Relationships of vapour pressure deficit on aerosol particles and airborne bacteria in dairy barns

In recent decades, vapour pressure deficit (VPD) has been a critical driver of terrestrial ecosystems. An investigation was conducted in finding out the influence of VPD on various sizes of aerosols (aerosol particles or particulate matter) and different types of airborne bacteria in different types of dairy barns in Tochigi, Japan. The highest VPD, 715.34, 599.78, and 733.03 Pa (Pascals) were observed in a naturally ventilated tie-stall dairy barn, open type dairy barn, and a dairy calf barn, respectively during the warmer months of the year. But the lowest VPD, 322.34 Pa observed in a mechanically ventilated enclosed type dairy barn during the warmest month (August) of the year. A strong positive relationship (R = 0.86, p = 0.03) was observed between 5.0 and 10.0 mm aerosol particles and VPD in the enclosed type dairy barn during the summer. A comparative strong positive relationship (R = 0.59, p = 0.01) was observed between airborne total aerobic bacteria and VPD in a tiestall dairy barn during the warmer months of the year. These findings will be crucial in minimising abundance of aerosol particles and airborne bacteria from different types of dairy barns by regulating VPD. Furthermore, the impact of VPD on aerosol numbers and airborne bacteria in dairy barns should be considered in a broader context in reducing particulate pollution and airborne bacteria in various microenvironments in the era of future global warming & climate change. (c) 2023 IAgrE. Published by Elsevier Ltd. All rights reserved.