Physicochemical and toxic properties of particulate emissions from different small-scale wood combustion appliances

Transkriptio

1 UNIVERSITY OF EASTERN FINLAND DEPARTMENT OF ENVIRONMENTAL SCIENCE Fine particle and aerosol technology laboratory PL KUOPIO Physicochemical and toxic properties of particulate emissions from different small-scale wood combustion appliances TEKES Project 40296/07, Final Report Jarkko Tissari (Ed.) 2/2011 ITÄ-SUOMEN YLIOPISTON YMPÄRISTÖTIETEEN LAITOKSEN JULKAISUSARJA PUBLICATION SERIES OF DEPARTMENT OF ENVIRONMENTAL SCIENCE UNIVERSITY OF EASTERN FINLAND YMPÄRISTÖTIETEEN LAITOS, ITÄ-SUOMEN YLIOPISTO DEPARTMENT OF ENVIRONMENTAL SCIENCE, UNIVERSITY OF EASTERN FINLAND PO Box 1627, FI KUOPIO, FINLAND ISSN

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3 PREFACE 3 PREFACE This work is the final report of the research project Particle emissions from small-scale wood combustion appliances: chemical-toxicity model (Polttotekniikaltaan erilaisten puun pienpolttolaitteiden hiukkaspäästöt ja terveys: kemia-toksisuusmalli) which is a part of the Finnish-Austrian collaborative project on small-scale biomass combustion: physicochemical and toxic properties of particulate emissions. The combustion experiments for this study were done at the University of Eastern Finland (previously University of Kuopio), Department of Environmental Science, Fine Particle and Aerosol Technology Laboratory (FINE), in Kuopio between the November 2008 and May 2009 in close cooperation with National Institute for Health and Welfare (THL), Department of Environmental Health (Kuopio) and Finnish Meteorological Institute (FMI), Aerosol Research Group (Helsinki). The research partners in the project and the representatives of the organizations in the management committee were: Prof. Jorma Jokiniemi (responsible leader of the project), Ph.D. Jarkko Tissari (secretary of the management committee, and ) and M.Sc. Kati Nuutinen (secretary of the management committee, ), University of Eastern Finland, Prof. Maija-Riitta Hirvonen and Doc. Raimo O. Salonen, National Institute for Health and Welfare, Prof. Risto Hillamo, Finnish Meteorological Institute, Marjatta Aarniala, The Finnish Funding Agency for Technology and Innovation (TEKES), Juha Timonen (chair of the management committee), Tulikivi Ltd, Martti Romu, Wienerberger Ltd, Antti Hirvelä, Bet-Ker Ltd, Johannes Uusitalo, NunnaUuni Ltd, Timo Määttä, Motiva Ltd, Mervi Sihvonen, Turun Uunisepät Ltd, Jari Valtonen, Narvi Ltd, Leena Siltaloppi ( ) and Kauko Isomöttönen ( ), Vapo Ltd, Kauko Janka ( ) and Ville Niemelä ( ), Dekati Ltd and Katja Outinen ( ), Ministry of the Environment. Finnish-Austrian collaborative project was executed with Bioenergy2020+ in Graz with Prof. Ingwald Obernberger and Dr. Thomas Brunner. Also several scientists contributed to the project: Heikki Lamberg, Olli Sippula, Annika Hukkanen, Terhi Penttilä, Jarno Ruusunen, Mika Ihalainen, Tommi Karhunen and Pentti Willman (University of Eastern Finland), Maija Tapanainen, Pasi Jalava, Mikko Happo, Pasi Hakulinen and Jorma Mäki-Paakkanen (National Institute for Health and Welfare) and Karri Saarnio, Anna Frey, Kimmo Teinilä and Minna Aurela (Finnish Meteorological Institute). On behalf of the project group, I am grateful to TEKES and manufacturers the funding of the project. Also contributions of all project partners, management committee and especially writers of this report (Heikki Lamberg, Maija Tapanainen, Karri Saarnio and Anna Frey) are gratefully acknowledged. Kuopio, June 2011 Jarkko Tissari

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5 CONTENT 5 Content 1 BACKGROUND PHYSICOCHEMICAL PROPERTIES OF PARTICULATE EMISSIONS EXPERIMENTAL SET-UP Combustion appliances, operation and fuels Emission measurements The FMI s emission measurements EXPERIMENTAL PERIODS RESULTS OF FINE LABORATORY MEASUREMENTS The gaseous emissions The particle mass emission factors The particle number emission and number size distributions Particle chemical composition The PAH emissions RESULTS OF FMI MEASUREMENTS Particulate mass Water-soluble organic carbon Wood combustion tracers Inorganic ions Organic ions Size distributions TOXICOLOGICAL RESPONSES INDUCED BY PARTICLES INTRODUCTION The role of macrophages and epithelial cells in immune response against inhaled particles Toxicological analysis MATERIALS AND METHODS Sample preparation Study design of toxicological analyses RESULTS Cell death and other changes in the normal cell cycle Production of the inflammatory mediators (TNF-, MIP-2 and IL-6) DNA damage DISCUSSION Relative toxicological responses The effect of chemical composition on particle-induced toxicological properties SUMMARY AND CONCLUSIONS LITERATURE APPENDIXES... 35

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7 1. BACKGROUND 7 1 BACKGROUND Fine particles (PM2.5: Particle Mass below aerodynamic size of 2.5 µm) are one of the most important pollutant in outdoor air (Pope and Dockery, 2006). The impact of airborne particles on health is very varied, ranging from causing mild, short-lived symptoms to contributing to the onset or worsening of chronic conditions and premature death (Dockery et al., 1993; Kappos et al., 2004; Salonen and Pennanen, 2007). A safe threshold level for fine particle concentrations in urban air cannot yet be determined (WHO, 1994). Current level of thoracic (PM10) and fine particles are associated with about premature annual deaths in Europe (Directive 2008/50/EC), hospital admission, and restricted activity in tens of millions of children and subjects with chronic cardiovascular and pulmonary disease (WHO 2003; 2005; U.S. EPA, 2004). Residential wood combustion (RWC) for heat production has been assessed to be a major source of fine particle mass emissions, particulate polyaromatic hydrocarbons (PAHs) and certain gaseous pollutants such as volatile organic compounds (VOCs) throughout Europe (e.g. Olsson et al., 1997; Christensen et al., 1998; Salonen and Pennanen, 2007). In Finland, the main source of fine particles is long-range transport, whereas traffic, energy plants, industrial processes and residential wood combustion (RWC) are the most important stationary emission sources. A recent study reported that RWC accounted for 25% of the stationary combustion emissions in Finland in 2000, based on primary PM2.5 (Karvosenoja et al., 2008). On the other hand, it has been estimated that RWC can produce locally as much as 20 90% of the wintertime fine particle emissions (Muhlbaler Dasch, 1982; Boman et al., 2003a). According to an EU agreement, the use of renewable energy in Finland has to increase from 28% to 38% by This also requires an increase in all kinds of wood energy. The emissions from RWC have been demonstrated to be highly variable (Nussbaumer, 2003; Johansson et al., 2003; 2004; Sippula et al., 2007a; Tissari et al., 2005; 2007a; 2009). In small combustion units, the local atmosphere and temperature vary considerably depending on the grate and burner. There are also many different uncontrolled factors that also affect the combustion conditions. For example, numerous types and models of wood combustion appliances are in use, and wood fuel can originate from several tree species. The operational practices (e.g., fuel seasoning, combustion patterns, combustion rates, kindling approaches etc.) of RWC also vary widely. Based on the several previous studies, primary factors that affect the emissions are relatively well-known (e.g. Hedberg et al., 2002; Johansson et al., 2004; Koyuncu and Pinar, 2007; Tissari et al., 2007b; Sippula et al., 2007a). Recent results show that the poor operational practice (smouldering combustion) increases the fine particle emissions remarkably (Tissari et al., 2008a; Hytönen et al., 2009). In addition, the portion of organic fraction, emissions of PAH compounds and genotoxicity of particles increases (Tissari et al., 2008a; Frey et al., 2008; Hytönen et al., 2009; Jalava et al., 2010a). In complete combustion conditions (e.g. pellet boiler) the the fine particles composed mainly of alkali metal compounds. In modern masonry heaters, fine particles include also organic and elemental carbon, which are the main compounds in conventional appliances such as sauna stoves (Tissari et al., 2009). Primarily due to their health effects, there is a need to decrease the particle and gaseous emissions from wood combustion in small scale appliances. Because the mechanisms of the health effects are not yet known exactly, studying both fine particle physical and chemical properties is important (Lightly et al., 2000). These properties (e.g. particle size and morphology, number and mass concentration, chemical composition) are dependent on combustion conditions. However, there has been lack in the knowledge concerning fine particle emis-

8 8 Physicochemical and toxic properties of particulate emissions from RWC sions from masonry heaters and sauna stoves and their composition during different combustion conditions. Especially, the health related emissions (e.g. PAHs) and toxicological properties of fine particles have not been well-known. In addition, there is need to knowledge of effects of fine ash particles from complete combustion conditions on health. Thus, there is actual need to get detailed information from the particle and gas emissions and their connection to health responses from small scale appliances. In this study, physicochemical and toxicological properties of particulate emissions were widely studied from RWC appliances. The study concentrated the experiments in different type of masonry heaters, a sauna stove and a pellet boiler. The measurements were performed extensively from different combustion conditions with taking the samples during different combustion phases (firing, gasification) as well as during the whole combustion cycle and continuous, complete combustion (pellet boiler).

9 2. PHYSICOCHEMICAL PROPERTIES OF PARTICULATE EMISSIONS 9 2 PHYSICOCHEMICAL PROPERTIES OF PARTICULATE EMISSIONS Heikki Lamberg 1, Jarkko Tissari 1, Kati Nuutinen 1, Annika Hukkanen 1, Terhi Penttilä 1, Jarno Ruusunen 1, Mika Ihalainen 1, Tommi Karhunen 1, Pentti Willman 1, Jorma Jokiniemi 1,2 1 University of Eastern Finland, Department of Environmental Science, Fine particle and aerosol technology laboratory, Kuopio, Finland 2 VTT Technical Research Centre of Finland, Fine Particles, Espoo, Finland Karri Saarnio, Anna Frey, Kimmo Teinilä, Minna Aurela, Risto Hillamo Finnish Meteorological Institute, Aerosol Research Group, Helsinki, Finland The combustion tests for this study were done at the Fine Particle and Aerosol Technology Laboratory, University of Eastern Finland, in Kuopio (previously University of Kuopio). The measurement campaign was done between the November 2008 and May In the following chapters the combustion tests are generally described. Figure 1. Experimental setup.

10 10 Physicochemical and toxic properties of particulate emissions from RWC 2.1 EXPERIMENTAL SET-UP Combustion appliances, operation and fuels Seven different small-scale combustion appliances that can be used in households were tested. Combustion appliances tested here can be divided into three appliance categories: masonry heaters, sauna stoves and pellet boilers. Four of these appliances were conventional masonry heaters, one modern masonry heater, a sauna stove and a pellet boiler. Modern masonry heater differs from the conventional ones by its air-staging procedure; combustion air in conventional masonry heaters is led through the grate and through the door in the conventional technology, where as in the modern combustion technology only part of the combustion air is led in through the grate and most of the air is led to the flame above the fuel bed. The pellet boiler used in the tests also applied air-staging. Table 1. Description of the combustion situations, appliances, sampling times and fuel. About 200 g of kindling were used in the ignition in every combustion test. EFC, IBC, CBC1, CBC2, CBC3, IEBC include cycle with batch additions and ignition phases, which also take place in normal operation. IBC/34, CBC2/F, CBC3/23 and IEBC/S include specific combustion situations that take place within the cycles. EFC Experiment 1, 4 tests Description of situations Efficient combustion Combustion appliance Pellet boiler Collection time Continuous combustion, 2 3h Batch and fuel Commercial wood pellet IBC Experiment 2, IBC/34 3 tests CBC1 CBC2 CBC2/F Experiment 3, 3 tests Experiment 4, 3 tests CBC3 Experiment 5, CBC3/23 3 tests CBC4 IEBC IEBC/S Experiment 6, 3 tests Experiment 7, 3 tests Improved batch combustion Conventional batch combustion Conventional batch combustion Conventional batch combustion Conventional batch combustion Inefficient batch combustion Modern masonry heater Conventional masonry heater 1 Conventional masonry heater 2 Conventional masonry heater 3 Conventional masonry heater 4 Sauna stove Cycle, 120 min 3. and 4. batch, 50 min Cycle, 55 min Cycle, 140 min Firing phase, beginning of the 2. batch, 15 min Cycle, 65 min 2. and 3. batches, 40 min Cycle, 50 min Cycle, 55 min Ignition batch and 2. batch, min 1. batch 10x400g, other batches 4x1 kg 1. batch 7x0.23 kg, other batches 5x0.48 kg 1. batch 3x1 kg, other batches 3x1.3 kg 1. batch 7x0.43 kg, other batches 4x0.75 kg 1 batch 7x1 kg + 5x200g 1. batch 5x0.31 kg, 2. batch 6x0.53 kg, 3. batch 5x0.64 kg Each of the combustion appliances was used according to manufactures operation manual. In every combustion test, the appliances were kept at room temperature and they were left to cool down after each test. An ignition batch, described in Table 1, was set on the bottom of the appliance s fire chamber, and 200 g of wood stick and chippings were placed on top of wood logs as kindling to ensure sufficient start-up. The batch was ignited from top with matches. Birch wood was used in all of the log fuelled appliances with varying sizes of log batches, and commercial wood pellet was used in the pellet boiler. Primary pellet raw material was pine. Logs were relatively dry since it was stored inside before the tests; the moisture content was approximately 10-13% and 8% in the pellet fuel.

11 2. PHYSICOCHEMICAL PROPERTIES OF PARTICULATE EMISSIONS Emission measurements Each combustion appliance was attached to about 3 m high chimney (Figure 1). Flue gases were led outside through a hood using a flue gas fan. Gaseous emissions (CO, NOX, OGC, O2, HxCy, etc.) were measured in the hot flue gas with two gas analyzers: ABB fas analyzer (Hartman&Braun) and FTIR gas analyzer (Gasmet Oy). Fine particle samples were taken from a chimney and diluted with three different dilution systems. 1) Particle sample for chemical (ions, polyaromatic hydrocarbons (PAH)) and toxicological analyzes was diluted with porous tube diluter (PRD). Sample was collected with a Dekati Gravimetric Impactor (DGI, Dekati Inc.). Toxicological analyzes were done at the National Institute for Health and Welfare from this sample. 2) Particle samples for OC/EC analyzes and mass-size distribution (Dekati Low Pressure Impactor (DLPI), Dekati Oy) were diluted with porous tube diluter and ejector diluter (PRD+ED). In dilution systems 1 and 2, dilution air was dry and particle free, and the flow was controlled with a mass flow controller. 3) A heated sample line transported part of the flue gas to a dilution tunnel. Dilution air for dilution tunnel was room air from the laboratory, which was filtered for particles, OGC and NOX. Dilution ratio (the amount of dilution) was calculated from the difference of CO2 concentration in raw flue gas and in diluted sample. Finnish Meteorological Institute made their sampling in the dilution tunnel. Online particle measurement devices Electrical Low Pressure Impactor (ELPI, Dekati Oy) and Fast Mobility Particle Sizer (FMPS, TSI Inc.) measured particle number-size distributions in the dilution tunnel. In addition, temperatures of the flue gas and the diluted samples were measured with type-k thermometer. Because dilution is known to have effects on particle properties, the dilution ratio of dilution system 1) and 2) were kept approximately same in each test to keep the samples well comparable with each other. Organic carbon and elemental carbon were analyzed from quartz filter using a Carbon Aerosol Analyzer from Sun Laboratories Inc. Concentrations of major inorganic ions (Cl -, NO3-, SO 4 2-, Na +, NH4 +, K +, Mg 2+, and Ca 2+ ) were analyzed using two Dionex ICS-2000 (Dionex Corporation, Sunnyvale, CA, USA) ion chromatography systems. Twelve different elements (Al, As, Cd, Co, Cu, Cr, Pb, Mn, Ni, Fe, Zn and V) were analyzed with an ICP-MS (Perkin Elmer Sciex Elan 6000, Perkin-Elmer Corp., Waltham, MA, USA). Polyaromatic hydrocarbons (PAH) compounds in particulate matter samples were identified and quantified comparing against a mixture of standard compounds comprising of 30 commercially available PAHs The FMI s emission measurements The FMI Aerosol Research group participated in the emission measurements of the pellet boiler (Experiment 1, Table 1), of the sauna stove (Experiment 7, Table 1) and in those of one conventional masonry heater (Experiment 5) in the Fine particle and aerosol technology laboratory at the University of Eastern Finland. The emission particle samples were collected with following methods: o PM1-sampler that was constructed of a pre-impactor that removed the particles with aerodynamic diameter greater than 1 µm from the sample flow, followed by a filter cassette. Polytetrafluoroethylene (PTFE) membrane filters were used as a sampling material. o Small deposit area impactor (SDI) was used to segregate the particles into 12 size classes in the range of µm. The sampling material used was polycarbonate foil that was greased with a thin layer of Apiezon L-vacuum grease.

12 12 Physicochemical and toxic properties of particulate emissions from RWC o Gravimetric analysis of particulate mass was made by weighing the PTFE filters before and after PM1 sample collection. The balance was Mettler UMT2 with readability of 1 µg. The SDI samples were not weighed. o Water-soluble organic carbon (WSOC) was determined extracting one quarter of the PTFE filters in deionized water and analysing the carbonaceous content of the aqueous extract with a Shimadzu TOC-VCPH total carbon analysator with a high sensitive catalyst. o Tracer compounds of incomplete burning of biomass (monosaccharide anhydrides (MAs), such as levoglucosan, mannosan, and galactosan) were determined from aqueous extract of one quarter of PTFE filters using a high-performance anionexchange chromatograph coupled to a quadrupole mass spectrometer (HPAEC-MS). The HPAEC-MS method for determination of MAs was developed during this project (Saarnio et al., 2010). o Selected water-soluble inorganic anions and cations and organic anions were determined extracting one quarter of PTFE filters in deionized water and analysing with a Dionex ICS-3000 ion chromatograph coupled to a conductivity cell and a quadrupole mass spectrometer (IC-MS). The selected ions included: ammonium, potassium, sodium, chloride, nitrate, phosphate, sulphate, methane sulphonate, acetate, formate, glyoxylate, oxalate, malate, maleate, malonate, succinate, adipate, azelate, pinicate, and pinonate. The ion determination was made both for the PM1 samples on PTFE filters and for the size-segregated SDI samples. o In part of the emission samples from the sauna stove and the conventional masonry heater, there were problems with the dissolution with water. On the collected PTFE filters, a hydrophobic surface had formed of the sample material. Therefore the dissolution had probably not been quantitative. This may have affected the determination results of the water-soluble compounds. In the case of the pellet boiler samples, no such problem existed. 2.2 EXPERIMENTAL PERIODS Collection times and batch information are presented in Table 1. It shows the abbreviations of the different combustion tests, test durations, appliance information and batch information. Sampling times were selected to represent different kinds of combustion situations in normal small-scale combustion. Selected combustion situations and their emissions may not represent typical average emissions from the types of appliances used in this study, but they represent the average values of emissions from different combustion situations. Combustion situations are affected by the appliance type, use of the appliance and fuel properties. Emissions over specific combustion situations can be related to the properties of the produced particles and their toxicological responses. However, particle number emissions and gas emissions are described both from the combustion cycle, as well as from each combustion situations (sampling time for toxicological studies). Sampling and collection times are divided into different categories according to the individual combustion situation in the different combustion appliances. The particle samples in EFC were collected from a small-scale pellet boiler with 25 kw maximum output power, which represented modern small-scale combustion technology. In CBC1, the sample collection period was 55 minutes over combustion cycle including the ignition phase and three batches. In CBC2 firing phase (CBC2/F), the sample time was 15 minutes from the beginning of the second batch to obtain a

13 2. PHYSICOCHEMICAL PROPERTIES OF PARTICULATE EMISSIONS 13 sample of PM1 from a firing phase in conventional masonry heater. In CBC3 batches 2 and 3 (CBC3/23), the sample time was 40 minutes during second and third batches. It represented the relatively good combustion conditions in the CBCs. In CBC4, sampling time was 50 min including one large batch. In IBC batches 3 and 4 (IBC/34), the collection time was 50 minutes during the third and fourth batches. In IEBC, sampling was conducted during the start (IEBC/S); ignition and the second batch. In the FMI s measurements the sampling time in the pellet boiler measurements was four hours (four samplings in total). The emitted combustion air was diluted with a dilution ratio of about 100. In the measurements of the sauna stove and the conventional masonry heater, the samplings included the emissions of the ignition batch and two addition batches and the sampling duration was either 55 or 65 minutes (six samplings from the sauna stove, five from the masonry heater). The used dilution ratios were in the range of for the masonry heater emissions and for the sauna stove. a after the dilution tunnel+ed, b after PRD+ED+ED. Table 2. Combustion and sampling parameters of the measurements. O 2 (%) DR Sample temperature ( o C) Flue gas PRD+ DGI Dilution tunnel PRD+ ED PRD+ DGI Dilution tunnel PRD+ ED temperature ( o C) EFC IBC/ a a IBC a 27 a 242 CBC CBC2/F b b CBC b 24 b 96 CBC3/ CBC3/ CBC b b 166 IEBC/S IEBC a) after the dilution tunnel+ed, b) after PRD+ED+ED. 2.3 RESULTS OF FINE LABORATORY MEASUREMENTS Dilution ratios and temperatures were measured during the test periods and average values are presented in Table 2. The emission factors from continuous measurements are presented as an average of all measured data during the sampling period (Table 3 7) The gaseous emissions Gaseous emission factors and particle number emissions factors during the toxicological sampling are presented in Table 3 and 4. During the sampling times CO emission factors varied between 80 mg/mj (EFC) and 4400 mg/mj (IEBC/S) and OGC emission factors 0.96 mg/mj (EFC) and 1050 mg/mj (IEBC/S).

14 14 Physicochemical and toxic properties of particulate emissions from RWC Generally, pellet boiler produced the smallest gaseous emissions and sauna stove the largest ones. In conventional masonry heaters, CBC3 produced clearly lower emissions compared to CBC1 and CBC2. On the other hand, emissions of CO and OGC were lower from IBC than from CBCs. This shows that air-staging has decreased the gaseous emissions that have formed in incomplete combustion. Combustion controlled pellet boiler, which worked with continuous combustion produced significantly lower gaseous emissions than batch combustion appliances. Table 3. Gas emissions (mg/mj) of different combustion situations. Carbon monoxide (CO), organic gaseous compounds (OGC) and nitrogen oxide (NOX) were measured with the ABB gas analyzer, while hydrogen chloride (HCl), methane (CH4) and benzene (C6H6) were measured with the FTIR gas analyzer. CO OGC NO X HCl CH 4 C 6 H 6 EFC IBC n/a n/a n/a IBC/ n/a n/a n/a CBC CBC CBC2/F CBC CBC3/ CBC IEBC n/a n/a n/a IEBC/S Table 4. Emissions of PM1, carbon compounds, number emissions and GMD. PM1, EC, OC, CO3, mg/mj; NTot, #/MJ; GMD, nm. PM 1 EC OC CO 3 N Tot GMD EFC E IBC 8.4E IBC/ E CBC E CBC2 1.2E CBC2/F E CBC3 3.1E CBC3/ E CBC E IEBC 7.3E IEBC/S E The particle mass emission factors Particle emissions (PM1) factors were only collected during the selected combustion situations. The results show that the emissions varied significantly between different combustion situations. Similarly to the gaseous emissions factors, EFC produced the smallest PM1 emis-

15 2. PHYSICOCHEMICAL PROPERTIES OF PARTICULATE EMISSIONS 15 sions and IEBC/S the largest emissions. Emissions of organic carbon (OC) and elemental carbon (EC) show that there are basically none of these components from EFC. On the other hand, when batch combustion is applied, OC and EC are always present. This confirms the findings from gaseous emissions that there are emissions of incomplete combustion (OC, EC, CO, OGC) when batch combustion is applied The particle number emission and number size distributions The averaged number emission factors (NTot) and geometric mean diameters (GMD) over combustion situations are presented in Table 4. GMD values calculated from ELPI data varied between 60 nm and 142 nm. The largest GMD values were measured from CBC2 and the smallest from EFC. The number emission was smallest in CBC2/F, 1.9E+13 #/MJ and highest from CBC1, 1.0E+14 #/MJ. The Figure 2 shows bimodal number size distributions in IEBC/S, CBC4 and CBC2/F. These combustion situations are also those with the most incomplete combustion, according to the emissions of gases, EC and OC. It has been previously reported that particle size increases when combustion situation get worse (Tissari et al., 2008a). In CBC2/F, the low flue gas temperature (Table 2) provides also evidence that the residence time inside the appliance has been relatively long, giving the particles more time for coagulation or agglomeration, leading to a smaller number concentration and a larger particle size. 1.4E E+14 Number dn/dlogdp [#/MJ] 1.0E+14 J ] / M [# p 8.0E+13 g D lo / d N d r 6.0E+13 e b m u N 4.0E+13 CBC1 CBC4 CBC3/23 CBC2/F IBC/34 EFC IEBC/S 2.0E E Particle size (µm) Figure 2. The average number size distributions from different combustion situations Particle chemical composition Most of the particulate matter consists of inorganic alkali metal components in EFC, shown in Tables 5 and 6. The most abundant chemical species were K +, SO4 2-, Cl - and Na +. These components vaporize in hot flame temperatures from ash forming elements in the fuel.

16 16 Physicochemical and toxic properties of particulate emissions from RWC When flue gases cool down, they form particles. The smallest emissions of alkali metals and metals were seen in CBC2/F. It can be concluded that its combustion temperature was most likely the lowest of all appliances tested here, since the evaporation of these components is strongly related to combustion temperature. However, the temperature inside the combustion chamber was not measured. Interestingly, the PM1 chemical properties are similar with IBC/34 and CBC3/23, even though the air-staging in IBC clearly affected the gas emissions. This shows that the air-staging in IBC did not affect the oxidation of OC and EC significantly. Table 5. Emissions of PM1 ion compounds (mg/mj). Na NH 4 K Mg Ca Cl SO 4 NO 3 EFC E <DL <DL IBC/34 <DL <DL E <DL 0.11 CBC1 <DL <DL 9.0 <DL 8.8E CBC2/F 9.5E E CBC3/23 <DL E CBC <DL 5.4 <DL <DL IEBC/S 0.67 <DL 0.89 <DL <DL <DL, below detection limit. Table 6. Emissions of PM1 metal compounds (µg/mj). Cd Co Cr Cu Mn Ni Pb V As Fe Zn EFC 0.17 <DL <DL 3.9 <DL IBC/ <DL <DL CBC <DL <DL CBC2/F <DL CBC3/ <DL IEBC/S 1.9 <DL 1.5 <DL <DL <DL <DL <DL 970 <DL, below detection limit The PAH emissions Different combustion situations in CBCs are at a similar level in total PAHs, but the differences between IBC/34 and different CBCs were greater than in PM1. In addition, when comparing PAH contents and PM1 emissions from IBC/34 and EFC, it can be seen that the difference in PAHs between these two combustion conditions are greater than indicated by the PM1 emissions. This highlights that the impact of improved combustion technology on the particulate PAH seem to be more significant than would be predicted from the PM1 emissions, gas emissions or other particle chemical properties. The distributions of the different PAH-species varied with the different combustion situations. In all combustion situations, phenanthrene, fluoranthene and pyrene were the most common PAH compounds, except in CBC3/23 where cyclopenta[c,d]pyrene was the third most common PAH compound.

17 2. PHYSICOCHEMICAL PROPERTIES OF PARTICULATE EMISSIONS 17 Table 7. Polycyclic aromatic hydrocarbon (PAH) contents in PM1 samples, total PAHs, genotoxic PAHs and PAH/PM1. Genotoxic PAH compounds defined on the basis of the WHO/IPCS criteria (WHO 1998). Determination limit of the method 0.1 ng/mg. <DL, under determination limit. PAH compounds, ng/mg in PM 1 EFC IBC/34 CBC1 CBC2/F CBC3/23 IEBC/S Naphthalene <DL <DL 5.7 Acenaphthylene <DL Acenaphthene <DL <DL Fluorene <DL Phenanthrene Anthracene <DL Methylphenanthrene Fluoranthene Pyrene Benzo[c]phenanthrene Benzo[a]anthracene Cyclopenta[c,d]pyrene 0.2 <DL Triphenylene Chrysene Methylchrysene <DL Benzo[b]fluoranthene Benzo[k]fluoranthene <DL Benzo[j]fluoranthene Benzo[e]pyrene Benzo[a]pyrene Perylene <DL Indeno[1,2,3-cd]pyrene <DL Dibenzo[a,h]anthracene <DL Benzo[g,h,i]perylene Anthanthrene <DL Dibenzo[a,l]pyrene <DL <DL Dibenzo[a,e]pyrene <DL <DL Coronene <DL Dibenzo[a,i]pyrene <DL <DL <DL <DL Dibenzo[a,h]pyrene <DL <DL Total PAHs Total genotoxic PAHs PAH/PM 1 (%) 6.0E Proportion of genotoxic PAHs from the sum of all PAHS

18 18 Physicochemical and toxic properties of particulate emissions from RWC 2.4 RESULTS OF FMI MEASUREMENTS Particulate mass The fine particle emissions (Figure 3) differed remarkably between the different combustion appliances. The clearly highest particulate mass concentrations were measured for sauna stove emissions. The fine particle emissions from the sauna stove were eight times higher than from the conventional masonry heater and 16 times higher than from the pellet boiler (concentration ratios 16:2:1, sauna stove/masonry heater/pellet boiler). Figure 3. Particulate mass concentrations of the combustion appliances Water-soluble organic carbon In this project, one main object of FMI Aerosol Research group was to study the watersoluble content of the particulate matter. The water-solubility of the particulate matter was very different in the emissions from the pellet boiler compared to those from the sauna stove and the conventional masonry heater. In the pellet boiler emissions, the particulate matter consisted mostly of water-soluble material (mainly ash-forming ions) whereas more than 90% of particulate emissions from the sauna stove and the masonry heater were waterinsoluble (presumably mainly elemental carbon and water-insoluble organic compounds that could not have been measured from these samples). The ratios of the WSOC concentrations of the fine particle emissions (concentration ratios 15:1:1, sauna stove/masonry heater/pellet boiler) were almost similar to those of particulate mass concentrations. It was expected that from the pellet boiler emissions, only low concentration of WSOC would be measured. Contrary to the expectations, WSOC were on the same concentration level as from the conventional masonry heater. However, this could be due to the inaccuracy of the determination method with the low concentration samples and other methodological reasons Wood combustion tracers High concentrations of MAs in particulate emissions are a signal of incomplete combustion of biomass. In the experiments of PUPO-poltto project, the clearly highest concentrations of MAs were determined in samples of the sauna stove. The MAs concentrations were remarkable also in samples from masonry heater, whereas in the samples from the pellet boiler, the MAs concentrations were close to the detection limit of these compounds in the HPAEC-MS method. The MAs emissions from pellet boiler were almost negligible compared to those of the other two combustion appliances. The ratios of MAs between the ap-

19 2. PHYSICOCHEMICAL PROPERTIES OF PARTICULATE EMISSIONS 19 pliances were 320:140:1. The contribution of MAs to WSOC was high in PM1 samples from the conventional masonry heater (39%) and from the sauna stove (10%) while from pellet boiler it was only 0.25%. It can be stated that the combustion in the pellet boiler was of good quality whereas in the other two appliances the combustion was more or less incomplete. Figure 4. Chemical mass closures of the particulate emissions from pellet boiler (a), sauna stove (b), and masonry heater (c) Inorganic ions The fine particle emissions from the pellet boiler were mainly composed of inorganic ash forming components (i.e., inorganic ions). Compared to the ion emissions from the pellet boiler, the ion emissions from the conventional masonry heater and the sauna stove were minor. The ratios of the mass concentration sums of the selected ions were 2:3:13 (sauna stove/masonry heater/pellet boiler) between the combustion appliances, respectively. The main ions in the pellet boiler emissions were potassium, sulphate, sodium, and chloride, whereas in the particulate emissions of the sauna stove and the conventional masonry heater, the main ions were potassium, sulphate, chloride, and nitrate Organic ions The concentrations of organic ions were significantly lower than those of inorganic ions: in the PM1 emissions from the pellet boiler there were 125 times more inorganic ions than organic ions, from the sauna stove 20 times more, and from the conventional masonry heater 13 times more. The concentration of oxalate is commonly used as a tracer for biomass burn-

20 20 Physicochemical and toxic properties of particulate emissions from RWC ing in ambient air samples. However, the concentrations of primary oxalate were minor in this study compared to other biomass burning tracers, such as potassium and levoglucosan (MAs). The results of this study showed that organic ions are probably formed in particles when the combustion emissions are mixed with the ambient air (secondary formation). In this study, the sample collections were made directly from the primary emissions of the combustion Size distributions In the size-distributions of inorganic and organic ions, it was noted that the particulate emissions of these compounds from the pellet boiler were concentrated nearly totally in the particles smaller that 500 nm. The ion emissions of the conventional masonry heater and, especially, those of the sauna stove were distributed in a wider size-range, however, concentrating in the particles smaller than 1 µm. Figure 5. Mass size distributions of inorganic ions (a) and organic ions (b).

21 3. TOXICOLOGICAL RESPONSES INDUCED BY PARTICLES 21 3 TOXICOLOGICAL RESPONSES INDUCED BY PARTICLES Maija Tapanainen 1, Pasi I. Jalava 2, Mikko S. Happo 2, Pasi Hakulinen 1, Raimo O. Salonen 1, Jorma Mäki-Paakkanen 1 ja Maija-Riitta Hirvonen 1,2 1 National Institute for Health and Welfare (THL), Department of Environmental Health, Kuopio, Finland 2 University of Eastern Finland, Department of Environmental Science, Kuopio, Finland 3.1 INTRODUCTION The role of macrophages and epithelial cells in immune response against inhaled particles Macrophages are white blood cells of the innate immune system which encounter inhaled particles in the respiratory system. They have a special ability to uptake large particles and destroy or clear them from the respiratory system. Furthermore, they also stimulate lymphocytes and other immune cells to respond to the pathogen by producing inflammatory mediators. If the size of the particles is very small i.e. ultrafine particles, the role of macrophages is diminished and the particles can pass on the bloodstream via lung epithelial cells. Bronchial epithelial cells line the bronchi and they also take part in host defense reactions against inhaled particles Toxicological analysis Cell death and other changes in the normal cell cycle Cell death can be mediated by intra - or extracellular signals. Generally, cells have two different mechanisms for dying. In acute cell death, damaged cells dissolve and release their contents to the intermediate state of the cells. Usually acute cell death is followed by secondary inflammatory reactions. The other mechanism is programmed cell death, which is a protective mechanism to remove damaged cells and it does not cause massive tissue damage around the single damaged cell. Some intracellular signals, e.g. damaged DNA, are able to arrest a normal progress of the cell cycle. The cell can initiate a normal proliferation cycle after the damage has been repaired. Extensive cell death of macrophages might lead to impaired immune system and increase susceptibility to infections. Production of the inflammatory mediators (TNF-, MIP-2 and IL-6) Inflammation is a protective response against inhaled particles, microbes, pathogens and other harmful agents. Inflammatory mediators are small proteins which regulate these inflammatory processes. Tumor necrosis factor alpha (TNF- ) and macrophage inflammatory protein 2 (MIP-2) participate in responses against inhaled particles. Macrophages produce TNF- in the early phase of the inflammation to stimulate other white blood cells to produce inflammatory mediators and to increase the uptake of the particles. Furthermore, TNF- stimulates epithelial cells and recruits inflammatory cells to site of inflammation. MIP-2 functions also in recruitment of other cells. Interleukine 6 (IL-6) contributes to the initiation and extension of the inflammatory process. Chronic inflammation can lead to exacerbation of diseases or even onset of a tumor or disease.

22 22 Physicochemical and toxic properties of particulate emissions from RWC DNA damage DNA contains all the information needed in development and function of living organisms. DNA damage and increased cell proliferation might lead to development of cancer within time. Wood combustion particles contain several potential carcinogenic compounds such as polycyclic aromatic hydrocarbons (PAHs) which are able to damage DNA directly or indirectly via inflammation or oxidative stress. 3.2 MATERIALS AND METHODS Sample preparation The particles with aerodynamic diameter less than 1 µm (PM1) were collected from diluted flue gas with Dekati gravimetric impactor (DGI) in Fine Particle and Aerosol Technology Laboratory in University of Eastern Finland (Figure 1). Sample substrates from each impaction stage were washed with methanol and weighed before and after the sampling. The collected material was extracted from the substrates with methanol in a water-bath sonicator and the extracts were concentrated using a rotary evaporator. The remaining particle suspension was dispensed into glass tubes on a mass basis and the samples were dried under nitrogen flow, and stored in -20 C. For the toxicological experiments, the PM1 samples were suspended into a small amount of DMSO and sterile water. The suspension was sonicated in a water bath right before the cell exposures. Blank control substrates were collected from all the sampling campaigns and treated similarly as the other substrates Study design of toxicological analyses Toxicological analyses were performed in a time point of 24 hours and with 3-4 different particulate doses that were chosen according to previous in vitro studies in PUPO project (Jalava et al., 2010a). The mouse macrophages were exposed to particulate doses of 15, 50, 150 and 300 µg/ml. The doses vary between 7.5 and 300 µg/ml in the measurement of DNA damage in human bronchial epithelial cells according to cytotoxicity of the sample. After the exposure, acute cell death was measured from the cell suspension of macrophages with MTT test. Programmed cell death and the phases of the cell cycle were determined from the permeabilized macrophages using flow cytometric DNA content analysis. The production of the inflammatory mediators was performed later from the cell culture medium with ELISA immunoassay. Induced DNA damage was measured from the both cell lines with Comet assay. 3.3 RESULTS Cell death and other changes in the normal cell cycle All the studied particulate samples induced a dose dependent decrease in cell viability of mouse macrophages (Figure 6A). The incomplete combustion sample from the sauna stove induced more acute cell death than the other studied samples. The largest dose of the sauna stove derived particles (300 µg/ml) decreased cell viability down to 7%. The same dose of masonry heater samples sustained the cell viability levels at approximately 50%. There were more differences in measured programmed cell death between the combustion situations. However, these detected responses were quite similar as in measurements of acute cell death. The sauna stove derived sample was the most potent inducer of programmed cell

23 3. TOXICOLOGICAL RESPONSES INDUCED BY PARTICLES 23 death (Figure 6B). It initiated the programmed cell death in 22% of macrophages at a dose of 150 µg/ml, whereas the same dose from continuous combustion in a pellet boiler induced programmed cell death only in 9% of macrophages. Figure 6. A) Acute and B) programmed cell death induced by small-scale wood combustion particles at dose µg/ml in mouse macrophages. The bars represent the mean response ± SEM (standard error) Production of the inflammatory mediators (TNF-, MIP-2 and IL-6) Exposure to wood combustion particles triggered a dose-dependent production of the inflammatory mediators in mouse macrophages (Figure 7A and B). However, the doses used in this study were not optimal in all cases. Due to extensive cell death, no production of the inflammatory mediators was detected at the largest dose of sauna stove derived sample. None of the particulate samples induced production of IL-6 in mouse macrophages. In general, the wood combustion particles induced only moderate inflammatory responses compared to those detected after exposure to particles derived from urban air or traffic (Jalava et al. 2007; 2010; Kocbach et al., 2008). Furthermore, no clear differences between the inflammatory responses induced by different heating appliance samples were detected on mass dose basis DNA damage All the wood combustion particles, except those emitted from the pellet boiler, caused DNA damage in mouse macrophages (Figure 3A) and human bronchial epithelial cells (Figure 8). Overall, the DNA damage was greater in human bronchial epithelial cells, which also expressed as larger differences between the combustion situations. Human bronchial epithelial cells were more prone to genotoxic effects induced by the combustion particles than mouse macrophages, and their responses were stronger even at lowest dose of the combustion particles. In the basis of present results, the most potent inducers of DNA damage in human bronchial epithelial cells were the sauna stove derived particles and those from the firing phase of the conventional masonry heater. In contrast, the reliable analysis of macrophages exposed to the dose of 300 µg/ml of the particles emitted from the sauna stove could not be performed due to extensive cell death.

24 24 Physicochemical and toxic properties of particulate emissions from RWC Figure 7. The production of A) TNF- and B) MIP-2 presented as fold changes in mouse macrophages after exposure to wood combustion particles (doses µg/ml). The bars represent the mean response ± SEM. Control level is 1. Figure 8. DNA damage measured as Olive Tail Moment in A) mouse macrophages B) human bronchial epithelial cells after exposure to wood combustion particles (doses 50 and 150µg/ml). The bars represent the mean response ± SEM. 3.4 DISCUSSION Relative toxicological responses Tables 8 and 9 present the toxicological responses to particle dose of 150 µg/ml on mass dose basis (per mg) and the corresponding relative responses adjusted by the emission factor (per MJ). These relative responses make a link to real-life situation and indicate the healthdamaging potency of these particles in the atmosphere. The differences in toxicological responses between the combustion situations were enhanced, when the particulate mass emissions were taken into account. These relative responses indicated clearly that the most potential inducers of cell death and DNA damage were particles from incomplete combustion of wood in the sauna stove. Also the firing phase of the masonry heater was associated with the

25 3. TOXICOLOGICAL RESPONSES INDUCED BY PARTICLES 25 increased toxic activities. The sauna stove sample had also the highest potency of inducing inflammatory responses. Table 8. Cell death and production of the inflammatory mediators after exposure to particle dose of 150 µg/ml on mass dose basis (per mg) and adjusted by the emission factor (per MJ) of each studied wood combustion appliance in mouse macrophages. The value 1.0 has been set to the responses induced by particles emitted from the pellet boiler. The highest and lowest values are printed in bold. Cell death Inflammation Acute Programmed TNF- MIP-2 per mg Pellet boiler Modern masonry heater Masonry heater (cycle) Masonry heater (batch 2,3) Masonry heater (firing) Sauna stove per MJ Pellet boiler Modern masonry heater Masonry heater (cycle) Masonry heater (batch 2,3) Masonry heater (firing) Sauna stove Table 9. DNA damage after exposure to particle dose of 150µg/ml on mass dose basis (per mg) and adjusted by the emission factor (per MJ) of each studied wood combustion appliance in mouse RAW264.7 macrophage and human BEAS-2B bronchial epithelial cell lines. The value 1.0 has been set to the responses induced by particles emitted from the pellet boiler. The highest and lowest values are printed in bold. RAW BEAS-2B per mg Pellet boiler Modern masonry heater Masonry heater (cycle) Masonry heater (batch 2,3) Masonry heater (firing) Sauna stove per MJ Pellet boiler Modern masonry heater Masonry heater (cycle) Masonry heater (batch 2,3) Masonry heater (firing) Sauna stove

26 26 Physicochemical and toxic properties of particulate emissions from RWC The effect of chemical composition on particle-induced toxicological properties The particles emitted from incomplete wood combustion (e.g. the sauna stove and the firing phase of the masonry heater) were the most potent inducers of DNA damage and cell death in this study. They also contained the highest amounts of organic carbon and PAHs (Table 7). These compounds may cause immunomodulation in the cells and thus, prevent the normal inflammatory cascade. The most complete combustion processes in the pellet boiler and modern masonry heater produced particles that contained mostly inorganic ash compounds and elements. Among this material were compounds, such as metals, which in previous studies are associated with cell death and inflammation in small amounts when dominant organics are absent. Interestingly, the wood combustion particles induced quite similar inflammatory responses, although the chemical composition of the particles was significantly different.