Due to the variance in airflow between rooms and the stringent requirements to satisfy the CSA and ASHRAE (Hospital construction standards) for a negative pressure operating environment, simply buying a HEPA filter does not meet any established standard. As a dental professional, your expertise is in the diagnosis and treatment of diseases of the oral facial complex. In HVAC construction and design, leave it to the experts who has proven expertise so that you, your staff and your patients can have peace of mind.