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Emission of Hexanal and Carbon Monoxide from Storage of Wood Pellets, a Potential Occupational and Domestic Health Hazard
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Occupational and Environmental Medicine.
2004 (English)In: Annals of Occupational Hygiene, ISSN 0003-4878, E-ISSN 1475-3162, Vol. 48, no 4, 339-349 p.Article in journal (Refereed) Published
Abstract [en]

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 arithmetic mean aldehyde level of 111 +/- 32 mg/m(3) was found in one warehouse, with a peak reading of 156 mg/m(3) [correction]. A maximum aldehyde reading of 457 mg/m(3) 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/m(3)), methanol (18 +/- 7 mg/m(3)) and carbon monoxide (56 +/- 4 mg/m(3)) 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/m(3) and carbon monoxide levels of 123 +/- 10 mg/m(3) were recorded inside such storage rooms. Elevated levels of hexanal (0.084 mg/m(3)) 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 (<100 degrees C) has not previously been reported in the literature. We postulate that carbon monoxide is formed due to autoxidative degradation of fats and fatty acids. A toxicological literature survey showed that the available scientific information on hexanal is insufficient to determine the potential risks to health. However, the data presented in this paper seem sufficient to undertake preventive measures to reduce exposure to hexanal.

Place, publisher, year, edition, pages
2004. Vol. 48, no 4, 339-349 p.
National Category
Medical and Health Sciences
Identifiers
URN: urn:nbn:se:uu:diva-91645DOI: 10.1093/annhyg/meh015PubMedID: 15191943OAI: oai:DiVA.org:uu-91645DiVA: diva2:164445
Note

Erratum in Annals of Occupational Hygiene, 4, 339–349.

DOI: 10.1093/annhyg/meh015

Available from: 2004-04-16 Created: 2004-04-16 Last updated: 2017-12-14Bibliographically approved
In thesis
1. Fourier Transform Infrared Spectroscopy in Industrial Hygiene Applications: Assessment of Emissions from and Exposures in Wood Processing Industries
Open this publication in new window or tab >>Fourier Transform Infrared Spectroscopy in Industrial Hygiene Applications: Assessment of Emissions from and Exposures in Wood Processing Industries
2004 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis evaluates the use of Fourier Transform Infrared Spectroscopy (FTIR) as an approach to the increasingly difficult air sampling challenges within the field of occupational and environmental hygiene. The application of FTIR is exemplified by the assessment of emissions from and exposures in the sawmill and pellet industries.

Open path FTIR was applied in the sawsheds and the terpene levels were monitored for several days. Traditional adsorbent sampling was used to evaluate the FTIR measurements. The volatile emissions from wood pellets were investigated in warehouses and in domestic storage rooms.

The installation of open path FTIR in the harsh sawmill environment proved useful, however, attention must be paid to vibrations, beam blockage and limited sensitivity. Adsorbent sampling showed good agreement with open path FTIR. The uncontrolled airflows in sawsheds caused significant underestimation of emission rates. By the use of FTIR and a tracer gas a more accurate estimate was obtained. The total emission from processing of Scots pine was estimated to 660 g/m3 of roundwood under bark, and can amount to 700 tons annually from a large sawmill.

Hexanal (111±32 mg/m3) and CO (56±4mg/m3) were recorded in pellet warehouses. Storage of wood pellets constitutes a potential occupational and domestic health hazard. Experiments from kiln drying of lumber 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. This is the first published report where low-temperature emission of carbon monoxide from wood materials is described.

The FTIR method is a significant advancement in measurement technology. The retrieved data offers unparalleled information. It offers robust, convenient and efficient monitoring of gases over extended periods. FTIR spectroscopy should be considered a standard technique within the field of occupational and environmental hygiene.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2004. 57 p.
Series
Comprehensive Summaries of Uppsala Dissertations from the Faculty of Medicine, ISSN 0282-7476 ; 1344
Keyword
Medicine, FTIR, Exposure, Emission, Saw mills, Wood pellets, Tracer gas, Monoterpenes, Hexanal, Carbon monoxide, Open path FTIR, Medicin
National Category
Dermatology and Venereal Diseases
Identifiers
urn:nbn:se:uu:diva-4225 (URN)91-554-5941-2 (ISBN)
Public defence
2004-05-11, MIC AULA, Matematiskt Informationsteknologiskt Centrum, Hus 6, Lägerhyddsvägen 2, Polacksbacken, Uppsala, 13:15
Opponent
Supervisors
Available from: 2004-04-16 Created: 2004-04-16Bibliographically approved

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