Heavy Metal Analysis

Personal Environmental Monitor (PEM Sampler)

The Personal Environmental Monitors (PEM^TM, Model 200) used were made by MSP Corporation (Minneapolis, MN, USA). This miniature active sampler is also operated by the principle of inertial impaction, using a single stage impactor with an after-filter. The impactor used in the PEM^TM sampler consists of 10 round nozzles located in a circle near the outer edge of the cover and a doughnut-shaped impaction surface. The sampler can be operated at an evacuating volumetric flow rate of 2.0, 4.0 or 10.0 L/min at ambient conditions, each with an impactor at a PM cut point of either 10��m or 2.5��m aerodynamic diameter. The mass collected on the pre-weighed filter is then measured by the gravimetric method in the laboratory. The PEM^TM sampler is not a reference or equivalent method device. The flow rates used are much less than those used in reference method devices and the sampler is not equipped with a mean of flow rate measurement or a timing control device. However, it was claimed that results for PM10 were comparable to those obtained with the reference methods (Bukley, et al., 1991; Lioy, et al., 1988). The PEM^TM samplers with the evacuating volumetric flow rate of 10 L/min with either PM₁₀ or PM_2.5 inlet impactors were used in the pilot study to collect the outdoor (outside the residence house) and the ambient (at the local ambient air quality monitoring stations) PM samples. The PEM^TM samplers with the evacuating volumetric flow rate of 4 L/min with either PM₁₀ or PM_2.5 inlet impactors were used to collect the personal PM exposure samples.