Air distribution may rely on unidirectional flow for high-grade cleanrooms, while mixed-flow patterns suit general areas. HVAC design for cleanrooms & laboratories aim to sweep airborne particles toward return ducts without disturb product or operator activity. Careful velocity control keeps laminarity intact where needed. https://adrotixengineering.wixsite.com/adroitix/post/ensuring-product-purity-with-hvac-design-for-pharmaceutical-manufacturing