Health-related aerosol particle studies, respiratory tract deposition and indoor source identification

Research output: ThesisLicentiate Thesis

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Abstract

Aerosol particles have, since Classical Antiquity, been linked to adverse effects on human health. It is estimated that the particles in urban air pollution causes 100 000 deaths in Europe each year, whereof 5 000 in Sweden. These figures do not include the outcomes of indoor sources or smoking, which shortens the lives of millions of people worldwide. Many studies indicate that fine particles (<2.5 μm) are to be more toxic than larger ones. Especially the ultrafine particles (<0.1 μm), typically originating from combustion sources, have been of much concern. Part of the reason could be their high probability to deposit deep into the lung once inhaled. A novel method has been developed for determination of fine and ultrafine particle deposition in the respiratory tract. It is designed to be used on larger groups of human subjects in exposure studies and in typical ambient and indoor environments. The method is demonstrated to have a precision in the determined deposition fraction (DF) of 0.02–0.08 and to be sensitive enough to quantify differences between breathing patterns and between hygroscopic and hydrophobic aerosols. The results for hydrophobic particles are in agreement with the well-established ICRP 66 model. The developed instrument was used to investigate the influence of hygroscopicity (the ability to grow by uptake of water), exercise level,
gender and intersubject variability on size-dependent deposition of fine and ultrafine particles (12-320 nm) during spontaneous breathing. DF was measured for 29 healthy adults (20 men, 9 women) in four exposure situations; rest and light exercise with both hydrophobic (Di-Ethyl-Hexyl-Sebacate) and hygroscopic (NaCl) particles. DF was 2-4 times higher for the hydrophobic ultrafine particles than for the hygroscopic. DF of hygroscopic ultrafine particles could be estimated by calculating their equilibrium size at 99.5% relative humidity. The differences in average DF due to exercise level and gender were essentially insignificant, but the minute ventilation was 4-fold higher during exercise and 18%-46% higher for the males. Consequently the deposited dose of particles was 4-fold higher during exercise and considerably increased for the male subjects. Some individuals generally had a high DF in all four sessions.
To assist the work for healthy indoor environments, a methodology for identifying sources to particles larger than 0.5 μm was designed and applied in a study of three houses in southern Sweden. The methodology includes (1) visual inspection in order to identify deposited particles and potential sources, (2) measurement of airborne particles at different positions in a building with simultaneous logging of activities and (3) isolation of potential sources in a test chamber for controlled characterizations of the generated particles. The results show that source identification is facilitated by knowledge of concentration variations between different rooms, real-time measurements together with activity reports and information on particle characteristics that are comparable with results from laboratory simulations. Major particle emissions from textile handling, likely due to detergent zeolite residues, were found in the studied houses.
Original languageEnglish
QualificationLicentiate
Awarding Institution
  • Nuclear physics
Supervisors/Advisors
  • Erik, Swietlicki, Supervisor, External person
Publisher
Publication statusPublished - 2006

Bibliographical note

The information about affiliations in this record was updated in December 2015.
The record was previously connected to the following departments: Nuclear Physics (Faculty of Technology) (011013007)

Subject classification (UKÄ)

  • Subatomic Physics

Keywords

  • aerosol particle
  • health
  • ultrafine particles
  • nanoparticle
  • deposition
  • respiratory tract
  • Fysicumarkivet A:000

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