title: Applying open-path FTIR with a bi-beam strategy to evaluate personal exposure in indoor environments: experimental results of a validation study.
abstract: 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.
authors.affiliation: Department of Environmental Health, University of Washington, Seattle, WA 98195, USA.
authors.forename: Chang-Fu
authors.initials: CF
authors.lastname: Wu
authors.forename: Michael G
authors.initials: MG
authors.lastname: Yost
authors.forename: Janice
authors.initials: J
authors.lastname: Varr
authors.forename: Ram A
authors.initials: RA
authors.lastname: Hashmonay
mesh_terms: D016902:Air Pollution, Indoor / Q000032:analysis*; D004784:Environmental Monitoring / Q000379:methods*; D006801:Humans; D008962:Models, Theoretical; D016273:Occupational Exposure; D016272:Occupational Health; D013048:Specimen Handling; D017550:Spectroscopy, Fourier Transform Infrared