10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
Abstract View
Field Calibration of 50 AQMESH Air Quality Sensors
Jacob Swanson, TRES WUERFFEL, Monika Vadali, Minnesota State University, Mankato
Abstract Number: 979 Working Group: Low-Cost and Portable Sensors
Abstract Understanding small-scale differences in air pollution is essential to minimizing exposure to harmful air pollutants, particularly among vulnerable communities such as communities of concentrated race or poverty. Traditional air monitoring methods are cost-prohibitive to deploy at the level of coverage needed to investigate this important question. However, low-cost sensors that measure air pollutants of concern are now available. The overall objective of this work is to deploy an innovative monitoring approach using low-cost air sensor technology to increase understanding of the variability of air pollutants in urban areas. Data will be used to 1) evaluate pollution reduction opportunities, and to compare with population vulnerability and health outcome data, 2) evaluate the use of new technologies in air pollution sensors as an innovative, cost-effective monitoring strategy, and 3) expand the availability of ambient air quality data to inform decisions, especially regarding public health improvement opportunities.
A network of 50 air quality sensors has been deployed in the St. Paul and Minneapolis neighborhoods, with approximately one sensor per zip code. The “Twin Cities” of Minnesota is a major, seven-county metropolitan area comprising about 3.5 million people. The first step of this deployment was field calibration of the 50 sensors. The air quality sensors were AQMESH pods, version 4.0. These sensors cost about $10,000 each or about $1,000 per metric, which we believe to be in the range of “low-cost” measurement technology. AQMESH measures fine particles (PM1.0, PM2.5, and PM10) and five gases at ppb levels. Gases measured include ozone (O3), nitrogen oxides (NO and NO2), sulfur dioxide (SO2) and carbon monoxide (CO). Additionally, the sensors measure ambient temperature and relative humidity. Raw data collected from the sensors are centrally processed for cross-sensitivity and other factors that influence response using algorithms proprietary to the manufacturer. All sensors were initially deployed together and contiguous to a Minnesota Pollution Control Agency (MPCA) federal reference method (FRM) monitoring station for “field calibration.” Data from sensors was collected for three weeks during the winter. This presentation reports on 1) the efficacy and limitations of the initial, “factory” calibration settings, 2) inter-sensor comparisons, and 3) comparisons and validation with FRM methods for both gases and particles. Overall, for most gases, the factory calibration provided a “usable” calibration for cases where FRM instruments would not be available. Subsequent calibration with FRM data has the potential to improve accuracy. We conclude by discussing long-term strategies to monitor and address reliability, sensor drift, additional field calibration once the sensors are individually deployed, and the possible degradation of sensor elements due to Minnesota-specific prevailing atmospheric conditions.