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- Svedberg, U.R.A., et al.
(författare)
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Emission of Hexanal and Carbon Monoxide from Storage of Wood Pellets
- 2004
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Ingår i: Annals of Occupational Hygiene. - : Oxford University Press (OUP). - 0003-4878 .- 1475-3162. ; 48:4, s. 339-349
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: The objective of the present study was to investigate and describe the emissions of volatile compounds, particularly hexanal and carbon monoxide, from large- and small-scale storage of wood pellets. Methods: Air sampling was performed with Fourier transform infrared spectroscopy and adsorbent sampling in pellet warehouses, domestic storage rooms, lumber kiln dryers and experimental set-ups. Literature studies were included to describe the formation of hexanal and carbon monoxide and the toxicology of hexanal. Results: A geometric mean aldehyde level of 111 ± 32 mg/m3 was found in one warehouse, with a peak reading of 156 mg/m3. A maximum aldehyde reading of 457 mg/m3 was recorded at the surface of a pellet pile. Hexanal (70-80% w/w) and pentanal (10-15% w/w) dominated, but acetone (83 ± 24 mg/m3), methanol (18 ± 7 mg/m3) and carbon monoxide (56 ± 4 mg/m3) were also found. The emissions in a domestic storage room varied with the ambient temperature and peaked after 2 months storage in the midst of the warm season. Aldehyde levels of 98 ± 4 mg/m3 and carbon monoxide levels of 123 ± 10 mg/m 3 were recorded inside such storage rooms. Elevated levels of hexanal (0.084 mg/m3) were recorded inside domestic housing and 6 mg/m 3 in a room adjacent to a poorly sealed storage area. Experimental laboratory studies confirmed the findings of the field studies. A field study of the emissions from industrial lumber drying also showed the formation of aldehydes and carbon monoxide. Conclusions: High levels of hexanal and carbon monoxide were strongly associated with storage of wood pellets and may constitute an occupational and domestic health hazard. The results from lumber drying show that the emissions of hexanal and carbon monoxide are not limited to wood pellets but are caused by general degradation processes of wood, facilitated by drying at elevated temperature. Emission of carbon monoxide from wood materials at low temperatures (
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| 2. |
- Svedberg, U.R.A., et al.
(författare)
-
Hazardous off-gassing of carbon monoxide and oxygen depletion during ocean transportation of wood pellets
- 2008
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Ingår i: Annals of Occupational Hygiene. - : Oxford University Press (OUP). - 0003-4878 .- 1475-3162. ; 52:4, s. 259-266
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Tidskriftsartikel (refereegranskat)abstract
- Five ocean vessels were investigated for the characterization and quantification of gaseous compounds emitted during ocean transportation of wood pellets in closed cargo hatches from Canada to Sweden. The study was initiated after a fatal accident with several injured during discharge in Sweden. The objective with the investigation was to better understand the off-gassing and issues related to workers' exposure. Air sampling was done during transport and immediately before discharge in the undisturbed headspace air above the wood pellets and in the staircase adjacent to each hatch. The samples were analyzed with Fourier transform infrared spectroscopy and direct reading instruments. The following compounds and ranges were detected in samples from the five ships: carbon monoxide (CO) 1460-14650 ppm, carbon dioxide (CO2) 2960-21570 ppm, methane 79.9-956 ppm, butane equivalents 63-842 ppm, ethylene 2-21.2 ppm, propylene 5.3-36 ppm, ethane 0-25 ppm and aldehydes 2.3-35 ppm. The oxygen levels were between 0.8 and 16.9%. The concentrations in the staircases were almost as high as in the cargo hatches, indicating a fairly free passage of air between the two spaces. A potentially dangerous atmosphere was reached within a week from loading. The conclusions are that ocean transportation of wood pellets in confined spaces may produce an oxygen deficient atmosphere and lethal levels of CO which may leak into adjacent access spaces. The dangerous combination of extremely high levels of CO and reduced oxygen produces a fast-acting toxic combination. Measurement of CO in combination with oxygen is essential prior to entry in spaces having air communication with cargo hatches of wood pellets. Forced ventilation of staircases prior to entry is necessary. Redesign, locking and labeling of access doors and the establishment of rigorous entry procedures and training of onboard crew as well as personnel boarding ocean vessels are also important.
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