can be defended. I helped document this at a site where a storage building was across a parking lot from the production building. They used an outdoor forklift to pickup pallets of goods at storage, drive across, and drop it just inside the door of the production building. Hitting the open button activated the air curtain first, then quickly opened the door, then the door closed before the curtains turned off. One auditor was very interested to observe the devices worked in that exact order.
We defended this practice using EMP, including air plates specifically added to those doors to help show the blowing air curtains were not introducing a higher level of contaminates compared to the rest of the site. We had our PCO write up a specific statement to address how/why traps were laid out near these doors, and made sure there were ILT's specifically on either side of the door (but placed sufficiently far to avoid attracting outside flies if doors had to be opened at night). They included in their statement there is a ramp up to the door, making it unlikely that a rodent would want to go around and climb the ramp being exposed to predators.
Don't get me wrong, the auditors always gave that setup an extra level of scrutiny. They'd rather see a dock door sealed to a trailer for all loading/unloading, but you can reason with them that you're doing your best to control a situation that's not ideal.
