Sensor Selection and Scaling Up Mobile Monitoring for High-Resolution Mapping of Community Air Quality: Design Considerations in the MOV-UP Airport Ultrafine Particle Study

Abstract

As novel environmental monitoring and exposure sensing approaches evolve, there is still the need to match the air quality concerns of communities with appropriate measurements. Designing an appropriate measurement approach for exposure studies requires identifying the sources of greatest concern, the set of pollutants that best characterize these sources, and sampling in manner that quantifies variations in concentrations in space and time. Recently, for the new Mobile Observations of Ultrafine Particles (MOV-UP) study, a sampling plan was designed to characterize ultrafine particle levels in communities near the SeaTac International Airport in Seattle, WA.Because of the need to cover a large area of approximately 250 km2 with a limited instrument and staffing budget within the timeframe of a year, a mobile monitoring approach was chosen, in which two instrumented vehicles would collect ultrafine particle measurements along local roads that transect the flight paths of the airport. Mobile monitoring would allow coverage of the large area with a relatively small number of high-end ultrafine particle counters.In addition to measuring ultrafine particle concentrations for the MOV-UP study, there was also a need to distinguish between ultrafines sourced from roadway traffic versus those from aircraft. GPS data were used to identify driving on major roadways, and were supplemented by additional measurements of ultrafine particle size and black carbon levels to help discriminate between roadway and aircraft sources. A principal component analysis (PCA) yielded multivariate eigenvalues representative of the different sources of concern. Also, relating flight patterns with wind patterns may also help to identify ultrafine particle levels attributable to aircraft.