Laboratory Air Changes: What is all the Hot Air about?

Room air changes per hour (ACH) is very likely not the main parameter in determining good air quality and health and safety in the laboratory. Protecting the health and safety of laboratory personnel is the prime objective of laboratory ventilation. Energy conservation is a secondary objective. It is not important what the air exchange rate is in a laboratory provided the space and building are designed to control hazardous emissions at the source of the generation and future changes in activities are tightly controlled.The lack of exposure assessment studies in laboratories related to air exchange rates and health effects makes it difficult if not impossible to select an air exchange rate that is protective of health. This reality in large part contributes to EHS professional's [DiBerardinis, L., et al. Guidelines for Laboratory Design: Health and Safety Considerations; John Wiley and Sons: New York, NY, 2003] reluctance to lower air exchange rates for energy conservation purposes since they are unsure of the effect on health and safety and their ability to control or even be aware of future changes in activities in the laboratory.This paper describes some of the factors that affect air exchange rates in laboratory design and presents a decision logic for determining acceptable air exchange rates based on the proper design of the laboratory for controlling airborne emissions.