Investigation of the physical and chemical characteristics of ambient coarse particulate matter in indoor and outdoor environments

Atmospheric coarse particles have been studied thoroughly but have recently come back into the spotlight due to a combination of bioterroristic threats, new technologic discoveries, and health effects studies. The longtime standard for sampling and measuring coarse PM, the 24-hour time-integrated filter sample, has been questioned for accuracy due to possible measurement error. This thesis is intended to alleviate the paucity of information on both the short-term variation of ambient coarse PM and to what extent humans are exposed to it. An indoor versus outdoor study in a desert location was conducted to demonstrate that even in environments with high outdoor coarse PM concentrations, indoor home exposure to coarse particles is almost entirely influenced by indoor sources and not penetration of outdoor coarse PM. Due to the relatively low ambient levels of coarse PM in many locations, a coarse particle concentrator was developed and evaluated. This device can concentrate ambient levels up to 30 times for in vivo exposure studies or sample collections over much shorter time intervals. Another device designed to measure coarse PM over short time intervals is also presented. The Continuous Coarse Particle Monitor measures real-time coarse particle mass concentrations and thus can be used for simple monitoring or detailed human or animal exposure studies. A PM10 size-selective inlet was modified to operate at 50 LPM, the designed flow rate of the1 Continuous Coarse Particle Monitor. This inlet was tested in a laboratory wind tunnel and an outdoor field location and found to have a very sharp cutpoint near 9 mum. The final chapter of this work is dedicated to the overlap between the ambient coarse and fine PM modes. A study was conducted to determine the effect of the tail of the coarse PM mode on the intermodal size range, or particles between 1 and 2.5 mum. Results indicate that in Los Angeles, intermodal PM is very similar to PM1 and shows nearly no correlation with coarse PM.