Controlling the ingress of particulate contamination into cleanrooms and other controlled environments is paramount in order to maintain the integrity of products and processess. Personnel traffic is the most important factor which must be controlled. Esco Pass Boxes and Transfer Hatches are a cost effective solution as they allow materials to be transferred into the controlled environment without actual personnel movement. They may also be used to protect the external environment from egress of contamination, for example, in biological safety laboratory applications.