The flow field in the TSI aerodynamic particle sizer (APS) has been modeled numerically and particle trajectories have been calculated. The effects of varying physical parameters such as beam location, beam separation, and nozzle separation were studied. Values of these parameters were determined for a particular APS by comparing the calculated particle transit times with measured ones for polystyrene latex and polyvinyl toluene aerosols. This configuration was used to determine the effect of particle density on APS response and to generate correction factors permitting actual aerodynamic diameter to be determined from indicated aerodynamic diameter when particle density is known. Sensitivity studies show that the calculated correction factors will apply to any TSI APS manufactured and operated within the manufacturer's specifications.
The objectives of the present work were to investigate techniques for the continuous, qualitative monitoring of VOCs and to see how VOC levels were influenced by normal household activities. Three different methods were investigated to measure the VOC levels: infrared spectroscopy, photoionization detection, and gas chromatographic analysis of absorbent tube samples. Results were presented that related changes in levels of VOCs to various human activities commonly occurring in residences, and data were presented that indicated activities such as cooking, arts and crafts, cleaning floors, and painting contributed to short-term increases in VOC levels. VOC levels were diminished by turning on the air conditioner. Results on the effect of humidity on VOCs, both in homes and controlled chambers, were reported.
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