Wind effects on the pollutant containment zone in an asbestos removal worksite - field measurements

For any indoor pollutant removal worksite, such as in an asbestos containment zone, it is a mandatory requirement that the indoor pressure is kept lower than the outdoor pressure to ensure containment. For asbestos removal, this is commonly achieved by installing negative pressure units as a part of the on-site mechanical ventilation system which is designed to generate an internal-external pressure gradient of 10 Pa (instantaneous value as per the regulatory requirements in France). However, this magnitude of depressurisation might not prevail when taking into account ambient atmospheric wind conditions at the worksite. At worst, this can cause the momentarily breaching of the mechanically induced containment. For that reason, the present project is aimed at investigating the impact of atmospheric wind conditions on the performance of mechanical ventilation systems by predicting the internal-external pressure gradient.
As an initial stage of this project, this paper presents field measurements carried out at an active asbestos removal worksite (shown in Figure 1), located in Soulac-sur-Mer, France, equipped with working mechanical ventilation systems. Internal and external pressures as well as wind speeds and directions at multiple locations at the worksite are measured simultaneously by using differential pressure sensors and 3D ultrasonic anemometer in order to determine the relation between those parameters.