Instrumentation and methods for PM(2.5) and ultrafine particulate matter exposure assessment

Population exposures to ambient particulate matter (PM) have recently received considerable attention due to the association between ambient particle concentrations and mortality. Findings from health studies have raised concerns about the sufficiency of the National Ambient Air Quality Standard (NAAQS) for PM in terms of the regulated level, the upper size cut of the particles, the adequacy of measuring only PM mass and the applicability of time integrated fixed site monitoring to community and personal exposures. The need for continuous monitoring of ambient PM on shorter time scales is therefore very important as it leads to substantial improvements in population exposure assessment to ambient PM. This thesis is intended to make an attempt towards development and evaluation of instrumentation for the mass concentration measurement of ambient PM for different size modes and on a continuous or semi continuous basis. A semi continuous mass monitor for the ultrafine PM measurement has been developed based on beta attenuation technology and evaluated in the laboratory and field environment. Our results show that this semi continuous monitor can reliably be used for the measurement of ultrafines in a much finer time scale of 1 to 2 hours. Progress is being made on a portable semi continuous instrumentation for the measurement of coarse, fine and ultrafine particles. Another study was directed to evaluate a continuous personal PM2.5 mass monitor that can be used for occupational health studies and personal exposure assessments. This instrument has been evaluated on a laboratory bench scale and instrument response to the particle sizes and relative humidity effects are modeled. Other than the development of instrumentation, a study was conducted to address how individual organic compounds can be used as tracers for primary source of ambient particulate matter in chemical mass balance receptor models.