Survey Report: Evaluation of an Air Shower for Reducing Exposure to Carbon Monoxide at United States Port of Entry, Calexico, California

摘要

From July through December 2002, an engineering control evaluation was conducted to assess the effectiveness of a redesigned external air supply installed in two lanes at the Calexico West Port of Entry. Air diffusers, known as air showers, delivered roof top air to primary inspection lanes 5 and 7 at a height of 10 feet above ground. This improved delivery system was expected to provide cleaner, roof top air closer to the inspectors breathing zone resulting in reduced exposure to carbon monoxide. In the initial in-depth survey, carbon monoxide (CO) concentrations measured on the inspectors and in the lane area for those lanes outfitted with the air shower (primary lanes 5 and 7) were compared to those with existing ventilation (primary inspection lanes 4, 6, and 8). Following the initial survey, fixed area CO monitors were installed in primary inspection lanes 4 through 8 to provide long term measurement of area CO concentrations. The long term data was collected over several months to assess seasonal environmental variations and the effect of variable traffic flow among the primary inspection lanes. The results of the in-depth and long-term surveys showed that the air showers, as installed, did not result in lower personal or area CO concentrations.