| 191. |
|
|
| 192. |
- Pagels, Joakim, et al.
(författare)
-
Characteristics of aerosol particles formed during grate combustion of moist forest residue
- 2003
-
Ingår i: Journal of Aerosol Science. - 0021-8502. ; 34:8, s. 1043-1059
-
Tidskriftsartikel (refereegranskat)abstract
- The characteristics of aerosol particles formed during combustion of moist forest residue were studied as a function of load in a I MW moving grate boiler and at almost full load in a similar larger 6 MW boiler. The coarse (1 mum < d(ae) < 10 mum) particle number and mass concentration increased by more than one order of magnitude and the fine particle mean diameter, total volume and mass decreased when the load was increased from 50% to 75%. The combined effects led to an increase in PM10 with increasing load. The number and mass concentration and the size distribution were similar in the two boilers when operated at high load. The dominant elements (Z > 12) were K, S and Cl in the fine mode and Ca, K and S in the coarse mode. The dominant ions in the fine mode were K+, SO42- and CO32-. The fine mode particles had hygroscopic growth factors of around 1.65 at RH=90%, with a deliquescence point at a relative humidity between 30% and 60%. It was assessed that K2CO3 is responsible for the low deliquescence point. Fine mode particles of a given dry diameter had similar chemical composition. (C) 2003 Elsevier Ltd. All rights reserved.
|
|
| 193. |
- Pagels, Joakim, et al.
(författare)
-
Chemical composition and mass emission factors of candle smoke particles
- 2009
-
Ingår i: Journal of Aerosol Science. - : Elsevier BV. - 0021-8502. ; 40:3, s. 193-208
-
Tidskriftsartikel (refereegranskat)abstract
- The aim of this study is to investigate the physical and chemical properties of particle emissions from candle burning in indoor air. Two representative types of tapered candies were studied during steady burn, sooting burn and smouldering (upon extinction) under controlled conditions in a walk-in stainless steel chamber. Steady burn emits relatively high number emissions of ultrafine particles dominated by either phosphates or alkali nitrates. The likely source of these particles is flame retardant additives to the wick. Sooting burn in addition emits larger particles mainly consisting of agglomerated elemental carbon. This burning mode is associated with the highest mass emission factors. Particles emitted during smouldering upon extinction are dominated by organic matter. A mass closure was illustrated for the total mass concentration, the summed mass concentration from chemical analysis and the size-integrated mass concentration assessed from number distribution measurements using empirically determined effective densities for the three particle types. (C) 2008 Published by Elsevier Ltd.
|
|
| 194. |
- Pagels, Joakim, et al.
(författare)
-
Deposition of particle-attached radon progeny in the respiratory tract - an experimental study of children and adults in home environments
- 1999
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- A method to study total deposition of aerosol attached radon progeny in children and adults have been validated and used in home environments. Two persons, one child and one adult are tested simultaneously, thus inhaling from the same aerosol and allowing for a direct comparison. The aim of the study was to increase the knowledge of the lung deposition and thereby the knowledge of the radiation dose from indoor radon. In the study 13 children (ages 4-13 years) and 11 adults were tested in their home environments (five dwellings with elevated radon levels 200 - 600 Bq/m3). Two different aerosols were used: the background aerosol particles when no strong indoor sources were present and the relatively small particles from normal candle burning (activity median diameters (AMD) roughly 200 and 50 nm respectively). An enhanced deposition was found for the children compared to the adults for the smaller particles (mean deposition 38 and 31%), while for the larger background particles no difference was found (31% deposition for both groups). Differences between the deposition of the different short lived radon daughters was found. This was infered to be explained as an ageing effect. In one of the dwellings measurements were performed to estimate hygroscopic growth of the particles upon inhalation. Growth factors between 1 and 4.5 was found. When comparing the results with a stochastic lung deposition model (hygroscopic growth taken into account) reasonable good agreement was found for the smaller particles (experiments 31% and model 26%), while for the larger background particles a roughly doubled deposition was found (experiments 31% and model 15%). A comparison of the deposition when breathing through mouth and nose has also been conducted. This part of the study with adults only was performed in a radon exposure chamber. Relatively large (AMD =500 nm) hydrophobic particles from flickering candle burning (black smoke) were used. Mean depositions of 11 and 17% were found when breathing through mouth and nose respectively. Good agreement was found when comparing with the stochastic model.
|
|
| 195. |
- Pagels, Joakim
(författare)
-
Fine and Ultrafine Particles from Combustion Sources - Investigations with In-situ Techniques
- 2005
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Fine airborne particles are associated with adverse health effects in the human population. The aim of this research was to develop and evaluate methods for in-situ characterisation of fine and ultrafine particles and to determine their deposition in the human airways. The aim was also to increase knowledge about health and environmentally relevant properties of aerosols from biomass combustion and selected indoor sources. The methods include instrumental techniques such as Scanning Mobility Particle Sizer (SMPS), Electrical Low-Pressure Impactor (ELPI), Aerodynamic Particle Sizer (APS) and Tandem Differential Mobility Analysers (TDMA) based on volatility and hygroscopic growth. Filter samplers and impactors were used for collecting particles on substrates for subsequent chemical analysis. Emissions from local district heating plants (0.5-12 MW), based on moving grate combustion of woody fuels, were sampled with a dilution system and characterised. Particles from the indoor sources of cigarettes, incense and candles were examined in the laboratory by using an airtight 22 m3 stainless steel chamber. A set-up to determine respiratory deposition in humans was constructed. It was automatised and uses an electrical mobility spectrometer with an improved inversion algorithm to perform fast measurements of particles of different sizes in the inhaled and exhaled air. It was evaluated on human test-persons. The investigated biomass combustion sources emit high concentrations of fine and ultrafine particles. The chemical composition is dominated by KCl and K2SO4; Zn, Cd and Pb were also quantified. Elemental carbon was identified in particles larger than 150 nm during periods of incomplete combustion. The particle concentration depends on the fuel ash content and the combustion efficiency. The aerosol is essentially internally mixed with hygroscopic growth factors significantly higher than reported for diesel exhaust and environmental tobacco smoke. The particles restructure from agglomerates to a more compact shape upon first exposure to moderately high relative humidity. This results in an increase in effective density and fractal dimension. Hygroscopic growth of these particles reduces the respiratory dose by a factor of 3-4 compared to hydrophobic particles of the same size. The biomass combustion particles mainly consist of soluble ash components and need to be treated differently in future health effect assessments compared to particles from incomplete combustion, e.g. from diesel engines, wood stoves and cigarette smoke. Sidestream cigarette and incense smoke are well internally mixed aerosols dominated by organic compounds. Each particle consists of components with a relatively wide range in vapour pressure. The volatile fraction decreases at lower particle concentrations in the chamber and upon ageing, which is attributed to different degrees of evaporation from the particle to the gas phase. Four different particle types were identified in emissions from candles. The feasibility of the ELPI and the APS to assess mass size distributions was investigated. It was found that the measurement quality is dependent on the size distribution of the aerosol. The set-up for respiratory deposition has low inherent particle losses. Determinations of precision, accuracy and sensitivity show that it can be used for field measurements in typical urban and indoor environments. Methods for characterisation of aerosols containing fine and ultrafine particles have been developed, evaluated and applied. The results can be used to improve exposure assessments in toxicological and epidemiological studies and for risk assessments. Papers included in the thesis I. Pagels J., Strand M., Rissler J., Szpila A., Gudmundsson A., Bohgard M., Lillieblad L., Sanati M. and Swietlicki E. (2003) Characteristics of Aerosol Particles Formed During Grate Combustion of Moist Forest Residue, Journal of Aerosol Science 34, 1043-1059 II. Wierzbicka A., Lillieblad L., Pagels J., Strand M., Gudmundsson A., Gharibi A., Swietlicki E., Sanati M. and Bohgard M. (2005) Particle Emissions from District Heating Units Operating on Three Commonly Used Biofuels, Atmospheric Environment 39, 139-150 III. Rissler J., Pagels J., Swietlicki E., Wierzbicka A., Strand M., Lillieblad L., Sanati M. and Bohgard M. (2005) Hygroscopic Behaviour of Aerosol Particles Emitted from Biomass Fired Grate Boilers, Submitted IV. Pagels J., Gudmundsson A., Gustavsson E., Asking L. and Bohgard M. (2005) Evaluation of Aerodynamic Particle Sizer and Electrical Low-Pressure Impactor for Unimodal and Bimodal Mass-Weighted Size Distributions, Submitted V. Pagels J., Löndahl J., Zhou J., Bohgard M. and Swietlicki E. (2005) A set-up for Field Studies of Respiratory Deposition in Humans, Manuscript
|
|
| 196. |
|
|
| 197. |
|
|
| 198. |
- Pagels, Joakim, et al.
(författare)
-
Fine-particle emissions from solid biofuel combustion studied with single-particle mass spectrometry: Identification of markers for organics, soot, and ash components
- 2013
-
Ingår i: Journal of Geophysical Research: Atmospheres. - 2169-8996. ; 118:2, s. 859-870
-
Tidskriftsartikel (refereegranskat)abstract
- The effects of combustion phase and fuel on smoke particle emissions from a wood stove operated with three different wood fuels and from a corn stove were investigated. A single-particle mass spectrometer (aerosol time of flight mass spectrometer (ATOFMS)) was used for time-and size-resolved chemical signatures and a scanning mobility particle sizer (SMPS) was used for online mobility size distributions. Markers of particle phase organics and elemental carbon, PM1.5, and CO emissions were strongly reduced for the corn stove compared to the wood stove. This is because the more controlled fuel and air supply in the corn stove result in more complete combustion. NOx emissions and particle phase phosphates showed the opposite trend. Marker ions and particle types associated with soot and alkali salts such as potassium chloride and potassium sulfates dominated during flaming combustion and were correlated with increased exhaust temperatures and reduced CO emissions. Marker ions of hydrocarbons and oxidized organics as well as a particle cluster type with a strong organic signature were associated with reduced combustion temperature and increased CO levels, observed during start up from cold stove, addition of fuel, and combustion with reduced air supply. Two different particle types were identified in corn experiments when particles were classified according to mobility before they were measured with the ATOFMS. "Less massive" particles contained mostly ash and soot and had vacuum aerodynamic diameters that were nearly independent of mobility diameter. "More massive" particles had aerodynamic diameters that increased linearly with mobility diameter, indicating approximately spherical shapes, and were hypothesized to consist of organics.
|
|
| 199. |
|
|
| 200. |
|
|
