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Review Health effects of residential wood smoke particles: the importance of combustion conditions and physicochemical particle properties
Anette Kocbach B?lling<sup>1</sup><sup>*</sup>, Joakim Pagels<sup>2</sup>, Karl E Yttri<sup>3</sup>, Lars Barregard<sup>4</sup>, Gerd Sallsten<sup>4</sup>, Per E Schwarze<sup>1</sup> and Christoffer Boman<sup>5</sup>
<section> Author Affiliations
<sup id="ins1">1</sup> Division of Environmental Medicine, Norwegian Institute of Public Health, Oslo, Norway
<sup id="ins2">2</sup> Division of Ergonomics & Aerosol Technology (EAT), Lund University, Lund, Sweden
<sup id="ins3">3</sup> Department of Atmospheric and Climate Research, Norwegian Institute for Air Research, Kjeller, Norway
<sup id="ins4">4</sup> Department of Occupational and Environmental Medicine, Sahlgrenska University Hospital and Academy, University of Gothenburg, Gothenburg, Sweden
<sup id="ins5">5</sup> Energy Technology and Thermal Process Chemistry, Ume? University, Ume?, Sweden
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<section class="cit"> Particle and Fibre Toxicology 2009, 6:29 doi:10.1186/1743-8977-6-29
The electronic version of this article is the complete one and can be found online at: http://www.particleandfibretoxicolog...content/6/1/29
<table cellpadding="0" cellspacing="0"> <tbody> <tr><td>Received:</td><td>3 June 2009</td></tr> <tr><td>Accepted:</td><td>6 November 2009</td></tr> <tr><td>Published:</td><td>6 November 2009</td></tr> </tbody> </table>
? 2009 B?lling et al; licensee BioMed Central Ltd.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
</section> <section>Abstract
Background
Residential wood combustion is now recognized as a major particle source in many developed countries, and the number of studies investigating the negative health effects associated with wood smoke exposure is currently increasing. The combustion appliances in use today provide highly variable combustion conditions resulting in large variations in the physicochemical characteristics of the emitted particles. These differences in physicochemical properties are likely to influence the biological effects induced by the wood smoke particles.
Outline
The focus of this review is to discuss the present knowledge on physicochemical properties of wood smoke particles from different combustion conditions in relation to wood smoke-induced health effects. In addition, the human wood smoke exposure in developed countries is explored in order to identify the particle characteristics that are relevant for experimental studies of wood smoke-induced health effects. Finally, recent experimental studies regarding wood smoke exposure are discussed with respect to the applied combustion conditions and particle properties.
Conclusion
Overall, the reviewed literature regarding the physicochemical properties of wood smoke particles provides a relatively clear picture of how these properties vary with the combustion conditions, whereas particle emissions from specific classes of combustion appliances are less well characterised. The major gaps in knowledge concern; (i) characterisation of the atmospheric transformations of wood smoke particles, (ii) characterisation of the physicochemical properties of wood smoke particles in ambient and indoor environments, and (iii) identification of the physicochemical properties that influence the biological effects of wood smoke particles.
Background
Exposure to ambient particulate matter (PM) has been associated with a range of negative health effects, including increased morbidity and mortality from pulmonary and cardiovascular diseases [1-3]. Although residential wood combustion is a major source of particulate air pollution in many countries, relatively few studies have been performed to investigate the health effects associated with wood smoke exposure. The two most recent reviews on the topic concluded that the adverse health effects associated with wood smoke exposure in developed countries do not seem to be weaker than for ambient particles from other sources [4,5]. However, the reviewed literature suggested that the respiratory effects of wood smoke may be somewhat larger than the cardiovascular effects [5]. The use of wood or charcoal for heating or cooking during female adolescence was recently associated with chronic obstructive pulmonary disease later in life [6], providing further support for an association between wood smoke exposure and negative respiratory effects. In addition, a human inhalation study reported that wood smoke exposure affected both systemic and lung biomarkers, suggesting a potential impact of wood smoke particles also for cardiovascular diseases [7,8]. Recently, the International Agency for Research on Cancer (IARC) classified indoor emissions from household combustion of biomass fuel (mainly wood) as probably carcinogenic to humans (group 2A) [9].
The term residential wood smoke comprises emissions from a variety of biomass combustion appliances, such as open fireplaces, wood and pellet stoves, masonry heaters, and boilers for wood, wood chips and pellets [10-12] (see Additional file 1 for a brief description of the different types of combustion appliances). The combustion technology and air supply varies considerably between these different appliances, but also between old and new models of each type of appliance. In addition, the fuel type (e.g. wood logs, wood chips and pellets) and the condition of the fuel (e.g. moisture content and log size) also influence the efficiency of the combustion [11,13,14]. The physicochemical properties of particles emitted from residential biomass combustion differ considerably with combustion conditions and between combustion appliances [13,15]. Since epidemiological and experimental studies provide increasing evidence for the importance of physicochemical characteristics in the particle-induced biological effects [16,17], the differences in the physicochemical properties of particles originating from varying combustion conditions may influence their potential to induce biological effects...
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Anette Kocbach B?lling<sup>1</sup><sup>*</sup>, Joakim Pagels<sup>2</sup>, Karl E Yttri<sup>3</sup>, Lars Barregard<sup>4</sup>, Gerd Sallsten<sup>4</sup>, Per E Schwarze<sup>1</sup> and Christoffer Boman<sup>5</sup>
- * Corresponding author: Anette Kocbach B?lling
<section> Author Affiliations
<sup id="ins1">1</sup> Division of Environmental Medicine, Norwegian Institute of Public Health, Oslo, Norway
<sup id="ins2">2</sup> Division of Ergonomics & Aerosol Technology (EAT), Lund University, Lund, Sweden
<sup id="ins3">3</sup> Department of Atmospheric and Climate Research, Norwegian Institute for Air Research, Kjeller, Norway
<sup id="ins4">4</sup> Department of Occupational and Environmental Medicine, Sahlgrenska University Hospital and Academy, University of Gothenburg, Gothenburg, Sweden
<sup id="ins5">5</sup> Energy Technology and Thermal Process Chemistry, Ume? University, Ume?, Sweden
</section>
<section class="cit"> Particle and Fibre Toxicology 2009, 6:29 doi:10.1186/1743-8977-6-29
The electronic version of this article is the complete one and can be found online at: http://www.particleandfibretoxicolog...content/6/1/29
<table cellpadding="0" cellspacing="0"> <tbody> <tr><td>Received:</td><td>3 June 2009</td></tr> <tr><td>Accepted:</td><td>6 November 2009</td></tr> <tr><td>Published:</td><td>6 November 2009</td></tr> </tbody> </table>
? 2009 B?lling et al; licensee BioMed Central Ltd.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
</section> <section>Abstract
Background
Residential wood combustion is now recognized as a major particle source in many developed countries, and the number of studies investigating the negative health effects associated with wood smoke exposure is currently increasing. The combustion appliances in use today provide highly variable combustion conditions resulting in large variations in the physicochemical characteristics of the emitted particles. These differences in physicochemical properties are likely to influence the biological effects induced by the wood smoke particles.
Outline
The focus of this review is to discuss the present knowledge on physicochemical properties of wood smoke particles from different combustion conditions in relation to wood smoke-induced health effects. In addition, the human wood smoke exposure in developed countries is explored in order to identify the particle characteristics that are relevant for experimental studies of wood smoke-induced health effects. Finally, recent experimental studies regarding wood smoke exposure are discussed with respect to the applied combustion conditions and particle properties.
Conclusion
Overall, the reviewed literature regarding the physicochemical properties of wood smoke particles provides a relatively clear picture of how these properties vary with the combustion conditions, whereas particle emissions from specific classes of combustion appliances are less well characterised. The major gaps in knowledge concern; (i) characterisation of the atmospheric transformations of wood smoke particles, (ii) characterisation of the physicochemical properties of wood smoke particles in ambient and indoor environments, and (iii) identification of the physicochemical properties that influence the biological effects of wood smoke particles.
Background
Exposure to ambient particulate matter (PM) has been associated with a range of negative health effects, including increased morbidity and mortality from pulmonary and cardiovascular diseases [1-3]. Although residential wood combustion is a major source of particulate air pollution in many countries, relatively few studies have been performed to investigate the health effects associated with wood smoke exposure. The two most recent reviews on the topic concluded that the adverse health effects associated with wood smoke exposure in developed countries do not seem to be weaker than for ambient particles from other sources [4,5]. However, the reviewed literature suggested that the respiratory effects of wood smoke may be somewhat larger than the cardiovascular effects [5]. The use of wood or charcoal for heating or cooking during female adolescence was recently associated with chronic obstructive pulmonary disease later in life [6], providing further support for an association between wood smoke exposure and negative respiratory effects. In addition, a human inhalation study reported that wood smoke exposure affected both systemic and lung biomarkers, suggesting a potential impact of wood smoke particles also for cardiovascular diseases [7,8]. Recently, the International Agency for Research on Cancer (IARC) classified indoor emissions from household combustion of biomass fuel (mainly wood) as probably carcinogenic to humans (group 2A) [9].
The term residential wood smoke comprises emissions from a variety of biomass combustion appliances, such as open fireplaces, wood and pellet stoves, masonry heaters, and boilers for wood, wood chips and pellets [10-12] (see Additional file 1 for a brief description of the different types of combustion appliances). The combustion technology and air supply varies considerably between these different appliances, but also between old and new models of each type of appliance. In addition, the fuel type (e.g. wood logs, wood chips and pellets) and the condition of the fuel (e.g. moisture content and log size) also influence the efficiency of the combustion [11,13,14]. The physicochemical properties of particles emitted from residential biomass combustion differ considerably with combustion conditions and between combustion appliances [13,15]. Since epidemiological and experimental studies provide increasing evidence for the importance of physicochemical characteristics in the particle-induced biological effects [16,17], the differences in the physicochemical properties of particles originating from varying combustion conditions may influence their potential to induce biological effects...
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