Partic. vol. 35 pp. 1-9 (December 2017)
doi: 10.1016/j.partic.2017.05.001

Deliberation between PM₁ and PM_2.5 as air quality indicators based on comprehensive characterization of urban aerosols in Bangkok, Thailand

Issariya Vejpongsa^a, Sirikalaya Suvachittanont^a, Natsuda Klinklan^a, Thunyapat Thongyen^b, Miklos Veres^c, Wladyslaw W. Szymanski^{a, d, *}

w.szym@univie.ac.at

Abstract

Urban ambient aerosols in the size range below 10 μm were measured and sampled for further evaluation (by Raman and Thermal-Optical analysis) of the collected material. The presented data shows that monitoring number and/or surface area concentrations besides the mass concentration provides valuable information for a meaningful assessment of the actual ambient air quality. The aim of the study was to characterize the urban aerosols using various instruments, methods, and sampling conditions, and to determine whether a split of the PM_2.5 size fraction at PM₁ may deliver a more sensible indication of the actual air quality than the current standard of monitoring PM_2.5. We found substantial differences relating to this split. PM_2.5 data frequently include particles from both mechanical and combustion processes. PM₁ measurements can be used to better distinguish particles derived from these two sources. We measured number concentrations of PM₁ with PM_2.5-1 concurrently with particle mass concentration and found that the typical average particle diameter by mass in the urban aerosols investigated was in the range of 120 nm; this corresponded well with the particle number size distributions measured in real time. Raman spectral analysis and thermal-optical evaluation of the sampled material also suggested that it would be sensible to split the measurement of the PM_2.5 fraction into PM₁ and PM_2.5-1 size fractions, especially for analysis of carbonaceous aerosol components using the DRI thermal/optical reflectance carbon analysis system

Graphical abstract

Keywords

Urban aerosol; PM-fractions; Carbonaceous particles; Raman spectroscopy; Thermal-optical analysis