Physical activity changes the deposited fractions of particles in the respiratory tract of adults and children

Exposure to ambient air pollution can cause a numberof health problems and may be particularly dangerous to susceptible population groups such as children. Health effects caused by air pollution are criticallydependent on both the deposited fraction (DF) of the inhaled particles and in what region of the respiratory tract the deposition takes place. With increasing physical activity, the breathing pattern is altered and the airflow in the respiratory tract increase, this affects the DF and deposition site. In this study we investigated changes in DF at increasing physical activity for three population groups: ~5 and 10 year-old children, and adults.Our results indicate that the variation in total DF with physical activity is minor, but that the DF for the UFPs increase in the AI region at higher activity levels. This is important since the removal of particles in the AI region is not effective and UFPs are believed to pose a specific health risk. Therefore, activity patterns and DF of different population groups need to be considered when estimating particle dose and evaluating health risks

Exposure and Emission Measurements During Production, Purification, and Functionalization of Arc-Discharge-Produced Multi-walled Carbon Nanotubes.

Background: The production and use of carbon nanotubes (CNTs) is rapidly growing. With increased production, there is potential that the number of occupational exposed workers will rapidly increase. Toxicological studies on rats have shown effects in the lungs, e.g. inflammation, granuloma formation, and fibrosis after repeated inhalation exposure to some forms of multi-walled CNTs (MWCNTs). Still, when it comes to health effects, it is unknown which dose metric is most relevant. Limited exposure data for CNTs exist today and no legally enforced occupational exposure limits are yet established. The aim of this work was to quantify the occupational exposures and emissions during arc discharge production, purification, and functionalization of MWCNTs. The CNT material handled typically had a mean length <5 μm. Since most of the collected airborne CNTs did not fulfil the World Health Organization fibre dimensions (79% of the counted CNT-containing particles) and since no microscopy-based method for counting of CNTs exists, we decided to count all particle that contained CNTs. To investigate correlations between the used exposure metrics, Pearson correlation coefficient was used

Characteristics of Welding Fume Aerosol Investigated in Three Swedish Workshops

Potentially high human exposures to nanometer sized airborne particles occur due to welding and other thermal processes in industrial environments. Detailed field measurements of physical and chemical particle characteristics were performed in three work-shops in Sweden. Measurements were performed both in the plume 5-20 cm above the welding point and in the background air (more than 5 m away from the nearest known particle source). Particle number and mass concentrations were measured on-line. A low pressure impactor was used for size-resolved chemical particle composition. The in-plume measurements generated the chemical signatures for different welding processes. These signatures were then used to identify contributions from various processes to the particle concentrations in different size classes. The background number and mass concentrations increased by more than an order of magnitude during intense activities in the work-shops compared to low activities during breaks