Measured influence of overhead HVAC on exposure to airborne contaminants from simulated speaking in a meeting and a classroom

This article was initially posted below

Indoor air. 03.09.2021 doi: 10.1111 / ina.12917. On the internet in advance of printing.

Abstract

Check gasoline experiments were being carried out in a 158 m3 area with overhead source diffusers to investigate the distribute of contaminants via simulated speech in spatially distant meeting and classroom configurations. The home was located in a 237 m3 cell with an open up plenum return to the HVAC procedure. Heated mannequins at the desks and a researcher operating the tracer release apparatus showed 8-9 warmth plumes. The experiments were carried out below conditions without having compelled air and neutral, cooled or heated air with 980-1100 cmh and without the need of / without the need of 20% outside the house air. CO2 was unveiled in just about every experiment on the head of a doll to decrease modest (<5 µm diameter) respiratory aerosols. The metric of exposure relative to perfectly mixed (ERM) is introduced to quantify impacts, based on measurements at manikin heads and at three heights in the center and corners of the room. Chilled or neutral supply air provided good mixing with ERMs close to one. Thermal stratification during heating produced higher ERMs at most manikins: 25% were ≥2.5 and the highest were >5 × properly blended situations. The operation of two air purifiers in the zone, which with each other moved 400 cmh vertically in the place, ensured enough mixing to mitigate enhanced exposure fluctuations.

PMID: 34477251 | DOI: 10.1111 / ina.12917