Master of Engineering (ME)
Civil and Environmental Engineering
First Committee Member
Hualiang (Harry) Teng
Number of Pages
The Las Vegas area has been designated by the U.S. EPA as a serious PM 10 non-attainment area. To monitor PM10 in this area, dust data have been collected quarterly using the AP-42 method. According to this method, the number of composite sample sizes (the number of sample sites) needs to be determined first. In the actual dust data collection at each of these sample sites, a procedure with the specifications of the number and locations of incremental samples (plots) and their sizes (i.e., length) has to be followed. Apparently, there has been no rule existing that can be used to determine the composite sample size. In addition, it is unknown whether the required number of plots and their sizes are validated based on real data; Due to the availability of dust emission data collected using mobile sampling technologies, which are viewed as being close to actual continuous dust emission data over a roadway segment, this study investigates the optimal number of sample sites and number of plots and their sizes that can be used for the AP-42 method. To determine the number of sample sites, the optimal allocation sampling method is adopted. By using this method, the variance of emission estimated based on samples can be minimized for a fixed budget. The issue with validating the number of plots and their sizes for the AP-42 method is investigated by using the Monte Carlo simulation method. In the simulation, the layouts of plots are emulated following the AP-42 method. The difference between the estimated emission factor based on the emulated AP-42 method and the true emission factor are compared. Patterns for the difference between the estimated and true emission factors versus the number and size of plots are observed. These observed patterns are used to derive the thresholds of the number and size of plots for the AP-42 method; The results from the optimal allocation method indicate that most sample sites should be allocated to the local roads because the variance of emission and proportion of roadway segments of this roadway classification are significantly higher than most of other roadway classifications. This conclusion may lead to the development of more cost effective sampling approaches. The results from the Monte Carlo simulation method imply that clear patterns of improved estimation of emission factors versus the number and size of plots can be observed only for three roadway classifications, not for other classifications. This result may indicate that the AP-42 method may not be applicable to some roadway classifications, and thus a different data collection method, such as the mobile sampling technologies, may be necessary.
Investigation; Methods; Sampling
University of Nevada, Las Vegas
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Chen, Yanjie, "Investigation on the AP-42 sampling method" (2007). UNLV Retrospective Theses & Dissertations. 2157.