| Autor: |
Feinberg SN; Oak Ridge Institute for Science and Education, Oak Ridge, TN 37830.; U.S Environmental Protection Agency (EPA), Office of Research and Development, Research Triangle Park, NC 27711., Williams R; U.S Environmental Protection Agency (EPA), Office of Research and Development, Research Triangle Park, NC 27711., Hagler G; U.S Environmental Protection Agency (EPA), Office of Research and Development, Research Triangle Park, NC 27711., Low J; Shelby County Health Department, Memphis, TN 38105., Smith L; Shelby County Health Department, Memphis, TN 38105., Brown R; U.S. EPA Region 4, Atlanta, GA 30303., Garver D; U.S. EPA Region 4, Atlanta, GA 30303., Davis M; U.S. EPA Region 7, Lenexa, KS 66219., Morton M; U.S. EPA Region 6, Dallas, TX 75202., Schaefer J; U.S. EPA OLEM, Edison, NJ 08837., Campbell J; General Dynamics Information Technology; Edison, NJ 08837. |
| Abstrakt: |
Traditional air monitoring approaches using regulatory monitors have historically been used to assess regional-scale trends in air pollutants across large geographical areas. Recent advances in air pollution sensor technologies could provide additional information about nearby sources, support the siting of regulatory monitoring stations, and improve our knowledge of finer-scale spatiotemporal variation of ambient air pollutants and their associated health effects. Sensors are now being developed that are much smaller and lower cost than traditional ambient air monitoring systems and are capable of being deployed as a network to provide greater coverage of a given area. The CitySpace project conducted by the US EPA and the Shelby County Health Department included the deployment of a network of 17 sensor pods using Alphasense OPC-N2 particulate matter (PM) sensors integrated with meteorological sensors in Memphis, TN for six months. Sensor pods were collocated with a federal equivalent method (FEM) tapered element oscillating microbalance (TEOM) monitor both before and after the primary study period. Six of the sensor pods were found to meet the data quality objective (DQO) of coefficient of determination (R 2 ) greater than 0.5 when collocated with the TEOM. Seven pods were decommissioned before the end of the study due to mechanical failure. The six pods meeting the DQO were used to examine the spatiotemporal variability of fine PM (PM 2.5 ) across the Memphis area. One site was found to have higher relative PM 2.5 concentrations when compared to the other sites in the network. The 1-min data from this sensor pod were evaluated to quantify the regional urban background and local-scale contributions to PM 2.5 at that monitoring location. This method found that approximately 20% of the PM 2.5 was attributed to local sources at this location, compared to 9% at a local regulatory monitoring site. Additionally, the 1-min data were combined with 1-min wind speed and wind direction data to examine potential sources in the area using the nonparametric trajectory analysis (NTA) technique. This method geographically identified local source areas that contributed to the measured concentrations at the high reading sensor location throughout the course of the study. |
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