|Particulate Monitoring||Creating the Context: Research Methodology|
Results of Study
Results of Study
Purpose: Measure the quantity of particulates present in the air by collecting the particulates on a filter. The mass of particles collected on the filter, combined with the amount of air passed through the filter, will be used to determine the concentration of particulates in the air during the sampling period.
I. Filter Analysis: All filter analyses will be conducted in a laboratory room controlled for temperature, humidity, and air flow currents. The balance used for the analysis will be capable of measuring to one (1) microgram. The balance will be calibrated before and after the analysis of each set of filters (pre-sampling and post-sampling) described below.
A. Inspection: All filters will be visually inspected for defects before initial weighing. Any filter found defective will be rejected. Example defects include, but are not limited to, the following:
B. Pre-sampling Preparation: Unexposed filters will be placed in a desiccator at least 24 hours prior to sampling. The filters will be removed from the desiccator no more than one (1) day prior to use in the field. When outside the desiccator, the filters will be stored in a protective cassette. Each filter will have a unique ID number consisting of the sampling day and inlet used. The ID number will be placed on the filters protective cassette.
C. Post-sampling Analysis: Exposed filters will be placed in a desiccator no more than 24 hours after collection in the field. When outside the desiccator, the filters will be stored in a protective cassette. Each filter will have a unique ID number consisting of the sampling day and inlet used. The ID number will be placed on the filters protective cassette.
D. Gravimetric Analysis (Cahn Model C-33 balance): It is suggested that the balance will be located in a room controlled for temperature, humidity, and air flow currents. If this is not possible, weighing error only rises slightly. Calibration with a NIST-traceable 200 mg weight will occur prior to filter analysis, and after every 20 samples analyzed. The calibration weight will be stored in a separate container in the temperature controlled lab, and dedicated teflon coated forceps will be used for handling to avoid contamination. If calibration error is greater than 2%, the balance will be adjusted and all previously analyzed samples will be re-weighed. The balance will also be equipped with static de-ionizing units, one centered in the balance, and one mounted near the balance, to eliminate sample artifacts from static charges. The balance will be turned on and allowed to warm up for a minimum of 30 minutes before use to attain stability.
II. Sample Storage: All PM samples will be stored in a dessicator to reduce the presence of water vapor on the filter, affecting it's weight from humidity effects. The dessicators will be stored in a temperature controlled room to reduce filter artifacts from volatilization of particulate constituents. After analysis, each filter will be placed in a separate cassette and stored for a period no less than six (6) months in the temperature controlled room.
III Sampling Procedure: The following procedures will be followed in the field to collect exposed filters and install unexposed filters.
IV. Sampler Maintenance
A. Impactor: After every seventh sample, the impaction stage will be cleaned and regreased in a well ventilated area using the following procedures.
B. Battery: The battery packs will be exchanged and recharged after each sampling day. Each battery will be recharged until the charging indicator light turns off. The AA batteries for the timers will be replaced every six (6) months.
|1999, KanCRN Collaborative Research Network|