PMID- 30308807 OWN - NLM STAT- MEDLINE DCOM- 20181109 LR - 20181202 IS - 1879-1026 (Electronic) IS - 0048-9697 (Linking) VI - 650 IP - Pt 1 DP - 2019 Feb 10 TI - Airborne particles in the city center of Kuala Lumpur: Origin, potential driving factors, and deposition flux in human respiratory airways. PG - 1195-1206 LID - S0048-9697(18)33510-1 [pii] LID - 10.1016/j.scitotenv.2018.09.072 [doi] AB - Equatorial warming conditions in urban areas can influence the particle number concentrations (PNCs), but studies assessing such factors are limited. The aim of this study was to evaluate the level of size-resolved PNCs, their potential deposition rate in the human respiratory system, and probable local and transboundary inputs of PNCs in Kuala Lumpur. Particle size distributions of a 0.34 to 9.02 mum optical-equivalent size range were monitored at a frequency of 60 s between December 2016 and January 2017 using an optical-based compact scanning mobility particle sizer (SMPS). Diurnal and correlation analysis showed that traffic emissions and meteorological confounding factors were potential driving factors for changes in the PNCs (D(p) 100/cm(3) was influenced by air masses originating from the Indian Ocean and Indochina regions. Receptor models extracted five potential sources of PNCs: industrial emissions, transportation, aged traffic emissions, miscellaneous sources, and a source of secondary origin coupled with meteorological factors. A respiratory deposition model for male and female receptors predicted that the deposition flux of PM(1) (particle mass