The effect of the body wake and operator motion on the containment of nanometer-scale airborne substances using a conventional fume hood and specially designed enclosing hood: a comparison using computational fluid dynamics

Airborne substances in the nanoparticle size range would mostly follow the primary airflow patterns, which emphasizes the importance of understanding the airflow dynamics to effectively control exposures to toxic airborne substances such as nanometer-sized particles. Chemical fume hoods are being utilized as primary controls for worker exposure to airborne substances including nanometer-scale materials due to their overall availability and history of effective contaminant. This study evaluates the impact of the body wake on the containment performance of a conventional constant air volume (CAV) and a new “nano” ventilated enclosing hood using numerical methods. Numerical studies have been performed to predict leaks of nanomaterials handled inside the hood. We further performed experiments in this study to validate the velocity fields predicted by the computational fluid dynamic (CFD) models and to provide a basis for evaluating the impact of the human body on fume hood containment performance. Using these validated models, the effects of the motion of the arms moving out of the hood were simulated using CFD to assess how one of the common actions of an operator/user may affect containment. Results of our simulations show that areas near the hood side airfoils and directly behind the sash are more likely to concentrate contaminants released inside the hood and potentially result in leakage based on internal airflow patterns. These areas are key to monitor when assessing fume hood containment along with the operator/mannequin breathing zone to get an understanding of potential leak areas which might contribute to operator exposure as well as exposure to others inside the laboratory.