Suggestions on the Ventilation Design for an AIDS Laboratory in China

Abstract

In order to help in the prevention of the spread of AIDS in China, many biomedical laboratories have recently been constructed to perform tests for the HIV. For these con structions some engineers have simply followed the ventilation design requirements for clean rooms, al though putting more emphasis on the air cleanliness requirement of the laboratory. However, this approach has brought about higher construction and operating costs for the ventilation system and resulted in a poor hygienic safety factor. It was felt that better suggestions for the ventilation design were needed. Surveys on the ventilation in four AIDS/HIV laboratories were carried out, during which the air pressure of the laboratory, the air cleanliness, the air change rate and the airflow pat tern were tested. On the basis of these studies, and refer ring to the regulations for cleanrooms and biomedical laboratory design, several proposals were made. Firstly that negative pressure should be created by exhaust ventilation to guarantee inward airflow to the laboratory. Next that extreme air cleanliness is not required for the running of class II biosafety cabinets with air change rates in the range of 30-60 air changes per hour. Also, a rational directional airflow pattern should be created to guarantee both that clean air reaches the workers first and then flows to contaminated areas and that there will be no dead air spaces in the laboratory. Finally, the exhaust air from a level 3 biosafety laboratory should not be recirculated in order to give a greater biosafety factor under'class 10,000' air cleanliness regulations.