| 1. |
|
|
| 2. |
- Wierzbicka, Aneta, et al.
(författare)
-
Detailed diesel exhaust characteristics including particle surface area and lung deposited dose for better understanding of health effects in human chamber exposure studies
- 2014
-
Ingår i: Atmospheric Environment. - : Elsevier BV. - 1352-2310. ; 86, s. 212-219
-
Tidskriftsartikel (refereegranskat)abstract
- Several diesel exhaust (DE) characteristics, comprising both particle and gas phase, recognized as important when linking with health effects, are not reported in human chamber exposure studies. In order to understand effects of DE on humans there is a need for better characterization of DE when performing exposure studies. The aim of this study was to determine and quantify detailed DE characteristics during human chamber exposure. Additionally to compare to reported DE properties in conducted human exposures. A wide battery of particle and gas phase measurement techniques have been used to provide detailed DE characteristics including the DE particles (DEP) surface area, fraction and dose deposited in the lungs, chemical composition of both particle and gas phase such as NO, NO2, CO, CO2, volatile organic compounds (including aldehydes, benzene, toluene) and polycyclic aromatic hydrocarbons (PAHs). Eyes, nose and throat irritation effects were determined. Exposure conditions with PM1 (<1 mu m) mass concentration 280 mu g m(-3), number concentration 4 x 10(5) cm(-3) and elemental to total carbon fraction of 82% were generated from a diesel vehicle at idling. When estimating the lung deposited dose it was found that using the size dependent effective density (in contrast to assuming unity density) reduced the estimated respiratory dose by 132% by mass. Accounting for agglomerated structure of DEP prevented underestimation of lung deposited dose by surface area by 37% in comparison to assuming spherical particles. Comparison of DE characteristics reported in conducted chamber exposures showed that DE properties vary to a great extent under the same DEP mass concentration and engine load. This highlights the need for detailed and standardized approach for measuring and reporting of DE properties. Eyes irritation effects, most probably caused by aldehydes in the gas phase, as well as nose irritation were observed at exposure levels below current occupational exposure limit values given for exhaust fumes. Reporting detailed DE characteristics that include DEP properties (such as mass and number concentration, size resolved information, surface area, chemical composition, lung deposited dose by number, mass and surface) and detailed gas phase including components known for their carcinogenic and irritation effect (e.g. aldehydes, benzene, PAHs) can help in determination of key parameters responsible for observed health effects and comparison of chamber exposure studies. (C) 2013 The Authors. Published by Elsevier Ltd. All rights reserved.
|
|
| 3. |
|
|
| 4. |
|
|
| 5. |
|
|
| 6. |
|
|
| 7. |
|
|
| 8. |
- Isaxon, Christina, et al.
(författare)
-
Realistic indoor nano-aerosols for a human exposure facility
- 2013
-
Ingår i: Journal of Aerosol Science. - : Elsevier BV. - 0021-8502. ; 60, s. 55-66
-
Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to achieve realistic levels of two different types of aerosols commonly abundant in indoor environments in an experimental chamber intended for human exposure studies and aerosol characterization. The aerosols chosen were particles from candle lights (in particle number dominated by inorganic water soluble particles) and from ozone-terpene reactions (organic particles). The aerosol generation and characterization system consisted of a controlled air tight stainless steel 22 m(3) chamber, to which the generation set-ups were connected. No air could enter or leave the chamber except through a conditioning system by which temperature, relative humidity and air exchange rate could be controlled. Candle smoke aerosol was generated from ten candles burning in a 1.33 m(3) glass and stainless steel chamber. The aerosol was diluted by clean air from the conditioning system before entering the chamber. Terpene vapor was generated by passing pure nitrogen through a glass bottle containing limonene oil. Ozone was generated by a spark discharge using pure O-2, and was added to the ventilation air flow downstream the inlet for terpene vapors and upstream the inlet to the chamber. Both aerosols were characterized with respect to number and mass concentrations, size distribution and chemical composition. Particle number concentration in the size range 10-650 nm could be varied from <10 cm(-3) to more than 900,000 cm(-3) (for candle smoke) or to more than 30,000 cm(-3) (for particles formed in a 160 ppb terpene/40 ppb ozone mixture). Furthermore, the set-ups were evaluated by, for each source, repeating the generation at six three-hour long events. For both aerosols repeatable generations at pre-determined concentration levels, that were stable over time, could be achieved. The results show that realistic concentrations of aerosols from real-world environments could be reproduced in a well-controlled manner and that this set-up could be used both for aerosol characterization and for human exposures. (C) 2013 Elsevier Ltd. All rights reserved.
|
|
| 9. |
|
|
| 10. |
|
|
