Performance evaluation and improvement of local exhaust systems in a pharmaceutical workshop

In pharmaceutical workshops, harmful pollutants produced during the production process could be dispersed in the indoor environment. The emission of those pollutants is an important factor threatening the health of workers and of other occupants. In this paper, we studied pollutant emission characteristics to evaluate the quality of indoor air (IAQ) in one pharmaceutical workshop. It would release a large amount of particulate pollutants during the opening process of the centrifugal equipment because of the existing external suction hood ventilation system in the workshop during the production of the magnesium isoglycyrrhizinate injection material. We found that the particle size distribution had a peak for particles with optical particle size between 0.3 µm and 1 μm. The measured data also shows that the centrifugal equipment also released a large amount of volatile organic compounds (VOCs). To reduce the exposure concentration for workers, we propose an improved ventilation strategy, with an annular air curtain near the centrifugal equipment to create a pull-push ventilation strategy. We performed a three-dimensional numerical simulation of the flow field and of the pollutant concentration in transient conditions. We found an increased exhaust performance with the improved ventilation strategy, compared with the exhaust hood only. In fact, the capture efficiency of particulate pollutants increased by installing the annular air curtain.