particle

Indoor exposure to particles of outdoor origin constitutes an important exposure pathway. We conducted an intensive set of indoor particle measurements in an unoccupied house under differing operating conditions. Real-time measurements were conducted both indoors and outdoors, including PM2.5 nitrate, sulfate, and carbon. Because the time-scale of the fluctuations in outdoor particle concentrations and meteorological conditions are often similar to the time constant for building air exchange, a steady state concentration may never be reached.

Several studies based on analytical models and numerical simulations have shown that it is difficult to control airborne particle movements in a ventilated room. However, more knowledge and information on particle characteristics and particle movements, in combination with new numerical simulation tools, have recently made it easier to estimate particle patterns. In the present paper new information is used to evaluate the role of filtration and ventilation in the particle elimination process.

Maintenance workers expressed concern of a potential health hazard due to a strong odor from used ventilation filters during routine maintenance at a research facility. This prompted a thorough examination of the physical and chemical nature of the filters and collected particulate matter. Light and electron microscopy indicated a predominance of opaque small particles, mostly in the submicrometer range. Many were agglomerations of smaller, roughly spherical subunits, consistent with combustion aerosol.

Two new blocks of flats have been built for people with respiratory diseases. A number of points were taken into particular account during the design and construction of the buildings. For example, the project designers and builders were given training in prevention of problems with indoor air, only building materials that had been tested and found to have low emissions were used, and a supply/exhaust ventilation system and a central vacuum-cleaning system were installed.

Airborne particle size distribution depends on the type of source from which the particles originate - filtration efficiency in turn, is dependent on particle size. Thus, in order to optimise filtration efficiency, it is important to gain knowledge on both: the size distribution of particles in the air to be filtered and the relationship between filtration efficiency and particle size. In addition, assessment needs to be made about the expected concentration level of particles around the building envelope and its time variation.

Particle number concentrations and size distributions were measured in the living room of an unoccupied apartment located in a street canyon in central Copenhagen, in the street, and at a nearby urban background station. A simple dispersion model was used to calculate the particle concentrations outside a window facing the street from where most of the ventilation air was supplied. The penetration efficiencies and the deposition rates were estimated using the concentration rate balance, ignoring indoor sources.

Accurate characterization of particle concentrations indoors is critical to exposure assessments. It is estimated that indoor particle concentrations depend strongly on outdoor concentrations. For health scientists, knowledge of the factors that control the relationship of indoor particle concentrations to outdoor levels is particularly important. In this paper, we identify and evaluate sources of data for those factors that affect the transport to and concentration of outdoor particles indoors.

Disturbances from the surroundind environment and boundary conditions can influence very much the flow pattern , particles concentration and temperature distribution in a room.This report confirms the importance of working with measurements and simulations in parallel. Simulations of indoor air quality need to be validated . Guidelines on how to combine results are discussed in the paper.

Critical parameters such as the particle source location, air supply inlet design, operating table location, and lamp design are responsible for the particle distribution within the operating room, they have been investigated by means of CFD.

CFD is a suitable tool to calculate concentration in particle contaminant distribution in a room. 3 approaches are described for two types of flow problems and compared in this paper.