Assessment of terpene levels and workers' exposure in sawmills with Long Path FTIR

This study focuses on the assessment of airbone terpene levels in the saw shed of a sawmill. It describes results and practical aspects concerning the indoor use of a Long Path FTIR measurement technique that was primarily developed for emission monitoring in outdoor applications. The results from FTIR sampling are compared with results from personal adsorbent samples and a point monitoring PID instrument. The Long Path FTIR light path covered the entire length of the saw shed in the mill. This enabled measurement of real-time, path integrated concentrations along the beam path. The four monoterpenes alpha-pinene, beta-pinene, delta 3-carene, and limonene were identified along with ethanol. Quantification was achieved by using a classical least square evaluation software. The limit of detection of the individual terpenes was 1.5 mg/m3, or 0.27 ppm. The terpene levels in the sawmill fluctuated significantly and the average concentrations exceeded the Swedish 8-hour PEL (150 mg/m3, 25 ppm). Peak levels were recorded near the Swedish short-term exposure limit (300 mg/m3, 50 ppm). Results from simultaneous sampling with personal adsorbents, analyzed by GC, showed good agreement with the long path FTIR sampling (r = 0.98, n = 7). The FTIR application described is general in nature and offers a stable and convenient form for continuous monitoring over extended periods of times, and the conclusions drawn from this study may well be applied in other similar surveys.