Characteristics, sources, toxicity and health risk assessment of ambient size-fractioned urban particulate in Kuala Lumpur

Abstract

Particulate matter (PM) in an urban environment, including nanoparticles, has been shown in previous studies to have detrimental impacts on human health and ecosystems. This study is designed to identify the physico-chemical and toxicity characterization of size-fractioned urban PM in Kuala Lumpur and its temporal variations, including source apportionment, PM deposition and health risk assessment. The samples were collected on quartz and inertial filter using a nanosampler at 40 L min-1 from 17 February until 3 December 2017. The composition of size-fractioned PM was determined for watersoluble ionic ions (WSII), trace elements, polycyclic aromatic hydrocarbons (PAHs) and carbonaceous. Surface morphological and single particle elemental analyses were characterised using Field Emission Scanning Electron Microscope coupled with Energy-Dispersive X-Ray (FESEM-EDX). The toxicity of organic and aqueous PM extract was assessed using microculture tetrazolium, comet and micronucleus assay. The possible sources were apportioned through diagnostic ratio, enrichment factors, principal component analysis (PCA) and positive matrix factorization (PMF). The PM deposition in the respiratory tract was determined, and the health risk assessments were calculated using the US EPA risk calculation. The results showed that the total PM concentration reached the peak during the southwest (SW) season (70.9 ± 6.04 μg m-3), and the PMs with the most significant accumulation were PM0.5–1.0 (22%–30%) and PM2.5–10 (22%–25%). FESEM-EDX analysis found the samples composed of soot aggregates, fly ash, mineral and metallic-rich particles. The SO4 2-, NO3 - and NH4 + significantly contributed to WSII with 76.8±4.1% of the total ions. Trace elements in PM dominated by Mg, Al and Fe represented 35.7±2.1%, 34.4±7.9% and 23.6±6.4%, followed by Zn and Cr with 1.8±0.9% and 1.7±1.04% of the total trace elements concentration, respectively. High molecular weights of PAHs dominated 65% to 85% of the total PAHs concentration. WSII recorded the highest percentage of the total mass in PM0.5–1.0 and PM2.5–10 accounted for 28.4% and 13.5%, respectively. Trace elements, PAHs and carbonaceous most accumulated in PM<0.1 with 37.2%, 0.05% and 23.4%, respectively. During SW, high concentrations were measured including WSII (6.3 μg m-3) and total PAHs (15.8 ng m-3). Based on PCA and PMF inorganic analysis, 21.4% originated from a mixture of crustal, industrial and brake lining, and 28.4% from secondary inorganic aerosol (SIA) + biomass burning, respectively. While PCA and PMF organic analysis showed, biomass and vehicle emission contributed 19.3% and 53.5%, respectively. Toxicity testing revealed that neither cytotoxic, genotoxic, nor clastogenic effects were observed for an organic and aqueous extract for each PM size and season at the highest concentration (100 μg mL-1). Yet, there are significant differences in % DNA in the tail, meaning SW season had stronger effects on potential DNA damages. The largest deposition variability (78.9%) was observed in the upper airways of the respiratory system, with the biggest contributions (38.9%) accumulated as PM2.5-10. In contrast, fine or ultrafine particles (22.1%-28.8%) accumulated mainly in the deepest respiratory tract (alveolar). Non-carcinogenic and carcinogenic health risks showed that the adults and children are below acceptable limits and thus can be negligible. Overall, this study reveals that finer particles dominated total aerosol particle concentration, which comes from anthropogenic activities. High concentrations of pollutants in finer particles and high deposition in the alveolar may have potential adverse effects to population. Moreover, high organic pollutants during the SW season can induce DNA damage in V79 cells