A preliminary investigation of 942 organic micro-pollutants in the atmosphere in waste processing and urban areas, northern Vietnam: Levels, potential sources, and risk assessment

A preliminary investigation of 942 organic micro-pollutants in the atmosphere in waste processing and urban areas, northern Vietnam: Levels, potential sources, and risk assessment

Ecotoxicology and Environmental Safety 167 (2019) 354–364 Contents lists available at ScienceDirect Ecotoxicology and Environmental Safety journal homepage: www.elsevier.com/locate/ecoenv A preliminary investigation of 942 organic micro-pollutants in the atmosphere in waste processing and urban areas, northern Vietnam: Levels, potential sources, and risk assessment T Hoang Quoc Anha,b,c, Keidai Tomiokaa, Nguyen Minh Tued,e, Le Huu Tuyene, Ngo Kim Chif, ⁎ Tu Binh Minhc, Pham Hung Viete, Shin Takahashia, a Center of Advanced Technology for the Environment (CATE), Graduate School of Agriculture, Ehime University, 3-5-7 Tarumi, Matsuyama 790-8566, Japan The United Graduate School of Agricultural Sciences (UGAS-EU), Ehime University, 3-5-7 Tarumi, Matsuyama 790-8566, Japan Faculty of Chemistry, VNU University of Science, Vietnam National University, 19 Le Thanh Tong, Hanoi, Vietnam d Center for Marine Environmental Studies (CMES), Ehime University, 2-5 Bunkyo-cho, Matsuyama 790-8577, Japan e Center for Environmental Technology and Sustainable Development (CETASD), VNU University of Science, Vietnam National University, 334 Nguyen Trai, Hanoi, Vietnam f Institute of Natural Products Chemistry, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet, Hanoi, Vietnam b c A R T I C LE I N FO A B S T R A C T Keywords: Organic micro-pollutants PUF–PAS AIQS–DB Waste processing area Urban area Northern Vietnam Of 942 organic micro-pollutants screened, 167 compounds were detected at least once in the atmosphere in some primitive waste processing sites and an urban area in northern Vietnam by using a polyurethane foam-based passive air sampling (PUF–PAS) method and an Automated Identification and Quantification System with a Database (AIQS–DB) for GC–MS Total concentrations of organic pollutants were higher in samples collected from an urban area of Hanoi city (2300–2600 ng m–3) as compared with those from an end-of-life vehicle (ELV) dismantling area in Bac Giang (900–1700 ng m–3) and a waste recycling cooperative in Thai Nguyen (870–1300 ng m–3) Domestic chemicals (e.g., n-alkanes, phthalate ester plasticizers, and synthetic phenolic antioxidants) dominated the organic pollutant patterns in all the samples, especially in the urban area Pesticides (e.g., permethrins, chlorpyrifos, and propiconazole) were found in the atmosphere around the ELV sites at more elevated concentrations than the other areas Levels of polycyclic aromatic hydrocarbons and their derivatives in the Bac Giang and Thai Nguyen facilities were significantly higher than those measured in Hanoi urban houses, probably due to the waste processing activities Daily intake doses of organic pollutants via inhalation were estimated for waste processing workers and urban residents This study shall provide preliminary data on the environmental occurrence, potential emission sources, and effects of multiple classes of organic pollutants in urban and waste processing areas in northern Vietnam Introduction Air pollution and its potential adverse effects on humans have become an issue of great concern in Vietnam The major sources of air pollutants, e.g., particulate matter (PM), inorganic gases, and organic contaminants, in this developing country have been identified as traffic and construction emissions, inappropriate waste disposal and recycling, and other industrial and agricultural production activities (Huy et al., 2017; Le et al., 2014; Luong et al., 2017; Phung et al., 2016; Tue et al., 2013; Wang et al., 2016a) The strong associations between the daily hospital admissions for acute respiratory diseases and the levels of common air pollutants (e.g., PM10, NO2, SO2) have been observed in the ⁎ metropolitan areas of Hanoi and Ho Chi Minh city (Luong et al., 2017; Nhung et al., 2018; Phung et al., 2016) However, studies on the occurrence and risk assessment of organic micro-pollutants, including highly toxic persistent organic pollutants (POPs), in Vietnam's atmosphere are relatively limited, mainly due to the lack of suitable sampling methods and cost-effective quantification tools Some legacy POPs such as dichlorodiphenyltrichloroethans (DDTs) and polychlorinated biphenyls (PCBs) were found at relatively high concentrations in the ambient air in Vietnam, as compared with some other Asian countries (Wang et al., 2016a) Elevated levels of PCBs and polybrominated diphenyl ethers (PBDEs) were recorded in the atmosphere around some ewaste recycling households in northern Vietnam (Tue et al., 2013) Corresponding author E-mail address: takahashi.shin.mu@ehime-u.ac.jp (S Takahashi) https://doi.org/10.1016/j.ecoenv.2018.10.026 Received 28 August 2018; Received in revised form October 2018; Accepted October 2018 0147-6513/ © 2018 Elsevier Inc All rights reserved Ecotoxicology and Environmental Safety 167 (2019) 354–364 H.Q Anh et al Material and methods Concentrations of phthalate esters, an emerging group of air pollutants, in Vietnamese indoor air were comparable to those detected in some developed countries such as US and Japan (Tri et al., 2017a) Actually, the Vietnamese ambient air is estimated to be polluted by a great number of organic pollutants originating from complex anthropogenic sources (Tri et al., 2017a,b; Tue et al., 2013; Wang et al., 2016a) This finding suggests an urgent need to conduct a comprehensive investigation into the presence and exposure risk of organic air pollutants in Vietnam, especially for urban areas of big cities and primitive waste processing areas The passive air sampling method using polyurethane foam discs (PUF–PAS) was introduced by Shoeib and Harner (2002) for monitoring of POPs such as PCBs and polychlorinated naphthalenes (PCNs) The PUF–PAS method has been widely applied as an alternative to conventional active air sampling (AAS) for organic pollutants because of its advantages of low cost, simple handling, no power supply required, and deployable at many sites at the same time for large scale monitoring (Bogdal et al., 2013; Harner et al., 2006) As reviewed by EsteveTurrillas and Pastor (2016), several semivolatile organic compounds (SVOCs) have been monitored in the atmosphere by using the PUF–PAS method, for example, PCBs, PCNs, brominated flame retardants (BFRs, e.g., PBDEs), polycyclic aromatic hydrocarbons (PAHs), polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs), organochlorine pesticides, current-use pesticides, and other emerging pollutants We have found that PUF–PAS is an appropriate sampling method for organic pollutants, especially for developing countries with limited financial resources (Bogdal et al., 2013; Tue et al., 2013; Wang et al., 2016a) The gas chromatography–mass spectrometry (GC–MS) method operated in selective ion monitoring (SIM) modes exhibits outstanding separation efficiency, high selectivity, and low detection limits However, a conventional GC–MS method usually focuses on one or a few groups of chemicals with similar physicochemical properties and requires much efforts to prepare and operate analytical standards, especially for multi-residue analysis of several hundred analytes To simultaneously determine nearly 1000 SVOCs with different physicochemical properties using GC–MS without using authentic chemical standards, Kadokami et al (2005) introduced a novel screening tool, an Automated Identification and Quantification System with a Database for GC–MS (AIQS–DB/GC–MS) The database consists of three components including mass spectra, retention times, and calibration curves, which are essential for both identifying and quantifying target substances, overcoming some of the limitations of traditional GC–MS analysis (Kadokami et al., 2005) The AIQS–DB/GC–MS method has been efficiently and inexpensively used to quantify hundreds of organic contaminants in aquatic environments such as surface water (Kong et al., 2015), groundwater (Kong et al., 2016), and sediments (Kadokami et al., 2013; Pan et al., 2014) This tool has also been applied to monitor hundred organic micro-pollutants in Vietnamese sewer systems (Ha et al., 2017; Hanh et al., 2014, 2015), and settled dusts collected from end-of-life (ELV) vehicle processing and urban areas in northern Vietnam (Anh et al., 2018) To our knowledge, there have been no studies on the screening analysis of organic pollutants in northern Vietnam In the present study, 942 organic compounds were comprehensively monitored in the air samples collected from an informal ELV dismantling area in Bac Giang province, a waste recycling cooperative in Thai Nguyen province, and an urban area of Hanoi city by using the PUF–PAS coupled with AIQS–DB/GC–MS quantification Concentrations and patterns of multiple organic air pollutants were investigated to provide an overall view of the pollution status and their potential emission sources in some primitive waste processing and urban areas in northern Vietnam Human health risks associated with inhaling organic pollutants were also estimated for waste processing workers and residents in the study areas 2.1 Study areas The ELV dismantling workshops were located in Thuyen village, Bac Giang province, about 60 km northeast of the capital city Hanoi ELVs and other machinery engines from all around the country are collected and then manually dismantled using rudimentary tools such as drop hammers and oxygen-fuel cutting torches The dismantled components are categorized into reusable parts for resale, recyclable materials for recycling, and low value materials for disposal (including open burning) In the survey year 2015, there were about 90 out of a total of 300 households with 200 local workers that were involved in ELV-related activities in Thuyen village, while the rest of population was engaged in agricultural production A waste recycling cooperative located in Tan Cuong commune, Thai Nguyen province, was also investigated in this study Tan Cuong commune, situated 70 km north of Hanoi, is a mountainous area and well known for tea growing, without extensive industrial activities The cooperative under investigation comprised several facilities with different activities such as plastic recycling, rubber tire melting, waste oil refining, and hazardous waste combusting For comparison, Hanoi was chosen as an urban reference site, characterized by a high degree of urbanization and high population density 2.2 Passive air sampling The air samples were collected using the PUF–PAS method with foam discs (136 mm diameter, 13 mm thick, and 0.0140 g cm–3 density; INOAC Corporation) The PUF discs were washed by acetone in Soxhlet extractors for 24 h, dried in a vacuum desiccator, covered in aluminum foil, and sealed in polyethylene bags until deployment Each sampler consisted of two stainless steel bowls (26 and 20 cm diameter for upper and lower bowls, respectively) with a 2-cm gap between the two bowls for air circulation Samplers were deployed at 2–3.5 m above the ground over a sampling period of approximately six weeks At the end of the sampling period, the samplers were disassembled, and the PUF discs were retrieved, resealed, transported to a laboratory, and stored at −20 °C until analysis In the ELV area, a total of ten samples were collected during September–October 2015 from nine ELV workshops (ELV-1 to ELV-9) and one control rural house (RH-1) Three samples were obtained from the waste recycling cooperative in Thai Nguyen: a plastic recycling facility (WR-1), a waste oil refining facility (WR-2), and a rubber melting kiln (WR-3) Samples from three urban houses in Hanoi were also collected (UH-1 to UH-3) Additional information on the sampling sites and deployment position of samplers are provided in Table S1 Air concentrations of pollutants were derived by the amounts accumulated in the PUF discs and the volume of circulated air The sampled air volume is estimated by a sampling duration in days and a sampling rate (m3 d–1) The sampling rates of SVOCs by the PUF–PAS method could be estimated based on calibration studies with AAS references (Bohlin et al., 2014; Shoeib and Harner, 2002), or by using depuration compounds spiked into the collecting medium before deployment (Birgül et al., 2017; Gouin et al., 2005; Pozo et al., 2004) According to the literature, a PUF–PAS outdoor sampler has a linear uptake duration over the first 100 days and sampling rates of 3–5 m3 d–1 for chemicals with n-octanol/air partition coefficients higher than 108.5 (Harner et al., 2004; Jaward et al., 2004; Wilford et al., 2004) The sampling rates of 3.5–4 m3 d–1 have been widely used to derive outdoor air concentrations of typical classes of organic pollutants such as PAHs, organochlorine pesticides (OCPs), PCBs, and PBDEs (Bohlin et al., 2008; Cheng et al., 2013; Choi et al., 2012; Gevao et al., 2006; Jaward et al., 2005; Muenhor et al., 2010; Pozo et al., 2015; Tue et al., 2013; Wang et al., 2010; Zhang et al., 2008) For indoor air, lower sampling rates of 1.66–2.5 m3 d–1 have been also used (Bohlin et al., 2008; Muenhor 355 Ecotoxicology and Environmental Safety 167 (2019) 354–364 H.Q Anh et al et al., 2010) Unfortunately, sampling rate of PUF–PAS method for other classes of organic pollutants, including several groups of emerging contaminants, has not been fully characterized We collected air samples mainly from primitive waste processing facilities with semiopen workplaces reinforced by steel frames and corrugated sheets (see illustration in Table S1), and therefore, we applied generic sampling rates of 3.5 and 2.5 m3 d–1 for samplers deployed at the waste processing workshops and urban houses, respectively Further studies on the calibration and evaluation of PUF–PAS sampling rates for organic pollutants other than POPs are needed sample treatment protocol and quantified them using a conventional GC–MS method operated in SIM mode (GC–MS/SIM) The instrumental conditions for the target analysis of PAHs are summarized in Table S3 Instrument detection limits (IDLs) of most compounds ranged from to 50 ng mL–1 (Kadokami et al., 2012) Method detection limits (MDLs) were derived from the IDLs with an air sample volume of 30 m3 and a final extract volume of 500 μL The MDLs ranged from 0.10 to 1.0 ng m–3 for almost the target compounds, except for few omnipresent compounds such as bis(2-ethylhexyl) phthalate (DEHP) with a MDL value of 10 ng m–3 (see details in Table S5) 2.3 Chemical analysis 2.5 Risk assessment Extraction was carried out according to the method previously described by Tue et al (2013) The PUF discs were Soxhlet extracted with acetone for 16 h A portion of crude extract corresponding to about 30 m3 of air volume was used for AIQS–DB/GC–MS analysis The remaining portion of extract will be used for future studies on other target analysis and bioassays Clean-up procedure was conducted according to Kadokami et al (2012) In brief, crude extract was solvent-exchanged into hexane and purified using an activated silica gel column (Wakogel® S-1, activated at 130 °C for h) The eluate fractions from the silica gel column were concentrated to 500 μL and spiked with 500 ng of each internal standards (1,4-dichlorobenzene-d4, 4-chlorotoluene-d4, acenaphthene-d10, chrysene-d12, fluoranthene-d10, naphthalene-d8, perylene-d12, and phenanthrene-d10; Custom Internal Standard, Restek) before quantification All chemicals used in this study were reagent grade for PCB analysis and obtained from Wako Pure Chemical Industries, Ltd Solvents were re-distilled before use A total of 942 semivolatile organic pollutants were quantified using a gas chromatograph connected to a quadrupole mass spectrometer (GCMS-QP2010 Ultra; Shimadzu) and equipped with AIQS-DB system Target compounds were separated on a fused-silica capillary column (J &W DB-5ms Ultra Inert, 30 m length × 0.25 mm internal diameter ì 0.25 àm lm thickness; Agilent Technologies) Helium was used as carrier gas at a linear velocity of 40 cm s–1 The temperature of the injection port, interface, and ion source was 250, 300, and 200 °C, respectively Initial column oven temperature was set at 40 °C (held for min) and then increased to 310 °C (8 °C min–1, held for min) Analytes were identified and quantified based on predicted retention times, mass spectra, and calibration curves registered in the database Criteria for a detected compound included retention time variation ( ± 0.5 min), mass spectra similarity (> 80%), signal to noise ratio (S/ N > 3), and signal ratio of sample and blank (S/B > 3) Inhalation daily intake doses (DIair – ng kg–1 d–1) of total organic pollutants and some representative contaminants were estimated using the following equation, assuming a 100% absorption rate: DIair = Cair × F × IR/BW Where Cair is concentration of target contaminant (ng m–3), F is fraction of time spent in the respective micro-environment, IR is respiratory rate (m3 d–1), and BW is body weight (kg) F values of 8/24 and 14/24 were assigned for adults at workplaces and dwellings in the waste processing areas, respectively Children under school age are estimated to be taken care of at home with a fraction time of 24/24 The respiratory rates were estimated as 16.0 m3 d–1 for adults and 10.1 m3 d–1 for children (US EPA, 2011) Average body weights of 60 kg and 15 kg were assigned for Vietnamese adults and children, respectively 2.6 Statistical analysis Concentrations below MDLs were treated as zero Statistical analysis was performed using Microsoft Excel (Microsoft Office 2010) and Minitab 16® Statistical Software (Minitab Inc.) Mann-Whitney U-test at a confidence level of 95% was used to assess the differences in contamination levels between study locations Paired t-test at a confidence level of 95% was applied to check the difference between the analytical results of PAHs obtained by the AIQS–DB and conventional methods Log-transformed concentrations of selected pollutants were subjected to Pearson's correlation analysis and principal component analysis (PCA) to evaluate possible relationships Results and discussion 3.1 Comparison of PAH concentrations obtained using the AIQS–DB/ GC–MS method and the conventional GC–MS/SIM method 2.4 Quality assurance and quality control (QA/QC) To validate the accuracy of this screening method, we analyzed some PAHs in the same air samples using the GC–MS/SIM method with isotope dilution quantification The comparison of analytical results of PAHs in the air samples obtained by the two methods is presented in Table S4 Concentrations of the predominant PAH congeners such as fluorene, phenanthrene, fluoranthene, pyrene, and benzo[c]phenanthrene derived by using the screening method were in good agreement with those found by the conventional method The p values from paired t-test obtained for these compounds were greater than 0.05, indicating that the two methods not differ significantly at a confidence level of 95%, particularly for PAH analysis In addition, ratios of the PAH concentrations generated by AIQS–DB method and SIM method ranged from 0.95 ± 0.10 (for fluoranthene) to 1.07 ± 0.13 (for fluorene), partially confirming the accuracy of this novel screening tool as compared with the conventional method Although confirmation using internal standard method showed the negatively systematic errors for few pesticides, Kadokami et al (2009) documented that almost common semivolatile chemicals, excluding highly polar (e.g., pentachlorophenol) and less stable compounds (e.g., benzidine), can be quantified accurately by the AIQS–DB method A procedural blank sample was analyzed simultaneously with each batch of four real samples to check for interference and contamination during chemical analysis Concentrations of target compounds were corrected by subtracting the average blank level To reduce the blank level, glassware was washed with detergent and tap water, dried, baked for h at 450 °C, and rinsed with solvents (i.e., acetone, toluene, and hexane) before use Before analyzing real samples, the recovery test was conducted using procedural blanks (n = 3) spiked with some representative groups of organic pollutants, including 10 OCPs, 62 PCBs, and 19 PAHs and methylated PAHs Recoveries of most compounds ranged from 60% to 120%, except for some PCB congeners (e.g., PCB171, PCB-201, and PCB-202) and two pesticides (e.g., dieldrine and methoxychlor) (Table S2) The relatively high recoveries (over 140%) of some compounds were largely due to the co-elution peaks However, this study focused on comprehensive analysis and semiquantitation of multiple organic pollutants, and therefore, the relatively high recoveries of few individual compounds should not significantly affect overall results For comparison, we selected some PAH congeners and measured their concentrations in the same air samples using a similar 356 Ecotoxicology and Environmental Safety 167 (2019) 354–364 H.Q Anh et al remaining areas of this study Concentrations of some domestic chemicals, typically phthalate ester plasticizers and pharmaceutical and personal care products (PPCPs), showed an opposite trend with a clear urban-rural gradient Results obtained from PCA analysis suggest that the contamination of the urban air was significantly related to domestic chemicals and dyed products, whereas the air in the waste recycling areas was affected more strongly by industrial chemicals and pesticides (Fig S1) A more detailed evaluation of the contamination degree, distribution pattern, and potential sources of organic pollutants in the investigated areas will be described in the next sections In terms of detection limits, the MDLs obtained by screening method (scan mode) were usually higher than those of the conventional method (SIM mode) In this study, the MDLs of PAHs from scan mode were about 0.10 ng m–3, which were one to two orders of magnitude higher than the values derived by SIM mode (from 0.0010 to 0.010 ng m–3) Therefore, some PAHs at trace levels were not detected in most samples in this study by using the AIQS–DB method, including compounds with high mutagenic and carcinogenic potency such as benzo[a]-, dibenzo [a,h]-, dibenzo[a,i]-, and dibenzo[a,l]pyrene A similar situation was expected for other pollutants such as PCBs and PBDEs, which were previously found in Vietnamese ambient air in minor concentrations at pg m–3 levels (Tue et al., 2013; Wang et al., 2016a) This finding suggests the need for further target analysis to determine highly toxic and trace-level contaminants, such as dioxins and related compounds However, it should be re-emphasized that this screening method can provide a comprehensive insight into the total concentrations of major organic pollutants from different emission sources 3.3 Levels and profiles of domestic chemicals A total of 73 domestic chemicals, including 20 n-alkanes, 11 plasticizers (i.e., phthalate and adipate esters), 10 fatty acid methyl esters (FAMEs), 12 PPCPs, synthetic antioxidants, and 14 miscellaneous compounds (e.g., disinfectants, fragrances, detergent metabolites), were detected in the air samples of this study (Table and S5) Concentrations of domestic chemicals ranged from 560 to 2300 ng m–3 (median 920 ng m–3) This chemical group was the most dominant category, accounting for 62–91% (average 75%) of total organic pollutants The highest domestic chemical concentration was measured in an urban house in Hanoi (UH-2), whereas the lowest level was found in the rural house in Bac Giang (RH-1) A significant difference was observed in concentrations of domestic chemicals between the Hanoi urban area and the ELV dismantling area (p < 0.05) The most dominant contributors to total levels of domestic groups were plasticizers, n-alkanes, and SPAs The abundance of domestic chemicals in the air samples of this study suggests that household and business activities with increased use of new consumer products have been important sources of organic pollutants, especially in metropolitan areas 3.2 Overview of contamination status A total of 167 organic pollutants, comprising 73 domestic chemicals, 68 industrial chemicals and 26 pesticides, were detected at least once in the air samples of this study Air concentrations of total organic pollutants classified by their origins and uses, and the number of detected compounds in each sampling site are presented in Table and Fig Air concentrations of individual pollutants are tabulated in Table S5 As the sampling rates of PUF–PAS method have not been characterized for all the detected compounds in this study, absolute mass concentrations of organic pollutants (μg per sampler) are provided in Table S6 However, in the main text, we use derived air concentrations (ng m–3) to facilitate comparison with other studies The overall concentrations of organic pollutants ranged from 870 to 2600 ng m–3 (median 1300 ng m–3) The highest contamination level was detected in the indoor air of an urban house in Hanoi (UH-2), and the urban indoor air samples showed a higher abundance of organic pollutants than those collected from the waste processing sites (p < 0.05) Domestic chemicals such as n-alkanes, phthalate ester plasticizers, and synthetic phenolic antioxidants (SPAs) dominated the organic pollutant patterns in all the samples, especially in the urban indoor air (about 90%) Significant proportions of domestic chemicals were also recorded in sediments from the sewer systems of Hanoi and Ho Chi Minh City (Hanh et al., 2014), implying the negative environmental impacts of household and business activities, especially in the metropolitan areas Total pesticide concentrations were the highest in samples from Bac Giang, while there was no significant difference in the concentration of industrial pollutants between study locations A comparison between concentrations of selected classes of organic pollutants, including PAHs and substituted PAHs, pyrethroid insecticides, pharmaceutical and personal care products (PPCPs), and phthalate and adipate ester plasticizers, in the air of our sampling sites is presented in Fig PAHs and their derivatives were observed at higher levels at the waste processing sites than in the urban area Although the contamination status of PAHs has been investigated in the environment such as in outdoor air and road dust from some Vietnamese urban areas (Hien et al., 2007a,b,c; Tuyen et al., 2014a,b; Kishida et al., 2008, 2009), information about the occurrence of these carcinogenic pollutants in Vietnamese working environments is limited These preliminary data on the concentrations of PAHs and related compounds in the air of the ELV workshops in northern Vietnam partially confirmed the role of inappropriate waste processing activities as a potential source of PAHs Concentrations of some pesticides such as permethrins, chlorpyrifos, and propiconazole were more elevated in samples collected from the Bac Giang ELV sites than the remaining sites It should be noted that Thuyen village is a rural area with intensive agricultural activities such as rice and crop cultivation, resulting in widespread use of agrochemicals in this area as compared to the 3.3.1 n-Alkanes A total of 20 n-alkanes (C10 to C32, excluding C11, C12, and C13) were detected in the air samples at a range of 17–410 ng m–3 (median 150 ng m–3) (Table and Fig S2) The highest n-alkane concentrations were found in the sample collected from an ELV workshop (ELV-2; 410 ng m–3) with relatively large amounts of waste engine oil released (about 50–60 L per month), followed by the sample taken near a waste rubber melting furnace (WR-3, 280 ng m–3) Levels of n-alkanes in urban indoor air (130–250 ng m–3) were comparable to those measured in the waste processing areas Our results were in line with levels detected in ambient air from urban areas of Beijing (163.0 ± 193.5 ng m–3 in PM2.5; Huang et al., 2006) and Guangzhou (141–392 ng m–3 in PM10; Bi et al., 2002), China; and Delhi, India (187.4 ± 4.3 ng m–3 in PM10; Gupta et al., 2017) Levels of n-alkanes in this study were much higher than those observed in Hong Kong, China (average 23.5 ng m–3 in PM2.5; Zheng et al., 2000); an urban site of Venice, Italy (15.12–38.88 ng m–3 in PM1; Valotto et al., 2017); and some remote areas such as Lulang, Tibetan Plateau (0.10–21.83 ng m–3 in total suspended particulates; Chen et al., 2014) and a forest in Finland (7–95 ng m–3 in aerosol particles; Rissanen et al., 2006) The emission sources of n-alkanes can be estimated by their congener profiles and several diagnostic parameters, for instance, carbon number of the most abundant alkanes (Cmax), carbon preference index (CPI), ratio of low-molecular-weight to high-molecular-weight alkanes (LHR), and contribution of plant wax n-alkanes (WNA%) (see details in Fig S2 and Table S7) Samples from the ELV workshops showed the major petrogenic sources of n-alkanes with low Cmax values (C17–20), most CPI and LHR values close to unity, and low WNA% (7–17%) (Guo and Fang, 2012; Gupta et al., 2017; Ladji et al., 2014; Xu et al., 2013) In contrast, samples from the rural house in Bac Giang (RH-1), two urban houses in Hanoi (UH-1 and UH-2), and a plastic recycling facility in Thai Nguyen (WR-1) presented higher values of WNA% (25–70%), suggesting the possible emissions of n-alkanes from biogenic sources (Chen et al., 2014; Yuan et al., 2016) and/or human activities such as biomass 357 H.Q Anh et al Table Concentrations of organic micro-pollutants (ng m–3) in the atmosphere in waste processing and urban areas, northern Vietnam Numbers in parentheses indicate numbers of detected compounds ELV dismantling area (Bac Giang) Waste recycling facilities (Thai Nguyen) Urban area (Hanoi) 358 ELV-1 ELV-2 ELV-3 ELV-4 ELV-5 ELV-6 ELV-7 ELV-8 ELV-9 RH-1 WR-1 WR-2 WR-3 UH-1 UH-2 UH-3 Domestic chemicals (73) n-Alkanes (20) Plasticizers (11) Antioxidants (6) Fatty acid methyl esters (10) PPCPs and related compounds (12) Other domestic chemicals (14) Industrial chemicals (68) PAHs (13) Substituted PAHs (12) Intermediates for dyes (10) Intermediates for organic synthesis (21) Other industrial chemicals (12) Pesticides (26) Insecticides (13) Fungicides (7) Herbicides (6) Total concentration (167) 680 (46) 110 (18) 48 (5) 420 (6) 37 (6) 13 (3) 1100 (46) 410 (19) 96 (6) 410 (6) 59 (7) 29 (3) 700 (43) 110 (16) 90 (6) 390 (6) 37 (6) 15 (3) 960 (40) 67 (15) 260 (6) 540 (6) 36 (4) 13 (3) 740 (48) 210 (19) 330 (8) 91 (5) 20 (3) 30 (4) 930 (43) 170 (16) 120 (6) 530 (6) 40 (4) 19 (4) 980 (47) 160 (17) 86 (6) 610 (6) 49 (7) 22 (4) 900 (43) 190 (16) 110 (6) 500 (6) 20 (4) 18 (4) 680 (46) 110 (17) 80 (6) 390 (6) 33 (5) 17 (4) 560 (46) 58 (16) 51 (6) 340 (6) 54 (7) 10 (3) 780 (39) 17 (7) 460 (9) 210 (6) 14 (3) 22 (4) 670 (43) 130 (17) 350 (8) 120 (6) 1.3 (1) 23 (4) 960 (51) 280 (15) 140 (8) 360 (6) 37 (5) 89 (6) 2100 (46) 250 (15) 1000 (8) 490 (4) 29 (3) 190 (8) 2300 (51) 130 (15) 1200 (9) 510 (4) 48 (4) 250 (7) 2100 (53) 220 (18) 870 (9) 410 (4) 70 (3) 340 (8) 47 (8) 110 (41) 43 (13) 17 (7) 6.3 (1) 20 (10) 53 (5) 190 (40) 50 (9) 72 (10) 12 (1) 28 (10) 53 (6) 120 (38) 43 (9) 17 (6) 7.6 (3) 30 (11) 48 (6) 130 (35) 43 (7) 20 (8) 6.9 (2) 29 (8) 59 (9) 170 (45) 61 (12) 45 (11) 11 (3) 31 (10) 49 (7) 130 (41) 43 (11) 30 (9) 8.4 (1) 29 (11) 56 (7) 100 (36) 32 (8) 20 (8) 6.8 (1) 24 (9) 57 (8) 150 (38) 52 (11) 32 (9) 10 (1) 34 (10) 52 (8) 110 (38) 35 (10) 13 (4) 8.5 (3) 38 (12) 49 (8) 93 (34) 35 (8) 10 (4) 2.7 (2) 28 (11) 57 (10) 62 (32) 7.3 (6) 11 (7) 21 (7) 8.9 (7) 44 (7) 160 (48) 57 (11) 38 (11) 16 (5) 35 (13) 56 (11) 150 (44) 69 (8) 23 (9) 14 (5) 26 (13) 110 (8) 90 (28) 16 (5) 17 (8) 16 (2) 23 (8) 130 (12) 150 (29) 17 (5) 7.0 (6) 38 (5) 61 (7) 150 (11) 88 (28) 22 (5) 12 (8) 14 (3) 18 (6) 21 (10) 240 (10) 190 (6) 40 (2) 14 (2) 1000 (97) 23 (10) 370 (10) 290 (5) 78 (3) 1.5 (2) 1700 (96) 24 (9) 230 (11) 180 (5) 35 (3) 15 (3) 1100 (92) 26 (10) 130 (10) 110 (6) 8.8 (1) 12 (3) 1200 (85) 26 (9) 56 (8) 36 (2) 17 (4) 2.6 (2) 1000 (101) 22 (9) 250 (13) 180 (6) 58 (5) 12 (2) 1300 (97) 20 (10) 330 (13) 250 (6) 65 (3) 16 (4) 1400 (96) 18 (7) 250 (12) 180 (5) 61 (4) 13 (3) 1300 (93) 17 (9) 260 (12) 200 (6) 52 (3) 3.5 (3) 1100 (96) 18 (9) 250 (12) 210 (6) 23 (2) 16 (4) 900 (92) 14 (5) 52 (7) 31 (4) 2.5 (1) 18 (2) 900 (78) 14 (8) 43 (5) 7.0 (3) 1.9 (1) 34 (1) 870 (96) 14 (9) 150 (11) 120 (6) 13 (3) 17 (2) 1300 (106) 18 (5) 77 (6) 65 (2) 10 (2) 1.6 (2) 2300 (80) 26 (6) 110 (9) 88 (4) 6.0 (2) 11 (3) 2600 (89) 22 (6) 60 (3) 57 (2) 3.1 (1) n.d (0) 2300 (84) n.d – not detected Ecotoxicology and Environmental Safety 167 (2019) 354–364 Category (detected number) Ecotoxicology and Environmental Safety 167 (2019) 354–364 H.Q Anh et al Fig Total concentrations (ng m–3) of organic micro-pollutants in the atmosphere in waste processing and urban areas, northern Vietnam (DNBP) and diisobutyl phthalate (DIBP), whereas the remaining sites were mainly polluted by DNBP and DIBP (Fig S3) Results from PCA analysis presented in Fig S4 have revealed the association between phthalate esters and their potential sources The correlation between DEHP and DCHP suggests their sources as articles made of vinyl chloride resins, where they are widely used as plasticizers (Otake et al., 2004) DNBP and DIBP were strongly related, indicating a similar environmental behavior and fate, and the same applications as plasticizers and additives in cosmetics and personal care products (He et al., 2018; Zhang et al., 2018) burning (Chen et al., 2017; Valotto et al., 2017) 3.3.2 Plasticizers Phthalate and adipate esters were detected in a wide concentration range of 51–1200 ng m–3 (median 130 ng m–3) Levels of total phthalate and adipate esters were the highest in Hanoi (median 1000 ng m–3; range 870–1200 ng m–3), followed by the waste recycling facilities in Thai Nguyen (350; 140–460 ng m–3) and the ELV dismantling area (93; 48–330 ng m–3) (Table and Fig S3) The highest concentration of plasticizers in waste processing areas was found in a sample collected from the plastic recycling facility in Thai Nguyen (WR-1; 460 ng m–3) Phthalate ester concentrations in Hanoi indoor air in this study were within the range previously reported by Tri et al (2017a) for urban homes in the same area (low-volume air sampling, 210–2400 ng m–3) Our values were lower than those measured in indoor air from hair salons in Hanoi (mean 3590; range 569–16,000 ng m–3; Tri et al., 2017a), and offices in Hangzhou, China (3070–6700 ng m–3; Song et al., 2015), and hospitals in China (16,300–24,190 ng m–3; Wang et al., 2015) Samples from Hanoi and some waste processing sites (e.g., ELV5, WR-1, and WR-2) were dominated by DEHP and dicyclohexyl phthalate (DCHP) with a significant contribution of di-n-butyl phthalate 3.3.3 Antioxidants SPAs such as 2-tert-butyl-4-hydroxyanisole (BHA) and 2,6-di-tertbutyl-4-hydroxytoluene (BHT) and its metabolites, including 3,5-di-tertbutyl-4-hydroxybenzaldehyde (BHT-CHO) and 2,4-di-tert-butyl-1,4benzoquinone (BHT-Q), were detected in air samples at elevated concentrations (median 410; range 89–610 ng m–3, Fig S5) BHT and BHA are commonly used as antioxidants in petroleum products, polymeric materials, cosmetics and personal care products, and foodstuffs (NievaEchevarría et al., 2015; Liu et al., 2017; Wang and Kannan, 2018) Although several previous studies have indicated the association Fig Concentrations of selected groups of organic micro-pollutants (ng m–3) in the atmosphere in waste processing and urban areas, northern Vietnam 359 Ecotoxicology and Environmental Safety 167 (2019) 354–364 H.Q Anh et al phenanthrene, fluoranthene, fluorene and pyrene (Table S5 and Fig S6) The highest PAH concentration was detected in the air around the rubber melting kiln in Thai Nguyen (WR-3) Levels of atmospheric PAHs at the Bac Giang ELV sites were significantly higher than those measured in the Hanoi urban area (p < 0.05) A worldwide comparison of air concentrations of PAHs generated by using PUF–PAS method, is presented in Table S8 The air concentrations of PAHs found in this study were in good agreement with previous studies conducted in some other locations in China (Wang et al., 2010); Korea (Choi et al., 2012); Chile (Pozo et al., 2012); and Mexico, Sweden, and UK (Bohlin et al., 2008) Higher levels of PAHs were reported in the ambient air from Istanbul, Turkey (mean 85.6; range 11.7–302 ng m–3; Cetin et al., 2017), and a petrochemical industrialized area in Lanzhou, China (mean 302; range 125–680 ng m–3; Wang et al., 2017) Information about the contamination of PAHs in Vietnamese indoor environments is limited Kishida et al (2008) measured PAHs in both particulate matter and gas phase at some outdoor sites in Hanoi and reported relatively high concentrations of PAHs in the bulk air (average 280 ng m–3 for intersection and roadside sites, and 1000 ng m–3 for a site located near a terminal for buses and trucks) This observation suggests traffic emission as an important source of PAHs in big cities The ratios of fluoranthene/(fluoranthene + pyrene) in our samples ranged from 0.46 to 0.60, reflecting PAH emission sources from the combustion processes of petroleum, coal, and biomass (Yunker et al., 2002) Results of PCA analysis tabulated in Fig S7 indicate contributions of coal combustion and industrial/vehicle emission to the releases of PAHs in our study areas (Mao et al., 2016; Wang et al., 2017) between SPAs and their transformation products and adverse effects on animals (Al-Akid et al., 2001; Nagai et al., 1993; Oikawa et al., 1998; Rao et al., 2000), information about the contamination status of these compounds in indoor environment is very scarce (Liu et al., 2017; Wang et al., 2016b) To our knowledge, the data in this study are among the first about SPAs in the air of Vietnam The difference between total SPA concentrations in the atmosphere in urban and waste processing areas was not significant, suggesting their ubiquitous occurrence in Vietnam's environment However, their distribution patterns were quite different between study areas (Fig S5) Most samples from the waste processing areas (except for ELV-5) were dominated by BHT (46–80% of total SPAs), whereas the urban samples showed a prevalence of BHT-CHO and BHT-Q (79–95%) Concentrations of BHT-CHO and BHT-Q were strongly correlated (Pearson's r = 0.925, p < 0.001, for all samples), but a significant association between BHT and BHT-CHO (r = 0.618, p < 0.05) was observed only for samples from the ELV dismantling area The patterns of BHT and its metabolites varied among locations, probably due to the different sources of SPAs and effects of human activities This finding suggests the need for more extensive investigations on these common air pollutants 3.3.4 Other domestic chemicals Thymol, acetophenone, and squalane were among the most frequently detected PPCPs in our air samples, suggesting their popular use in cosmetics and personal care products Concentrations of acetophenone measured in this study (median 3.8; range n.d – 9.9 ng m–3) were significantly lower than those found in indoor air in Leipzig, Germany (190; 6.6–5570 ng m–3, using single charcoal sorbent wafer passive samplers; Rösch et al., 2014) Aspirin and ibuprofen, two common triggers of asthma, were only detected in the urban samples at relatively high abundance as compared with other PPCPs (maximum 240 and 57 ng m–3, respectively) Triclosan, a widely used antibacterial and antifungal agent, was found in all the Hanoi samples at concentrations of 2.3–6.3 ng m–3 Caffeine was detected in some ELV workshops at a maximum concentration of 9.0 ng m–3 FAMEs were observed in all the samples with no clear trend in the contamination degree and profile Concentrations of 2-ethyl-1-hexanol in the Hanoi urban houses (50–71 ng m–3) were higher than those measured in the waste processing sites (11–30 ng m–3), but they were several orders of magnitude lower than levels recorded in German dwellings (0.3055–153.59 μg m–3; Rösch et al., 2014) Recent studies have indicated the abundance of some other emerging organic pollutants in indoor environment from Vietnam, for example, p-hydroxybenzoic acid esters (parabens), bisphenol A diglycidyl ether (BADGE), and cyclic and linear siloxanes (Tri et al., 2015, 2016, 2017a,b) However, these groups have not been registered in the AIQS–DB system According to Kadokami et al (2005), it is possible to add new compounds to the database, suggesting that expanding the database size should be considered in near future 3.4.2 Substituted PAHs There were 12 alkyl and phenyl substituted PAHs found in the air samples with total concentrations from 7.0 to 72 ng m–3 (median 19 ng m–3) (Table S5) Similar to the parent PAHs, concentrations of substituted PAHs were higher in the waste processing areas than urban sites A moderate correlation between total concentrations of parent and substituted PAHs was observed (r = 0.587, p < 0.05), indicating similar emission sources of these two groups (Chen et al., 2017; Tuyen et al., 2014b) The most frequently detected compounds were 1-methylphenanthrene and 2-methyl-, 1-phenyl-, and 2-phenylnaphthalene In almost all the samples, the ratios of total methylated naphthalenes to naphthalene were larger than one, which are commonly observed in other environmental media such as soil (Chen et al., 2017) and sediment (Vondrácek et al., 2007) Ratios of methylated phenanthrenes/ phenanthrene and total methylated PAHs/parent PAHs in most samples were lower than one, confirming the pyrogenic sources of PAHs and their derivatives in these areas (Chen et al., 2017; Tuyen et al., 2014b; Vondrácek et al., 2007) However, atmospheric levels of substituted PAHs exceeded parent PAHs in some waste processing facilities, implying petrogenic sources of PAHs (Saha et al., 2009) Further studies should be performed to get more in-depth insights into the emission behaviors and environmental fate of PAHs and related compounds in other areas in Vietnam, for instance, industrial parks, informal waste recycling areas, and waste dumping and open burning sites 3.4 Levels and profiles of industrial chemicals In the air samples of this study, we detected 68 industrial chemicals, comprising 25 PAHs and their derivatives, 10 intermediates for dyes, 21 intermediates for organic synthesis, and 12 compounds of other applications such as solvents, dielectric fluids, and heat storage and transfer agents Concentrations of total industrial chemicals ranged from 62 to 190 ng m–3 (median 130 ng m–3) and accounted for an average of 10% of total organic pollutants The highest industrial chemical concentration was found in a sample collected from an ELV workshop (ELV-2) There was no significant difference in the air concentrations of industrial chemicals between the study areas 3.4.3 Other industrial chemicals The contribution of intermediates in dyes, intermediates for organic synthesis and other industrial chemicals to total organic air pollutants ranged from 2.3% to 7.5% (average 4.8%) Concentrations of these chemicals did not show a clear trend between study areas Benzothiazole, biphenyl, dibenzofuran, 4-tert-butylphenol, o- and mcresol, carbazole, and　anthraquinone were the most frequently detected compounds Benzothiazole has been used as a vulcanization accelerator in rubber production and as an additive in a variety of consumer products This compound has been widely detected in different environmental and biological matrices, including human bodies, becoming an emerging contaminant of considerable interest (Wan et al., 2016) Benzothiazole was detected in all the samples in this study in a 3.4.1 PAHs Concentrations of total PAHs ranged from 7.3 to 69 ng m–3 (median 43 ng m–3) and dominated by 3- and 4-ring compounds such as 360 Ecotoxicology and Environmental Safety 167 (2019) 354–364 H.Q Anh et al termiticide application (1–350 ng m–3; Dai et al., 2003) This insecticide was found at relatively low concentrations in the indoor air of French dwellings (< 0.6–1.2 ng m–3 and < 0.002–0.007 ng m–3 for gas and particulate phase, respectively; Blanchard et al., 2014) Fenobucarb, a carbamate insecticide, was detected in all the samples from the ELV sites (median 2.2; range 1.4–3.3 ng m–3) Concentrations of chlorpyrifos and fenobucarb in our samples were still lower than guideline values of and 33 μg m–3, respectively, established for indoor air by the Ministry of Health, Labour and Welfare of Japan (MHLW, 2002) Wang et al (2016a) reported the occurrence of several organochlorine pesticides (e.g., DDTs, hexachlorocyclohexanes, hexachlorobenzene, endosulfans, chlordanes, and mirex) in the atmosphere of Vietnam with the maximum concentration for an individual compound of about ng m–3 These legacy POP pesticides were not detected in the samples of our study, probably due to their decreased usage in Vietnam and the high detection limits of these compounds by the screening method narrow range of concentrations (median 9.3; range 3.6–12 ng m–3) The bulk air concentrations (particulate and vapor phases) of benzothiazole in indoor air samples collected from various micro-environments in Albany, New York, US, varied over a wide range (median 20.7; 2.94–1703 ng m–3; Wan et al., 2016) and were much higher than those measured in our samples Some other pollutants such as 1,2,4-trichlorobenzene (used as dielectric fluids), heat transfer agents (e.g., oand p-terphenyl), and industrial sovents (e.g., isophorone and transdecalin) were found only in the air from the waste processing sites Using this screening method, we did not detect some typical industrial contaminants such as PCBs and PBDEs, although they have been observed in the atmosphere from some areas in Vietnam (Tue et al., 2013; Wang et al., 2016a) This finding suggests the need for trace-level target analysis of these highly toxic substances in atmospheric environments in northern Vietnam 3.5 Levels and profiles of pesticides 3.6 Human exposure to organic air pollutants There were 26 pesticides, including 13 insecticides, fungicides, and herbicides, detected in the air samples in this study Concentrations of total pesticides ranged from 43 to 370 ng m–3 (median 190 ng m–3) and decreased in the following order: Bac Giang ELV dismantling area > Hanoi urban area > Thai Nguyen waste recycling facilities (Table and Fig S8) The average contributions of pesticides to total organic pollutants in samples from Bac Giang, Thai Nguyen and Hanoi were 20%, 7.4% and 3.4%, respectively The greater abundance of pesticides in the air around the ELV sites may result from their widespread use for both agricultural and domestic purposes in this rural area Daily intake doses via inhalation (DIair) of total organic air pollutants and selected contaminants estimated for waste processing workers in Bac Giang and Thai Nguyen, and residents in the Hanoi urban area, are summarized in Table S9 Residents in Hanoi were estimated to receive the highest doses of total organic pollutants, mainly contributed by chemicals released from household and business activities Phthalate esters (e.g., DNBP and DEHP) were among the most dominant contributors to the total uptake of organic pollutants by urban inhabitants Our DIair values derived for phthalate esters were consistent with those reported in a survey conducted in four northern cities in Vietnam (Tri et al., 2017a) but were generally higher than the doses estimated for residents in the urban center of Paris, France (8.95 and 3.13 ng kg–1 d–1 for DNBP and DEHP, respectively; Martine et al., 2013) It has been documented that the main routes of exposure to phthalate esters, particularly high-molecular-weight compounds like DEHP, are dust ingestion (Pelletier et al., 2017) and dietary (Martine et al., 2013), suggesting the need for multiple risk assessments The daily intake of PAHs such as fluoranthene and pyrene via inhalation estimated for waste processing workers was higher than those derived for urban residents in Hanoi, as well as residents in the suburbs of Tokyo, Japan (Suzuki and Yoshinaga, 2007) However, the daily intake doses received by Hanoi children were significantly lower than the levels reported for newborns and infants from Karvina city, the most air-polluted part of the Czech Republic affected by black coal mining and coke and steel production activities (Pulkrabova et al., 2016) Residents in Hanoi were exposed to higher inhalation doses of benzothiazole (median 6.1 and 1.4 ng kg–1 d–1 for children and adults, respectively), compared with the doses received by waste processing workers The DIair values of benzothiazole in our study were generally lower than those estimated for inhabitants in Albany, New York, US (median 9.19 and 3.99 ng kg–1 d–1 for children and adults, respectively; Wan et al., 2016) A median DIair of chlorpyrifos of 1.7 ng kg–1 d–1 was derived for the ELV dismantling workers in Bac Giang, which was about two orders of magnitude greater than the value calculated for French population (2.11 × 10–2 ng kg–1 d–1; Pelletier et al., 2017) Almost all the DIair values presented in this study were markedly lower than respective reference doses, indicating insignificant health risk associated with the inhalation of these organic pollutants Nevertheless, the more extensive assessments, considering multiple exposure pathways and trace-level but highly toxic pollutants (e.g., dioxins and related compounds, PCBs, and BFRs), should be conducted in Vietnam, especially in areas under rapid industrialization and urbanization 3.5.1 Pyrethroid insecticides Pyrethroids with the major class of permethrins were found as the most dominant pesticides, accounting for 48–93% of total pesticide concentrations (except for one facility in Thai Nguyen, WR-2) Pyrethroids have been widely applied not only outdoors in agriculture to control insects but also indoors for public health protection Permethrins dominated the total pesticides in river sediments from Hanoi and Ho Chi Minh City (Hanh et al., 2014) Levels of pyrethroids in Vietnamese sediments were generally higher than those from US, UK, Australia and China (Li et al., 2017) Moreover, it has been suggested that pyrethroid residues are higher indoors and their degradation rates are much slower in indoor than outdoor environments (Tang et al., 2018) Concentrations of total pyrethroids in the indoor air in this study (median 120 ng m–3; maximum 230 ng m–3) were significantly higher than levels reported in homes of the Bangkok metropolitan region, Thailand (total pyrethroids 0.01–2.16 ng m–3; Pentamwa et al., 2011) and dwellings in Brittany, western France (permethrin concentrations < 0.6 ng m–3 and < 0.002 ng m–3 for gas phase and airborne particles, respectively; Blanchard et al., 2014) Nevertheless, pyrethroid concentrations in our study were several orders of magnitude lower than those measured in some areas in China (0.01–2.69 mg m–3; as reviewed by Tang et al., 2018) 3.5.2 Other pesticides Propiconazole, chlorpyrifos, thiocyclam, and difenzoquat metilsulfate were the important contributors to total pesticides and found at the ELV sites at high detection frequencies Propiconazole (an azole fungicide) and chlorpyrifos (an organophosphorus insecticide) are registered for agricultural use in Vietnam, and they have been commonly detected in the aquatic environment in agricultural areas in the country (Chau et al., 2015; Hanh et al., 2014; Thuy et al., 2012) However, information about levels of these pesticides in the Vietnamese air is scarce Concentrations of chlorpyrifos in the ambient air from the Bac Giang ELV sites ranged from < 1.0–38 ng m–3 (median 19 ng m–3) and were within the range detected in Korean childcare facilities (median 27; range < 1–58 ng m–3; Kim et al., 2013) and Japanese houses with Conclusions This study is the first to report data on the levels, accumulation profiles, potential emission sources, and exposure risk related to 361 Ecotoxicology and Environmental Safety 167 (2019) 354–364 H.Q Anh et al multiple classes of organic micro-pollutants in the air from waste processing and urban areas in northern Vietnam A large number of 167 organic pollutants belonging to three categories such as domestic chemicals, industrial chemicals, and pesticides, were detected, with their sources revealed to be from business/household, agricultural, and waste processing activities Total concentrations of organic air pollutants were the highest in samples from the Hanoi urban 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