How to achieve negative pressure flow
Dual extractor fans pull air into the lab, and out through advanced filters. These fans power the airflow from your cabinets, and also ensure that even if an organism does escape your work space, the flow of air will pull it away from the entrance and through the filters.
The vents are positioned on the far side of the room to ensure the least possible chance that you can become infected in the event of a spill.
The dual fans both run at 50% power, meaning even if one has a mechanical failure, the lab will still remain safe.
Remember the basic! Check this out: Negative pressure