An Innovative Desk Push-Pull Device for Reducing Airborne Contaminant Exposure in Office Environments

Most human-centred ventilation devices aim to reduce cross-contamination by targeting the breathing zone, potentially causing contaminant accumulation and spread into the surrounding area. This study introduces a novel desk push-pull system (Desk_PPS) that aims to reduce contaminant transfer within the occupant microenvironment. The device employs two perforated plates on each side of the desk: one supplies clean air while the other extracts contaminated air, establishing a clean-air barrier that minimizes contaminant exchange between the occupant's microenvironment and surroundings. A computational fluid dynamics model was developed to predict contaminant spread, with the flow-inducing device model experimentally validated. A parametric analysis was conducted to optimize the Desk_PPS for face-to-face and side-to-side sitting configurations, focusing on operating flowrate and perforation diameter. Cross contamination was quantified using intake fraction (IF). The Desk_PPS substantially reduced exposure relative to the No Desk_PPS case. In the face-to-face setup, the lowest IF values occurred at 54 l/s: 2.56 × 10⁻⁴ and 2.41 × 10⁻⁴ for 5 mm and 10 mm perforations, corresponding to reductions of 60% and 62%, respectively. The 5 mm perforation generated a narrower, higher-momentum jet that better confined contaminants near the source and reduced downstream accumulation near the exhaust, whereas the 10 mm perforation produced a broader flow field creating a larger low-contaminant zone around the exposed occupant, particularly at 43–54 l/s. In the side-to-side configuration, IF fell from about 7.1 × 10⁻⁴ without Desk_PPS to 1.9 × 10⁻⁴ at 54 l/s for 5 mm diameter, a 73% reduction. Overall, Desk_PPS performance depends on the interaction between flowrate, perforation diameter, and room-scale contaminant transport.