Applying open-path FTIR with a bi-beam strategy to evaluate personal exposure in indoor environments: experimental results of a validation study.
Wu-CF; Yost-MG; Varr-J; Hashmonay-RA
Am Ind Hyg Assoc J 2003 Mar/Apr; 64(2):181-188
This study evaluated the performance and feasibility of using open-path Fourier transform infrared (OP-FTIR) with a bi-beam strategy to assess personal exposures in workplaces. The bi-beam strategy combines a long beam and a short beam measurement to calculate the average concentration level of the segmented region. A series of experiments was conducted with six human subjects at two workstations inside a chamber. A bi-beam geometry was set up for each workstation. Each subject repeatedly performed two tasks (9 min/task), which were designed to simulate a painting and an assembly task. For each task a tracer gas (N(2)O) was released from a point source near the subject. During each task, while the OP-FTIR collected the N(2)O spectrum, bag samples were collected simultaneously at nose and lapel height. Statistical data analysis applied a general linear model with the bag samples as the dependent variable. Results show that the locations, tasks, and subjects are not significant factors when using OP-FTIR measurements with the bi-beam strategy to estimate personal exposure at the nose height. The model used in this study fits the data reasonably well (R(2)=0.87), and when it is compared with a second set of experimental data, the bias is 0.7 ppm (3%) and the precision is 5.5 ppm. This study demonstrates that the bi-beam sampling strategy may offer a new approach for applying OP-FTIR to industrial hygiene monitoring.
Environmental-health-monitoring; Humans; Models; Occupational-exposure; Occupational-health; Simulation-methods; Statistical-analysis;
Author Keywords: beam geometry; gamma model; open-path FTIR; personal exposure
Department of Environmental Health, University of Washington, Seattle, WA 98195, USA
American Industrial Hygiene Association Journal