Cite abstract as Author(s) (2017), Title, European Aerosol Conference 2017, Zurich, Abstract T303N4b1
Field comparison of instruments for measurement of air pollutants F. Borghi1, A. Spinazzè1, G. Fanti1, L. Del Buono1, D. Campagnolo1, S. Rovelli1, A. Cattaneo1, D.M. Cavallo1 1
Department of Science and High Technology, University of Insubria, Como, 22100, Italy Keywords: PM concentration, gravimetric analysis, intercomparison, direct reading instrument Presenting author email:
[email protected]
It is well known that particulate matter (PM) can cause different adverse effects on human health (Brook et al., 2010). Recently, scientific attention has moved towards PM and ultrafine particles (UFP) exposure in urban population, also highlighting the inadequacy of current air quality monitor approaches, due to limitations regarding these kind of stations (such as poor spatial and temporal resolution). Different kind of monitoring instruments have yet to be evaluated, especially on field. The aim of this study was to compare the use of co-located real-time devices and gravimetric samplers to measure UFP and size-fractionated PM mass concentrations. Paired direct-reading devices and gravimetric samplers were used to measure different PM fraction (Table 1) during N = 16 monitoring session, under different meteorological scenarios. The monitoring campaign were performed during the winter period, in an urban background station placed in Como (Northern Italy). In order to acquire several meteorological data, an external and co-located weather station was also used. UFP and PM concentrations measurement were analyzed using linear regression analysis, separately for each PM fraction; the performance of instruments were tested evaluating linear regression outcomes following criteria defined by Watson et al. (1998). Table 1. Instrument and related PM size-fraction used in field campaign (Pho: Photometer; PCIS: Personal Cascade Impactor Samplers; CPC: condensation Particle counter; DSC: miniaturized diffusion charger).
Instrument DSC CPC Pho#1 Pho#2 Pho#3
Direct Reading PM fraction UFP PM1, PM2.5, PM5, PM10, TSP PM1, PM2.5, PM4, PM10, TSP PM2.5 Filter-based
Instrument Harvard Impactor PCIS PCIS-modified Pho#3 (gravimetric)
PM fraction PM2.5 (PM0.25; PM0.5) PM1, PM2.5, PM10 PM2.5, PM10 PM2.5
Results showed that the UFP concentrations measured using CPC were overestimated compared with the DSC, showing an absolute deviation that appeared to increase with the UFP concentration. Although these two devices
could be classified as comparable, relevant differences in the performance were observed. Regarding measurement of size fractionated PM, the comparison of different direct-reading devices generally indicated an overestimation of two of the tested instruments, with respect to the third one, used as reference. However, the comparison of light-scattering devices with filter-based samplers indicated that direct-reading devices tend both to over-estimate or under-estimate the mean PM concentrations with respect to the corresponding gravimetric analysis. Besides, the comparison of different filter-based samplers showed that the observed over-estimation error increased with increasing PM concentration levels. However, the good level of agreement between the investigated methods allowed them to be classified as comparable, although they cannot be characterized as having reciprocal predictability. Among the considered meteorological parameters, only ambient relative humidity was correlated with the absolute error resulting from the comparison of directreading vs. filter-based techniques, as well as among different filter-based samplers for the same PM fraction. In conclusion, despite a general good level of comparability, relevant absolute errors were identified among different measurement and sampling techniques, which outlines the need of standardized protocols and harmonized performance evaluation criteria for existing devices, in order to ensure the obtaining of accurate results. Brook, R. D., Rajagopalan, S., Pope, C.A., Brook, J. R., Bhatnagar, A., Diez-Roux, A. V. et al. (2010) Circulation 121, 2331-2378. Watson, JC., Chow, JC. And Moosmuller, H. (1998) Guidance for using continuous monitoring in PM2.5 monitoring networks. U.S. Environmental Protection Agency, Office of Air Quality Planning and Standards Research Triangle Park, NC 27711. EPA-454/R-98-012, 1998.
