Atmospheric size-resolved trace elements in a city affected by non-ferrous metal smelting: Indications of respiratory deposition and health risk

Effect modification of diet and vitamins on the association between air pollution particles of different diameters and hypertension: A 12-year longitudinal cohort study in densely populated areas of China

INTRODUCTION

Particulate matter (PM) is identified as one of the exacerbating and triggering factors for hypertension. Diet intake and the consumption of vitamins may potentially moderate the impact of PM on hypertension.

METHODS

A 12-year longitudinal cohort study was conducted on a population in densely populated areas of China. Residual balancing with weighted methods was employed to control for time-varying and no time-varying confounding factors. Stratified Cox proportional hazards models were conducted to examine the moderating effects of diet and vitamins on the risk of hypertension with PM.

RESULTS

There was a significant positive association between long-term exposure to different diameter PM and the risk of developing hypertension. The hazard ratios (HRs) for hypertension were 1.0200 (95 % CIs: 1.0147, 1.0253) for PM1, 1.0120 (95 % CIs: 1.0085, 1.0155) for PM2.5, and 1.0074 (95 % CIs, 1.0056, 1.0092) for PM10. The diet and vitamins moderated these associations, the intake of healthy foods and vitamins exhibited a significant positive moderating effect on the relationship between PM exposure and hypertension risk. Among all participants, the high intake of fruit (PM1 (HRs: 1.0102, 95 % CIs: 1.0024, 1.0179), PM2.5 (HRs: 1.0060, 95 % CIs: 1.0011, 1.0109), and PM10 (HRs: 1.0044, 95 % CIs: 1.0018, 1.0070)) and vitamin E (PM1 (HRs: 1.0143, 95 % CIs: 1.0063, 1.0223), PM2.5 (HRs:1.0179, 95 % CIs: 1.0003, 1.0166), and PM10 (HRs: 1.0042, 95 % CIs: 1.0008, 1.0075)) with lower risk of hypertension than the overall level and low intake of related foods and vitamins, exhibited a strong positive moderating effect on the relationship between PM and hypertension. Similar trends were observed for the intake of fish, root food, whole grains, eggs, fungus food, vitamin B2, B3. However, Na, meat, sugary and alcoholic exhibited opposite trends. The moderating effect of vitamin E intake was stronger than vitamin B and C.

CONCLUSIONS

Diet and vitamins intake may moderate the association between PM exposure and the risk of hypertension in adults.

Assessing metal(loid)s-Induced long-term spatiotemporal health risks in Coastal Regions, Bay of Bengal: A chemometric study

Despite sporadic and irregular studies on heavy metal(loid)s health risks in water, fish, and soil in the coastal areas of the Bay of Bengal, no chemometric approaches have been applied to assess the human health risks comprehensively. This review aims to employ chemometric analysis to evaluate the long-term spatiotemporal health risks of metal(loid)s e.g., Fe, Mn, Zn, Cd, As, Cr, Pb, Cu, and Ni in coastal water, fish, and soils from 2003 to 2023. Across coastal parts, studies on metal(loid)s were distributed with 40% in the southeast, 28% in the south-central, and 32% in the southwest regions. The southeastern area exhibited the highest contamination levels, primarily due to elevated Zn content (156.8 to 147.2 mg/L for Mn in water, 15.3 to 13.2 mg/kg for Cu in fish, and 50.6 to 46.4 mg/kg for Ni in soil), except for a few sites in the south-central region. Health risks associated with the ingestion of Fe, As, and Cd (water), Ni, Cr, and Pb (fish), and Cd, Cr, and Pb (soil) were identified, with non-carcinogenic risks existing exclusively through this route. Moreover, As, Cr, and Ni pose cancer risks for adults and children via ingestion in the southeastern region. Overall non-carcinogenic risks emphasized a significantly higher risk for children compared to adults, with six, two-, and six-times higher health risks through ingestion of water, fish, and soils along the southeastern coast. The study offers innovative sustainable management strategies and remediation policies aimed at reducing metal(loid)s contamination in various environmental media along coastal Bangladesh.

Impact of altitude on the dosage of indoor particulates entering an individual's small airways

The complexity of indoor particulate exposure intensifies at higher altitudes owing to the increased lung capacity that residents develop to meet the higher oxygen demands. Altitude variations impact atmospheric pressure and alter particulate dynamics in ambient air and the human respiratory tract, complicating particulate inhalation. This study assessed the fraction of PM2.5 and PM10 entering small airways. This assessment covered an altitude range from 400 m above sea level to 3650 m, and an in vitro respiratory tract model was used. The experimental results confirmed that with increasing altitude, the penetration fractions of PM2.5 and PM10 significantly increased from 0.133 ± 0.031 and 0.141 ± 0.045 to 0.404 ± 0.159 and 0.353 ± 0.132, respectively. Additionally, the computational fluid dynamics simulation results revealed that among particles with sizes of 0.1 to 10 µm, the 7.5-μm particles exhibited the most substantial reduction in deposition in the upper airway, displaying a decrease of 6.27%. Our findings underscore the health risks faced by low-altitude residents during acclimatization to higher altitudes, as they experience heightened exposure to particulate matter sources.

Reconstruction of a century of air pollution history in Nanjing, China, using trace elements in situ leaf specimens of Platanus × hispanica and Pittosporum tobira

Leaves can specifically uptake trace elements from the surrounding environment. And tree leaves are a good biological indicator for air pollution. Therefore, chemical analysis of leaf specifications can be used to reproduce a historical record of air pollution. To better understand the history of urban air pollution from the 1920s to the 2020s in Nanjing, China, leaf samples of two woody plants, Platanus × hispanica and Pittosporum tobira, were collected in this study as environmental indicators from different historical periods. These included historical herbarium specimens and current leaves from live trees. The concentrations of 10 trace elements were determined in the samples using ICP‒MS. Pollution indices were calculated, yielding the key findings. The historical leaf samples showed continuously increasing mean concentrations of the 10 trace elements over time, which significantly correlating with automobile quantities and the number of large-scale industrial enterprises (p < 0.05). Moreover, modern leaf trace element concentrations were significantly correlated with PM10, PM2.5, automobiles, large-scale industrial enterprises, and atmospheric factors, confirming these as sources. In addition to the historical growth trend, spatial heterogeneity was revealed in historical Platanus × hispanica leaf samples from the 14 sites in Nanjing. Changes in heavy metal trace element pollution distributions were consistent with transportation and industrial expansion, with homologous patterns across elements. Specifically, post 1980s increases were observed in the representative NJ2 (Zhongshan Botanical Garden) and the NJ5(Nanjing University) sites, with higher concentrations occurring at in the NJ5 contaminated site than at the NJ2 uncontaminated site. After 2009, the 10 element (except Cd) pollution indices in Platanus × hispanica leaves fluctuated but declined overall. This reconstruction of Nanjing's air pollution history demonstrates that ample environmental information can be extracted from plant leaf markers over time and space.

The complexation of atmospheric Brown carbon surrogates on the generation of hydroxyl radical from transition metals in simulated lung fluid

Atmospheric particulate matter (PM) poses great adverse effects through the production of reactive oxygen species (ROS). Various components in PM are acknowledged to induce ROS formation, while the interactions among chemicals remain to be elucidated. Here, we systematically investigate the influence of Brown carbon (BrC) surrogates (e.g., imidazoles, nitrocatechols and humic acid) on hydroxyl radical (OH) generation from transition metals (TMs) in simulated lung fluid. Present results show that BrC has an antagonism (interaction factor: 20-90 %) with Cu2+ in OH generation upon the interaction with glutathione, in which the concentrations of BrC and TMs influence the extent of antagonism. Rapid OH generation in glutathione is observed for Fe2+, while OH formation is very little for Fe3+. The compositions of antioxidants (e.g., glutathione, ascorbate, urate), resembling the upper and lower respiratory tract, respond differently to BrC and TMs (Cu2+, Fe2+ and Fe3+) in OH generation and the degree of antagonism. The complexation equilibrium constants and site numbers between Cu2+ and humic acid were further analyzed using fluorescence quenching experiments. Possible complexation products among TMs, 4-nitrocatechol and glutathione were also identified using quadropule-time-of-flight mass spectrometry. The results suggest atmospheric BrC widely participate in complexation with TMs which influence OH formation in the human lung fluid, and complexation should be considered in evaluating ROS formation mediated by ambient PM.

A practical method for identifying key factors in the distribution and formation of heavy metal pollution at a smelting site

Smelting activities are the main pathway for the anthropogenic release of heavy metals (HMs) into the soil-groundwater environment. It is vital to identify the factors affecting HMs pollution to better prevent and manage soil pollution. The present study conducted a comprehensive investigation of HMs in soil from a large abandoned Zn smelting site. An integrated approach was proposed to classify and quantify the factors affecting HMs pollution in the site. Besides, the quantitative relationship between hydrogeological characteristics, pollution transmission pathways, smelting activities and HMs pollution was established. Results showed that the soils were highly contaminated by HMs with a pollution index trend of As > Zn > Cd > Pb > Hg. In identifying the pollution hotspots, we conclude that the pollution hotspots of Pb, As, Cd, and Hg present a concentrated distribution pattern. Geo-detector method results showed that the dominant driving factors for HMs distribution and accumulation were the potential pollution source and soil permeability. Additionally, the main drivers are variable for different HMs, and the interaction among factors also enhanced soil HMs contamination. Our analysis illustrates how the confounding influences from complex environmental factors can be distilled to identify key factors in pollution formation to guide future remediation strategies.

Health risk assessment of the European inhabitants exposed to contaminated ambient particulate matter by potentially toxic elements

PM₁₀-associated potential toxic elements (PTEs) can enter the respiratory system and cause health problems. In the current study, the health risk indices caused by PM₁₀ inhalation by adults, children, and infants in 158 European cities between 2013 and 2019 were studied to determine if Europeans were adversely affected by carcinogenic and non-carcinogenic factors or not. The Mann-Kendall trend test examined PM₁₀'s increasing or decreasing trend. Random Forest analysis was also used to analyse meteorological factors affecting PM₁₀ in Europe. Hazard quotient and cancer risk were estimated using PM₁₀-associated PTEs. Our results showed a decline in continental PM₁₀ concentrations. The correlation between PM₁₀ concentrations and temperature (-0.40), PBLH (-0.39), and precipitation were statistically strong (-0.21). The estimated Pearson correlation coefficients showed a statistically strong positive correlation between As & Pb, As & Cd, and Cd & Pb during 2013-2019, indicating a similar origin. PTEs with hazard quotients below one, regardless of subpopulation type, posed no noncancerous risk to Europeans. The hazard quotient values positively correlated with time, possibly due to elevated PTE levels. In our study on carcinogen pollution in Europe between 2013 and 2019, we found unacceptable levels of As, Cd, Ni, and Pb among adults, children, and infants. Carcinogenic risk rates were highest for children, followed by infants, adult women, and adult men. Therefore, besides monitoring and mitigating PM concentrations, effective control of PM sources is also needed.

Contribution and Effects of PM2.5-Bound Lead to the Cardiovascular Risk of Workers in a Non-Ferrous Metal Smelting Area Considering Chemical Speciation and Bioavailability

Lead is known to have toxic effects on the cardiovascular system. Owing to its high concentration, transmission range, and absorption efficiency in organisms, inhalation of fine particulate matter (PM2.5)-bound lead (PM2.5-Pb) may cause significant cardiovascular damage. However, the contribution and adverse effects of PM2.5-Pb on workers and residents in non-ferrous metal smelting areas are not fully understood. In this work, the concentration and chemical speciation of PM2.5-Pb were analyzed to determine its pollution characteristics at a typical non-ferrous metal smelting site. A panel study conducted among factory workers revealed that PM2.5-Pb exposure makes an important contribution to the human absorption of Pb. Although the chemical speciation of PM2.5-Pb suggested poor water solubility, a high bioavailability was observed in mice (tissue average value: 50.1%, range: 31.1-71.1%) subjected to inhalation exposure for 8 weeks. Based on the bioavailability data, the relationship between PM2.5-Pb exposure and cardiovascular damage was evaluated in animal simulation experiments. Finally, a damage threshold and cardiovascular-specific risk assessment model were established for the non-ferrous metal smelting area. Our project not only accurately estimates the risk of PM2.5-bound heavy metals on the cardiovascular system but also offers a scientific basis for future prevention and therapy of PM2.5-Pb-related diseases.

PAHs bound to submicron particles in rural Chinese homes burning solid fuels

Inhalation exposure to polycyclic aromatic hydrocarbons (PAHs) from indoor solid fuel combustion poses a high health risk, and PAHs bound to particles with smaller sizes (e.g., PM_1.0, aerodynamic diameter ≤ 1.0 µm) should be of particular concern since they can penetrate deep into pulmonary alveoli. However, PAHs bound to PM_1.0 was less studied compared with PAHs in total suspended particles or PM_2.5. In this study, multiple provincial field measurements were conducted to investigate 28 PAHs bound to PM_1.0 in rural Chinese homes. Daily averaged PM_1.0-PAH₂₈ concentrations ranged from 27 ng/m³ to 3795 ng/m³ (median: 233 ng/m³) and from 10 ng/m³ to 2978 ng/m³ (median: 87 ng/m³) in indoor and outdoor air, respectively. Higher concentrations were found in northern China in winter due to increased solid fuels consumption for space heating. The ambient pollution was lower during the non-heating season in Eastern China, where clean energy was preferred. Highly toxic congeners were more abundant in indoor air compared with outdoor air. The results of source apportionment revealed that solid fuel combustion was the primary contributor to rural household PM_1.0-PAHs, but other sources such as vehicles cannot be overlooked. The transition to cleaner energy can reduce the indoor PM_1.0-PAH₂₈ and BaP_eq-28 concentrations by 87% and 98%, respectively, and more efficient reduction was observed for highly toxic congeners. The estimated Incremental Lifetime Cancer Risk (ILCR) based on PM_1.0-PAH₂₈ ranged from 4.6 × 10^-5 to 3.4 × 10^-2, far exceeding the acceptable level of 10^-6. Over 60% of the ILCR could be attributed to inhalation exposure during childhood and adolescence.

Size distribution, meteorological influence and uncertainty for source-specific risks: PM2.5 and PM10-bound PAHs and heavy metals in a Chinese megacity during 2011-2021

This study aims at exploring size distribution, meteorological influence and uncertainty for source-specific risks of atmospheric particulate matter (PM), which can improve risk-mitigation strategies for health protection. Heavy metals (HMs) and polycyclic aromatic hydrocarbons (PAHs) in PM_2.5 and PM₁₀ were detected in a Chinese megacity during 2011-2021. A new method named as PMFBMR, which combines the Positive Matrix Factorization, Bootstrapping, Mote Carlo and Risk assessment model, was developed to estimate uncertainty of source-specific risks. It was found that PAH risks concentrated in fine PM, while HMs showed high risks in both fine and coarse PMs. For PM_2.5, HQ (non-cancer risk hazard quotient) of gasoline combustion (GC), diesel and heavy oil combustion (DC), coal combustion (CC), industrial source (IS), resuspended dust (RD) and secondary and transport PM (ST) were 0.6, 1.4, 0.9, 1.6, 0.3, and 0.3. ILCR (lifetime cancer risk) of sources were IS (9.2E-05) > DC (2.6E-05) = CC (2.6E-05) > RD (2.2E-05) > GC (1.7E-05) > ST (6.4E-06). PM_2.5 from GC, DC, CC and IS caused higher risks than coarse PM, while coarse PM from RD caused higher risks. Source-specific risks were influenced not only by emissions, but also by meteorological condition and dominant toxic components. Risks of GC and DC were usually high during stable weather. Some high risks of CC, IS and RD occurred at strong WS due to transport or wind-blown resuspension. GC and DC risks (influenced by both PAHs and HMs) showed strong relationship with T, while IS and RD risks (dominated by HMs) showed weak link with meteorological conditions. For uncertainty of source-specific risks, HQ and ILCR were sensitive for different variables, because they were dominated by components with different uncertainties. When using source-specific risks for risk-mitigation strategies, the focused toxic components, used toxic values, PM sizes and uncertainty are necessary to be considered.

Solubility of aerosol minor and trace elements in Xiamen Island, Southeast China: Size distribution, health risk and dry deposition

Aerosol element solubility is essential to evaluate the damage to the environment and human health. In this work, the size distribution of total and soluble elements in eight particle size ranges with diameter <0.25, 0.25-0.44, 0.44-1.0, 1.0-1.4, 1.4-2.5, 2.5-10, 10-16 and >16 μm was investigated in Xiamen Island, southeast China from March 2018 to June 2020. The results showed that both total and soluble elements exhibited significant size dependence without obvious seasonal variations, and their relative contributions to PM₁ mass were much lower than in particles larger than 1 μm. The correlations between some elements in soluble fraction were quite different from those in total fraction and the correlations also varied with particle size due to their different solubility. The solubility of Al, Fe, Ag and Cr was relatively low compared with other elements. Moreover, the solubility of Na, Mg, Ca, Mn and Ag was less dependent on particle size while Al, Fe and other trace elements exhibited the highest solubility in PM₁ and the lowest in PM_>10. Overall, the solubility of elements is primarily a function of aerosol origin and size. The carcinogenic risks of metal exposure via inhalation for children (3.31 × 10^-6) and adults (4.42 × 10^-6) were slightly higher than the guideline of cancer risk with >60 % from V. As for non-carcinogenic risk, the hazard index values for children and adults were 1.59 and 0.53, respectively, with Mn, V and Ni together accounting for >85 % of the risk. >85 % of the size-dependent dry deposition fluxes of the selected soluble elements over the Xiamen Bay were contributed by particles larger than 10 μm due to their high deposition velocities. The atmospheric inputs of bioavailable Fe and Cu to the sea exceeded the required amounts relative to inorganic nitrogen to meet the growth of phytoplankton.

Health risk assessment of particulate matter 2.5 in an academic metallurgy workshop

Exposure to indoor PM_2.5 is associated with allergies, eye and skin irritation, lung cancer, and cardiopulmonary diseases. To control indoor PM_2.5 and protect the health of occupants, exposure and health studies are necessary. In this study, exposure to PM_2.5 released in an academic metallurgy workshop was assessed and a health risk assessment was conducted for male and female students and technicians. Polycarbonate membrane filters and an active pump operating at a flow rate of 2.5 L/min were used to collect PM_2.5 from Monday to Friday for 3 months (August-October 2020) from 08:00-16:00. PM_2.5 mass concentrations were obtained gravimetrically, and the Multiple-Path Particle Dosimetry model was used to predict the deposition, retention, and clearance of PM_2.5 in the respiratory tract system. The risk of developing carcinogenic and non-carcinogenic effects among students and technicians was determined. The average PM_2.5 mass concentration for August was 32.6 μg/m³ 32.8 μg/m³ for September, and 32.2 μg/m³ for October. The head region accounted for the highest deposition fraction (49.02%), followed by the pulmonary (35.75%) and tracheobronchial regions (15.26%). Approximately 0.55 mg of PM_2.5 was still retained in the alveolar region 7 days after exposure. The HQ for male and female students was <1 while that of male and female technicians was >1, suggesting that technicians are at risk of developing non-carcinogenic health effects compared with students. The results showed a risk of developing carcinogenic health effects among male and female technicians (>1 × 10^-5 ); however, there was no excess cancer risk for students (<1 × 10^-6 ). This study highlights the importance of exposure and health studies in academic micro-environments such as metallurgy workshops which are often less researched, and exposure is underestimated. The results also indicated the need to implement control measures to protect the health of the occupants and ensure that the workshop rules are adhered to.

Seasonal variation of dissolved bioaccessibility for potentially toxic elements in size-resolved PM: Impacts of bioaccessibility on inhalable risk and uncertainty

The health effects of potentially toxic elements (PTEs) in airborne particulate matter (PM) are strongly dependent on their size distribution and dissolution. This study examined PTEs within nine distinct sizes of PM in a Chinese megacity, with a focus on their deposited and dissolved bioaccessibility in the human pulmonary region. A Multiple Path Particle Dosimetry (MPPD) model was used to estimate the deposited bioaccessibility, and an in-vitro experiment with simulated lung fluid was conducted for dissolved bioaccessibility. During the non-heating season, the dissolved bioaccessible fraction (DBF) of As, Cd, Co, Cr, Mn, Pb and V were greater in fine PM (aerodynamics less than 2.1 μm) than in coarse PM (aerodynamics between 2.1 and 10 μm), and vice versa for Ni. With the increased demand of heating, the DBF of Pb and As decreased in fine particle sizes, probably due to the presence of oxide/silicate compounds from coal combustion. Inhalation health risks based on the bioaccessible concentrations of PTEs displayed the peaks in <0.43 μm and 2.1-3.3 μm particulate sizes. The non-cancer risk was at an acceptable level (95th percentiles of hazard index (HI) was 0.49), but the cancer risk exceeded the threshold value (95th percentiles of total incremental lifetime cancer risk (TCR) was 8.91 × 10^-5). Based on the results of uncertainty analysis, except for the exposure frequency, the total concentrations and DBF of As and Cr in <0.43 μm particle size segment have a greater influence on the uncertainty of probabilistic risk.

Inhalation Bioaccessibility and Risk Assessment of Metals in PM2.5 Based on a Multiple-Path Particle Dosimetry Model in the Smelting District of Northeast China

PM2.5 can deposit and partially dissolve in the pulmonary region. In order to be consistent with the reality of the pulmonary region and avoid overestimating the inhalation human health risk, the bioaccessibility of PM2.5 heavy metals and the deposition fraction (DF) urgently needs to be considered. This paper simulates the bioaccessibility of PM2.5 heavy metals in acidic intracellular and neutral extracellular deposition environments by simulating lung fluid. The multipath particle dosimetry model was used to simulate DF of PM2.5. According to the exposure assessment method of the U.S. Environmental Protection Agency, the inhalation exposure dose threshold was calculated, and the human health risk with different inhalation exposure doses was compared. The bioaccessibility of heavy metals is 12.1−36.2%. The total DF of PM2.5 in adults was higher than that in children, and children were higher than adults in the pulmonary region, and gradually decreased with age. The inhalation exposure dose threshold is 0.04−14.2 mg·kg−1·day−1 for the non-carcinogenic exposure dose and 0.007−0.043 mg·kg−1·day−1 for the carcinogenic exposure dose. Cd and Pb in PM2.5 in the study area have a non-carcinogenic risk to human health (hazard index < 1), and Cd has no or a potential carcinogenic risk to human health. A revised inhalation health risk assessment may avoid overestimation.

Spatial characteristics of fine particulate matter in subway stations: Source apportionment and health risks

Air in subway stations is typically more polluted than ambient air, and particulate matter concentrations and compositions can vary greatly by location, even within a subway station. However, it is not known how the sources of particulate matter vary between different areas within subway stations, and source-specific health risks in subway stations are unclear. We analyzed the spatial characteristics of particulate matter by source and calculated source-specific health risks on subway platforms and concourses and in station offices by integrating source apportionment with health risk assessments. A total of 182 samples were collected in three areas in six subway stations in Nanjing, China. Enrichment factors and the positive matrix factorization receptor model were used to identify major sources. The carcinogenic and non-carcinogenic health risks to subway workers and passengers were evaluated to determine control priorities. Seven sources of particulate matter were identified in each area, with a total of four subway sources and six outdoor sources over all the areas. The source contributions to total element mass differed significantly from the source contributions to human health risks. Overall, subway sources contributed 48% of total element mass in the station office and 75% and 60% on the concourse and platform, respectively. Subway-derived sources accounted for 54%, 81%, and 71% of non-carcinogenic health risks on station platforms, concourses, and office areas, respectively. The corresponding values for carcinogenic risks were 51%, 86%, and 86%. Among the elements, cobalt had the largest contributions to carcinogenic and non-carcinogenic risks, followed by manganese for non-carcinogenic risks and hexavalent chromium for carcinogenic risks. Reducing emissions from subway sources could effectively protect the health of subway workers and passengers.

Metal particle seeding on urban surface samples

In order to estimate the resuspension of the particles empirically, it is necessary to carry out a homogeneous distribution of the particles on the tested surfaces. Thus, in many studies, seeding or deposition in experimental chambers is performed to quantify initial concentrations for subsequent resuspension experiments. The current study was carried out to assess metal particle seeding efficiency on four types of urban surfaces (slate, facade coating, tile, and glass) in a test chamber. To achieve this objective, we compared firstly different solubilization techniques of silver polydisperse particles (1.3-3.2 μm and 0.5-1.0 μm) and gold polydisperse particles (Ø˂5 μm) for chemical quantification by ICP-MS. The result showed better yields in the case of gold for all solubilization techniques studied (82% ± 5% to 98% ± 2% for gold versus 23% ± 18% to 84% ± 12% for silver). Based on this result, four seeding tests were carried out with the gold particles (distribution in chamber centered on 1μm). The concentrations seeded on urban surfaces (mean ± SD) varied from 10,900 ± 1,900 μg.m^-2 (facade coating sample) to 1900 ± 390 μg.m^-2 (glass sample). The relative standard deviation of the measured concentrations equaled 9.5% (tested for aluminum foils), which was less than the measurement uncertainty of the recording equipment (≈14%) and reflected good seeding homogeneity. Observations by scanning electron microscopy coupled to microanalysis (SEM-EDX) were in agreement with these conclusions.

Sources of airborne particulate matter-bound metals and spatial-seasonal variability of health risk potentials in four large cities, South Korea

Fifteen airborne particulate matter-bound metals were analyzed at 14 sites in four large cities (Seoul, Incheon, Busan, Daegu) in South Korea, between August 2013 and June 2017. Among the seven sources resolved by positive matrix factorization, soil dust and marine aerosol accounted for the largest and second largest portions in the three cities; however, in Seoul, soil dust and traffic occupied the largest and the second largest, respectively. Non-carcinogenic risk assessed by inhalation of eight metals (Cd, Co, Ni, Pb, As, Al, Mn, and V) was greater than the hazard index (HI) of 1 at four sites located at or near the industrial complexes. Cumulative incremental lifetime cancer risk (ILCR) due to exposure to five metals (Cd, Co, Ni, Pb, and As) exceeded the 10^-6 cancer benchmark at 14 sites and 10^-5 at six sites, which includes four sites with HI greater than 1. The largest contributor to ILCR was coal combustion in Seoul, Incheon, and Daegu, and industry sources in Busan. Moreover, industry sources were the largest contributors to non-carcinogenic risk in Seoul, Busan, and Daegu, and soil dust was in Incheon. Incheon had the highest HI in spring because of the higher contribution of soil dust sources than in other seasons. The higher ILCR in Incheon in spring and winter and higher ILCR and HI in Daegu in autumn were mainly due to the influence of industry or coal combustion sources. Statistically significant differences in the ILCR and HI values among the sampling sites in Busan and Daegu resulted from the higher contribution of industry sources at a certain site in the respective city.

Oxidative potential and water-soluble heavy metals of size-segregated airborne particles in haze and non-haze episodes: Impact of the "Comprehensive Action Plan" in China

Air pollution is a major environmental health challenge in megacities, and as such a Comprehensive Action Plan (CAP) was issued in 2017 for Beijing, the capital city of China. Here we investigated the size-segregated airborne particles collected after the implementation of the CAP, intending to understand the change of oxidative potential and water-soluble heavy metal (WSHM) levels in 'haze' and 'non-haze' days. The DNA damage and the levels of WSHM were analyzed by Plasmid Scission Assay (PSA) and High-Resolution Inductively Coupled Plasma Mass Spectrometry (HR-ICP-MS) techniques. The PM mass concentration was higher in the fine particle size (0.43-2.1 μm) during haze days, except for the samples affected by mineral dust. The particle-induced DNA damage caused by fine sized particles (0.43-2.1 μm) exceeded that caused by the coarse sized particles (4.7-10 μm). The DNA damage from haze day particles significantly exceeded those collected on non-haze days. Prior to the instigation of the CAP, the highest value of DNA damage decreased, and DNA damage was seen in the finer size (0.43-1.1 μm). The Pearson correlation coefficient between the concentrations of water-soluble Pb, Cr, Cd and Zn were positively correlated with DNA damage, suggesting that these WSHM had significant oxidative potential. The mass concentrations of water-soluble trace elements (WSTE) and individual heavy metals were enriched in the finer particles between 0.43 μm to 1.1 μm, implying that smaller sized particles posed higher health risks. In contrast, the significant reduction in the mass concentration of water-soluble Cd and Zn, and the decrease of the maximum and average values of DNA damage after the CAP, demonstrated its effectiveness in restricting coal-burning emissions. These results have demonstrated that the Beijing CAP policy has been successful in reducing the toxicity of 'respirable' ambient particles.

Characteristics of fine particulate matter (PM2.5) at Jinsha Site Museum, Chengdu, China

Air pollution is a serious threat to ancient sites and cultural relicts. In this study, we collected indoor and outdoor PM_2.5 samples and individual particles at the Exhibition Hall of Jinsha Site Museum in June 2020, and then the chemical components, sources, morphology, and mixing state of the fine particulate matter were analyzed. Our results show that the indoor and outdoor PM_2.5 concentrations at the Exhibition Hall were 33.3±6.6 and 39.4±11.4 μg m^-3, respectively. Although the indoor and outdoor concentrations of OC and EC were close, the proportion of secondary organic carbon in OC outdoor (33%) was higher than that indoor (27%). The PM_2.5 was alkaline both indoors and outdoors, and the outdoor alkalinity was stronger than the indoor alkalinity. SNA (SO₄^2-, NO₃^-, and NH₄⁺) was the dominant component in the water-soluble inorganic ions; Na⁺, Mg²⁺, and Ca²⁺ were well correlated (R²> 0.9), and Cl^- and K⁺ were also highly correlated (R²> 0.8). Enrichment factor analysis showed that Cu (indoor) and Cd were the main anthropogenic elements and that Cd was heavily enriched. Principal components analysis showed that the main sources of PM_2.5 at Jinsha Site Museum were motor vehicles, dust, secondary sources, and combustion sources. The individual particles were classified as organic matter, S-rich, soot, mineral, and fly ash/metal particles, and most of these particles were internally mixed with each other. At last, we proposed pollution control measures to improve the air quality of museums and the preservation of cultural relicts.

Potential health risks of inhaled toxic elements and risk sources during different COVID-19 lockdown stages in Linfen, China

Levels of toxic elements in ambient PM_2.5 were measured from 29 October 2019 to 30 March 2020 in Linfen, China, to assess the health risks they posed and to identify critical risk sources during different periods of the COVID-19 lockdown and haze episodes using positive matrix factorization (PMF) and a health-risk assessment model. The mean PM_2.5 concentration during the study period was 145 μg/m³, and the 10 investigated toxic elements accounted for 0.31% of the PM_2.5 mass. The total non-cancer risk (HI) and total cancer risk (TCR) of the selected toxic elements exceed the US EPA limits for children and adults. The HI for children was 2.3 times that for adults for all periods, which is likely due to the high inhalation rate per unit body weight for children. While the TCR for adults was 1.7 times that of children, which is mainly attributed to potential longer exposure duration for adults. The HI and TCR of the toxic elements during full lockdown were reduced by 66% and 58%, respectively, compared to their pre-lockdown levels. The HI and TCR were primarily attributable to Mn and As, respectively. Health risks during haze episodes were significantly higher than the average levels during COVID-19 lockdowns, though the HI and TCR of the selected toxic elements during full-lockdown haze episodes were 68% and 17% lower, respectively, than were the levels during pre-lockdown haze episodes. During the study period, fugitive dust and steel-related smelting were the highest contributors to HI and TCR, respectively, and decreased in these emission sources contributed the most to the lower health risks observed during the full lockdown. There, the control of these sources is critical to effectively reduce public health risks.

Deposition of ambient particles in the human respiratory system based on single particle analysis: A case study in the Pearl River Delta, China

It is important to evaluate how ambient particles are deposited in the human respiratory system in view of the adverse effects they pose to human health. Traditional methods of investigating human exposure to ambient particles suffer from drawbacks related either to the lack of chemical information from particle number-based measurements or to the poor time resolution of mass-based measurements. To address these issues, in this study, human exposure to ambient particulate matter was investigated using single particle analysis, which provided chemical information with a high time resolution. Based on single particle measurements conducted in the Pearl River Delta, China, nine particle types were identified, and EC (elemental carbon) particles were determined to be the most dominant type of particle. In general, the submicron size mode was dominant in terms of the number concentration for all of the particle types, except for Na-rich and dust particles. On average, around 34% of particles were deposited in the human respiratory system with 13.9%, 7.9%, and 12.6% being distributed in the head, tracheobronchial, and pulmonary regions, respectively. The amount of Na-rich particles deposited was the highest, followed by EC. The overall deposition efficiencies of the Na-rich and dust particles were higher than those of the other particle types due to their higher efficiencies in the head region, which could be caused by the greater sedimentation and impaction rates of larger particles. In the head region, the Na-rich particles made the largest contribution (30.5%) due to their high deposition efficiency, whereas in the tracheobronchial and pulmonary regions, EC made the largest contribution due to its high concentration. In summary, the findings of this initial trial demonstrate the applicability of single particle analysis to the assessment of human exposure to ambient particles and its potential to support traditional methods of analysis.

Human health-risk assessment based on chronic exposure to the carbonyl compounds and metals emitted by burning incense at temples

Health effects resulting from the smoke of carbonyl compounds (aldehydes and ketones) and metal-containing incense particles at temples during incense burning periods were evaluated at temple A (without incense reduction activities) and B (with incense reduction activities), Nantou County, in 2018. The predominant size fractions of particles were PM₁, PM_1-2.5, and PM_2.5-10 at both temples. The total particle mass at temple A was approximately 1.1 times that of temple B due to incense reduction at temple B. The most abundant metal elements in all particle size fractions at both temples were Fe, Al, and Zn. Metal species of incense smoke are divided into three groups by hierarchical cluster analysis and heatmaps, showing higher metal contents in groups PM₁, PM_18-10, and PM_18-2.5 at temple A. In contrast, higher metal contents were observed in PM_18-10 and PM_2.5-1 at temple B. Most of the carbonyl species were formaldehyde and acetaldehyde, released during incense burning periods, with concentrations ranging from 6.20 to 13.05 μg/m³ at both temples. The total deposited fluxes of particle-bound metals at temples A and B were determined to be 83.00% and 84.82% using the International Commission on Radiological Protection (ICRP) model. Health-risk assessments revealed that the risk values of metals and carbonyls were above recommended guidelines (10^-6) at temple A. Since worshippers and staff are exposed to incense burning environments with poor ventilation over a long period, these toxic organic compounds and metals increase health risks in the respiratory tract. Therefore, incense reduction is important to achieve healthy temple environments.

Characteristics, emission sources and health risk assessment of trace elements in size-segregated aerosols during haze and non-haze periods at Ningbo, China

To characterize trace elements from inhalable particles and to estimate human health risks, airborne particles at an urban area of Ningbo city during haze and non-haze periods from November 2013 to May 2014 were collected by a nine-stage sampler. Seventeen trace elements (Na, Mg, Al, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Cd and Pb) were measured by inductively coupled plasma mass spectrometry (ICP-MS). The concentrations of trace elements are in the ranges of 0.51 ng m^-3 (Co) ~ 1.53 µg m^-3 (K) for fine particles (Dp < 2.1 μm), and 1.07 ng m^-3 (Co) ~ 4.96 µg m^-3 (K) for coarse particles (2.1 μm < Dp < 9.0 μm) during the haze days, which are 1.15 -4.30 and 1.23- 7.83-fold as those of non-haze days, respectively. These elements could be divided into crustal elements (Na, Mg, Al, Ca, Ti, Fe and Co), non-crustal elements (Cu, Zn, Cd and Pb) and mixed elements (K, V, Cr, Mn, Ni and As) according to their enrichment factor values (EFs) and size distribution characteristics. Five emission sources of trace elements were identified by positive matrix factorization (PMF) modeling. The main sources of trace elements in fine particles are traffic emission (21.7%), coal combustion (23.6%) and biomass burning (32.1%); however, soil dust (61.5%), traffic emission (21.9%) and industry emissions (11.8%) are the main contributors for coarse particles. With the help of the multiple-path particle dosimetry (MPPD) model, it was found that deposition fractions of seventeen measured elements in the pulmonary region were in the range of 12.4%-15.1% and 6.66% -12.3% for the fine and coarse particles, respectively. The human health risk assessment (HRA) was employed according to the deposition concentration in the pulmonary region. The non-carcinogenic risk (HI) was below the safety limit (1.00). Nonetheless, the excess lifetime carcinogenic risk (ELCR) for adults increased by 2.42-fold during the haze days (2.06 × 10^-5) as compared to that of non-haze days (8.50 × 10^-6) in fine particles. Cr (VI) and As together contributed 96.5% and 96.3% of the integrated cancer risks during the haze and non-haze periods, respectively. Moreover, the related ELCR values in coarse particles were 36.7% and 62.8% of those in the fine particles for the non-haze period and haze period, respectively.

Size distributions and health risks of particle-bound toxic elements in the southeast coastland of China

Size-fractionated samples were collected at five coastal urban sites in Fujian Province, southeast China, in 2016 and 2017 to determine the trace elements using ICP-MS. Ca, Fe, Al, Mg, and K were the most abundant elements among the studied elements in TSP, much higher than those of heavy metals. The annual mean concentrations of Pb, As, V, Ni, Cd, and Mn were within the acceptable limits of the World Health Organization and the Ministry of Ecology and Environment of China while Cr(VI) exceeded the limits. Most elements exhibited clear seasonal patterns with maxima over the cold season and minima over the warm season. The spatial variabilities in concentrations of the measured elements were not significant except Ni and V. However, the size distribution pattern of each element was quite similar across the region. Characteristic size distributions of elements allowed identification of three main groups: (a) unimodal distribution in the coarse fraction for Ca, Al, Mg, and Ba; (b) unimodal distribution in the fine fraction for Pb, Se, As, Ag, V, Ni, Zn, and Cd; and (c) bimodal or multimodal distribution for Fe, Mn, Cr, K, and Cu. The combination of the size-fractionated concentrations, enrichment factors, correlation coefficients, and factor analysis offered the identification of mixed sources such as vehicular exhaust and wear, heavy fuel oil combustion, and resuspension of road dust. Non-carcinogenic health risks associated with inhalable exposure to airborne metals were higher than the safety threshold (hazard index > 1) across the region, suggesting non-carcinogenic health risks via inhalation. Mn, V, and Ni contributed 74-83% of the total non-carcinogenic risk. The assessment investigation of carcinogenic health risks revealed V and Cr(VI) as elements with the largest carcinogenic risks, accounting for more than 95% of the overall inhalation risk. Nevertheless, the carcinogenic risks for children and adults were between 10^-6 and 10^-4, within the range considered acceptable by the US EPA. In terms of the size-fractionated risk, PM_2.5 contributed 43-50% and 39-44% of the total non-carcinogenic and carcinogenic risks, respectively, indicating the potential health hazard of coarse particle-bound toxic metals was not negligible.

Face masks effectively limit the probability of SARS-CoV-2 transmission

Airborne transmission by droplets and aerosols is important for the spread of viruses. Face masks are a well-established preventive measure, but their effectiveness for mitigating SARS-CoV-2 transmission is still under debate. We show that variations in mask efficacy can be explained by different regimes of virus abundance and related to population-average infection probability and reproduction number. For SARS-CoV-2, the viral load of infectious individuals can vary by orders of magnitude. We find that most environments and contacts are under conditions of low virus abundance (virus-limited) where surgical masks are effective at preventing virus spread. More advanced masks and other protective equipment are required in potentially virus-rich indoor environments including medical centers and hospitals. Masks are particularly effective in combination with other preventive measures like ventilation and distancing.

Size distributions of source-specific risks of atmospheric heavy metals: An advanced method to quantify source contributions to size-segregated respiratory exposure

Heavy metals in size-segregated particulate matter (PM) were investigated in a Chinese megacity, and an advanced model was developed to quantify source-specific risks focusing on size-segregated respiratory exposure. Incremental lifetime cancer risk (ILCR) and non-cancer risk (hazard quotient: HQ) based on deposition concentrations of heavy metals displayed a peak at 4.7-5.8 µm. The percentage contributions to cancer risk were as follows: industrial emission (IE, 34%) > secondary and transport (ST, 29%) > resuspended dust (RD, 21%) > coal combustion (CC, 11%) > traffic emission (TE, 4%) during spring and summer (SS), and CC (31%) > ST (26%) > IE (21%) > RD (11%) ≈ TE (11%) during autumn and winter (AW). RD (41% of HQ during SS, 28% during AW) and IE (45% of HQ during SS, 35% during AW) dominated non-cancer risk. ILCR and HQ of CC were high at sizes 1.1-2.1 µm and 0.43-0.65 µm; those of RD were high at sizes > 3.3 µm; and those of IE were bimodal at fine (<2.1 µm) and coarse (>2.1 µm) sizes, respectively. Cancer risk was more susceptible to small particles than non-cancer risk, partly because higher ILCR was from CC, but higher HQ was attributed by RD.

The characteristics of atmospheric particles and metal elements during winter in Beijing: Size distribution, source analysis, and environmental risk assessment

In order to investigate the pollution characteristics of size-segregated particles and metal elements (MEs) after the Chinese Air Pollution Prevention Action Plan was released in 2013, an intensive field campaign was conducted in the suburban area of Chaoyang District, Beijing in winter 2016. The size distributions of particle mass concentrations were bimodal, with the first peak in the fine fraction (0.4-2.1 µm) and the second peak in the coarse fraction (3.3-5.8 µm). Moreover, the proportion of fine particles increased and the proportion of coarse particles decreased as the pollution level was more elevated. It was found that the composition of coarse particles is as important as that of fine particles when pollution of aerosol metals in the atmosphere in 2016 were compared to 2013. In addition, according to the size distribution characteristics, 23 MEs were divided into three groups: (a) Fe, Co, Sr, Al, Ti, Ba, and U, which concentrated in coarse mode; (b) Zn, As, Cd, Tl, and Pb, which concentrated in fine mode; and (c) Na, K, Be, V, Cr, Mn, Ni, Cu, Mo, Ag, and Sn, showing bimodal distribution. Under clean air, slight pollution and moderate pollution conditions, most elements maintained their original size distributions, while under severe pollution, the unimodal distributions of most MEs became bimodal distributions. The factors analysis combined with size distributions indicated that Na, Zn, Mo, Ag, Cd, and Tl, showing the moderate to severe contamination on environment, were significantly influenced by diffuse regional emissions or anthropogenic source emissions (vehicle exhaust emissions and combustion process). The environmental risk assessment revealed that the heavy metal loading in the atmospheric particles collected had a high potential for ecological risk to the environment during sampling period because of the high contribution of Cd, Tl, Zn and Pb.

Fine and coarse particulate matter, trace element content, and associated health risks considering respiratory deposition for Ergene Basin, Thrace

Ergene Basin is located in Thrace, Turkey, where industries are densely populated. This study aimed to determine exposure of people living in Ergene Basin (Çorlu and Çerkezköy) to fine and coarse PM, and its potentially toxic element (PTE) content by considering variation in respiratory airway deposition rates with daily activities and PM particle size by employing deposition models of International Commission on Radiological Protection and Multiple Path Particle Dosimetry. Fine and coarse PM samples were collected daily for a year at points in Çorlu and Çerkezköy representing urban and industrial settings, respectively. A questionnaire survey was conducted in the study area to obtain time-activity budgets, and associated variation was included in the health risk assessment by considering time-activity-dependent inhalation rates. The studied PTEs were Al, As, Ba, Cd, Cr, Co, Mn, Ni, Pb, and Se. The mean fine and coarse PM concentrations were measured as 23 and 14 μg/m³ in Çorlu, and 22 and 12 μg/m³ in Çerkezköy, respectively. The only PTE that exceeded acceptable risk in terms of total carcinogenic risk was Cr. Non-carcinogenic risks of all the PTEs including Cr were below the threshold. The use of deposition fractions in the health risk assessment (HRA) calculations was found to prevent overestimation of health risks by at least 91% and 87% for fine and coarse PM, respectively, compared to the regular HRA. Minor differences in risk between Çorlu and Çerkezköy suggest that urban pollution sources could be at least as influential on human health as industrial sources.

Trace Element Contamination in One of the Yangtze Tributaries (Hunan, China)—Source Review and Potential Release from Sediments

Spatio-temporal distribution and leachability of some trace elements (TE) were investigated in sediments of the Xiangjiang River, tributary of the Yangtze River. Based on data collected during 2015–2017, a literature review and geoaccumulation indexes, the pollution level was the highest for Cd, Sb and Hg (Igeo > 3). Over the period reviewed, the TE contamination level displayed almost no temporal variation but an obvious spatial distribution. The most upstream contamination hotspot (Cd > Cr > As, Cu, Pb, Zn > Hg, Sb) was the Songbai section. This hotspot did not spread further downstream. The second hotspot identified was the Zhuzhou–Xiangtan section, impacted by Cd > Hg, Pb, Zn > Cu, with the Zhuzhou area being particularly highly impacted by Pb and Zn. A 30-day leaching experimental protocol under aerobic and anaerobic conditions was carried out to access TE mobility. Low percentages of TE released were calculated, showing that the TE fate mostly depends on the stability of bearing phases under specific physicochemical and microbial conditions. In this case, the studied sediments can be an important sink for these TE. However, some environmental issues have to be considered as some leachate concentrations of contaminants (As, Cr, Cu and U) released into water exceed freshwater aquatic life criteria.

Characteristics of heavy metals in size-fractionated atmospheric particulate matters and associated health risk assessment based on the respiratory deposition

The heavy metal distributions in size-fractionated atmospheric particulate matters and the associated health risks were investigated in a typical mining and smelting area in Southwest China. The Cd, Cr, Cu, Pb, and Zn concentrations were 19.28, 44.48, 100.0, 554.0, and 601.8 ng/m³, respectively, in PM_2.1; and 23.45, 60.99, 95.25, 559.3, and 813.7 ng/m³, respectively, in PM₁₀. Enrichment factors of heavy metals indicated that anthropogenic sources of Cd, Cu, Pb, and Zn in the size-fractionated particles. The elevated concentrations of Cd, Cu, Pb, and Zn were dominantly enriched in submicron particles (D_P < 1.1 μm), whereas Cr tended to be accumulated in coarse particles (2.1 < D_P < 10 μm). The deposition concentrations for multiple heavy metals in the head airway region, tracheobronchial region, and alveolar regions were 321.07, 21.58, and 51.96 ng/h for children, and 634.49, 42.65, and 102.68 ng/h for adults, respectively. The coarse particles contributed the most to the deposition concentration of HMs in head region, whereas submicron particles had relative higher proportions in the alveolar region. Heavy metals, especially Pb, caused noncarcinogenic risk to the children as the hazard index was 4.45. Moreover, total carcinogenic risks of heavy metals (Cr, Cd, and Pb) were 4.33 × 10^-5 and 7.58 × 10^-5 for adults and children, respectively, indicating potential carcinogenic risks. Overall, the results of this study revealed high health risks to the residents living around the mining and smelting areas, especially the children. It was therefore urgent to control the emission of heavy metals in the atmosphere.

Chemical characteristics and health risk assessment of potential toxic elementsin atmospheric PM10 around Ashaka cement factory, Gombe, Nigeria

The study determined the ambient mass concentrations, chemical composition and health risks associated with PM10 around Ashaka cement factory, Gombe, Nigeria. The samples were collected for the period (2019-2020). A total of 60 PM10 samples were collected and analyzed for seventeen elements using Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES). The data collected were analyzed for descriptive and inferential statistics. The health risk was analyzed for hazard quotient (HQ), hazard index (HI) and cancer risk (CR). The average annual PM10 mass concentrations were found to be higher than the annual limit value for air quality standards (40 μgm-3). The HI estimated were >1 for children, while CR values of Cd, Ni, As and Cr for children and Cr for adults were higher than the acceptable value 10-6, indicating children are more probable to develop cancer than adults.

Size distributions of particle-generated hydroxyl radical (·OH) in surrogate lung fluid (SLF) solution and their potential sources

Although it is known that increases in ambient particulate matter (PM) levels are associated with elevated occurrence of adverse health outcomes, the understanding of the mechanisms of PM-related health effects is limited by our knowledge of how particle size and composition are altered subsequent to inhalation through respiratory-deposited processing. Here we present a particle-generated hydroxyl radical (·OH) study of the size-resolved particles as particles are inhaled in the human respiratory tract (RT), and we show that accumulation-mode particles are significant factors (71-75%) in ·OH generation of lung-deposited particles using Multiple-Path Particle Dosimetry (MPPD) model. The ability of PM to catalyze ·OH generation is mainly related to transition metals, particularly towards the upper regions of the RT (75%), and to quinones deeper in the lung (42-46%). Identification of this generation ability induced by chemical composition has shown that four potential sources (biomass burning, incomplete combustion, mobile & industry, and mineral dust) are responsible for ·OH generation. With ·OH-forming ability after PM inhalation implicated as the first step towards revealing the subsequent toxic processes, this work draws a connection between the detailed ·OH chemistry occurring on size-resolved particles and a possible toxicological mechanism based on chemical composition and sources.

Assessment of Elemental Components in Atmospheric Particulate Matter from a Typical Mining City, Central China: Size Distribution, Source Characterization and Health Risk

Atmospheric particulate matters in nine size fractions were sampled at Huangshi city, Hubei province. Elemental concentrations occurred unimodal size distribution for Zn, Pb and Ni, dimodal distribution for Ca, S, Fe and Ti, and trimodal distribution for Cl, K, Mn, Cu and Cr. Enrichment factor and principal component analysis identified the main sources from crustal material, biomass burning, waste incineration, vehicular and industrial emission. As for the non-carcinogenic health risk through inhalation, there were certain potential risks for Mn and Sb for children, and Pb for children and adults in PM_2.5. It showed certain potential risks for Mn, Sb and Pb for children and adults in PM₁₀. As for the carcinogenic health risk through inhalation, Cr in PM_2.5 and Ni, Co and Cr in PM₁₀ indicated unacceptable risk for children and adults. Meanwhile, Co and Ni in PM_2.5 represented acceptable risk for children.

Chemical compositions and source apportionment of PM2.5 during clear and hazy days: Seasonal changes and impacts of Youth Olympic Games

Seasonal changes in chemical compositions and source apportionment of PM_2.5 during clear and hazy days help to develop effective control policy, but limited information is available in megacity Nanjing. In this study, 102 PM_2.5 samples were collected during clear and hazy days from 4 seasons in 2014-2015. Their chemical compositions (organic and elemental carbon, 8 water-soluble ions, and 22 inorganic elements) were determined, which were used for PM_2.5 source apportionment using the PMF model. The mean PM_2.5 concentration was lower during clear days than hazy days (42 vs. 122 μg m^-3), so were mean concentrations of metals (0.48 vs. 0.82 ng m^-3 for Co and 2.0 vs. 2.4 μg m^-3 for Na), water soluble ions (0.10 vs. 0.16 μg m^-3 for Mg²⁺ and 12 vs. 23 μg m^-3 for SO₄^2-), and carbon species (3.2 vs. 5.4 μg m^-3 for elemetal C and 20 vs. 35 μg m^-3 for organic C). Based on the PMF model, five main sources of PM_2.5 were identified including secondary aerosols (31%), coal combustion (27%), road & construction dust (26%), oil combustion (8.5%), and iron & steel industry (5.1%) for all samples. The PM_2.5 concentrations from the 5 sources were 0.01-46.5, averaging 9.8 μg m^-3 during clear days (PM_2.5 < 75 μg m^-3), which increased to 1.83-60.1, averaging 18 μg m^-3 during hazy days. However, based on their contributions to PM_2.5, only secondary aerosols increased during hazy days compared to clear days in all seasons (11 vs. 42%), indicating its dominant contribution to haze in Nanjing. For different seasons, road & construction dust was a major contributor to PM_2.5 in the summer, while oil combustion (4.86 vs.16.8%) contributed more in spring. However, coal combustion became the main source of PM_2.5 during the summer (44-85%) due to the pollution controls for the Youth Olympic Games. Our results suggest that secondary aerosols play an important role in haze formation and season-dependent pollution measures should be implemented for effective control of air pollution.

Particle-induced oxidative damage by indoor size-segregated particulate matter from coal-burning homes in the Xuanwei lung cancer epidemic area, Yunnan Province, China

Size-segregated samples of airborne particulate matter were collected at the coal-burning homes of the Hutou high lung cancer epidemic village and a comparison site Xize village of the Xuanwei County, Yuanan Province, by an Anderson Cascade Impact Sampler in winter and spring to study the toxicological characteristics of different-sized particles. The DNA damage caused by the water-soluble fractions of these size-segregated particles was analyzed by the plasmid scission assay, and the trace element compositions were determined by Inductively Coupled Plasma Mass Spectrometry. The DNA damage rate from the airborne particles in the high lung cancer incidence area was higher than that in Xize village. The different-sized particles have highly varying DNA damage rates, with the values being greater in the small size range than in the large size range. The particle-induced DNA damage rates had a significantly positive correlation with total water-soluble trace elements. Further analysis of the individual elements indicated that the water-soluble heavy metals Zn, Cu, Cd, Rb, Cs, and Sb had a positive correlation with the particle-induced DNA damage, implying that these water-soluble heavy metals played an important role in the DNA damage. The Sr had a negative correlation with the particle-induced DNA damage, suggesting that the water-soluble Sr might counter DNA damage. The mass concentrations of the total and individual water-soluble trace elements were mostly enriched in the small particle size ranges, thus implying the indoor airborne particles in the small size ranges would have a higher health risk.

Specific sources of health risks caused by size-resolved PM-bound metals in a typical coal-burning city of northern China during the winter haze event

High particulate matter (PM) pollution frequently occurs in winter over northern China , resulting in threats to human health. To date, there are limited studies to link source apportionments and health risk assessments in the different size-resolved PM samples during high PM events. In this study, size-segregated PM samples were collected in Linfen, a typical coal-burning city, in northern China during a wintertime haze pollution. In addition to water-soluble ions and carbon contents, metallic elements in the different size-segregated PM samples were also determined for health risk assessments by inhalation of PM. During the sampling period, the average concentration of PM₁₀ was 274 ± 57 μg m^-3 with a major fraction (73%) of organic material and secondary-related aerosols, and an insignificant portion of trace elements (TEs, ~ 3%). The size distribution showed that As and Se, markers of coal combustion, exhibited a mono-modal distribution with a major peak at 0.4-0.7 μm and the others mostly possessed mono-/bi-modal patterns with a major peak at 3.3-5.8 μm. The cancer risk (CR) resulted from PM₁₀ metals by inhalation was estimated to be 2.91 × 10^-5 for children and 7.75 × 10^-5 for adults while non-cancer risk (NCR) was 2.10 for children and 0.70 for adults. Chromium (Cr) was the dominant species (~89%) of cancer risk in PM₁₀. Road dust was a major fraction (~65%) to total metals in coarse PM (dp > 3.3 μm) whereas coal combustion was a dominant source (~55%) in submicron (dp < 1.1 μm) PM metals. However, traffic emissions (40%) and coal combustion (36%) were the dominant sources of CR since both emissions contributed major fractions (74%) to Cr, especially in submicron PM which exhibited high deposition efficiency of TEs into respiratory tracts, resulting in high CR in Linfen City.

Assessment of indoor air exposure at residential homes: Inhalation dose and lung deposition of PM10, PM2.5 and ultrafine particles among newborn children and their mothers

Accurate assessment of particulate matter (PM) dose and respiratory deposition is essential to better understand the risks of exposure to PM and, consequently, to develop the respective risk-control strategies. In homes, this is especially relevant in regards to ultrafine particles (UFP; <0.1 μm) which origin in these environments is mostly due to indoor sources. Thus, this study aimed to estimate inhalation doses for different PM mass/number size fractions (i.e., PM₁₀, PM_2.5 and UFP) in indoor air of residential homes and to quantify the deposition (total, regional and lobar) in human respiratory tract for both newborn children and mothers. Indoor real-time measurements of PM₁₀, PM_2.5 and UFP were conducted in 65 residential homes situated in Oporto metropolitan area (Portugal). Inhalation doses were estimated based on the physical characteristics of individual subjects and their activity patterns. The multi-path particle dosimetry model was used to quantify age-specific depositions in human respiratory tract. The results showed that 3-month old infants exhibited 4-fold higher inhalation doses than their mothers. PM₁₀ were primarily deposited in the head region (87%), while PM_2.5 and UFP depositions mainly occurred in the pulmonary area (39% and 43%, respectively). Subject age affected the pulmonary region and the total lung deposition; higher deposition being observed among the newborns. Similarly, lower lobes (left lobe: 37% and right lobe: 30%) received higher PM deposition than upper and middle lobes; right lobes lung are prone to be more susceptible to respiratory problems, since asymmetric deposition was observed. Considering that PM-related diseases occur at specific sites of respiratory system, quantification of site-specific particle deposition should be predicted in order to better evidence the respective health outcomes resulting from inhaled PM.

Chemical content and source apportionment of 36 heavy metal analysis and health risk assessment in aerosol of Beijing

The concentration levels of 36 airborne heavy metals and atmospheric radioactivity in total suspended particulate (TSP) samples were measured to investigate the chemical characteristics, potential sources of aerosols, and health risk in Beijing, China, from September 2016 to September 2017. The TSP concentrations varied from 6.93 to 469.18 μg/m³, with a median of 133.97 μg/m³. The order for the mean concentrations of heavy metals, known as hazardous air pollutants (HAPs), was as follows: Mn > Pb > As > Cr > Ni > Se > Cd > Co > Sb > Hg > Be; Non-Designated HAPs Metals: Ca > Fe > Mg > Al > K > Na > Zn > P > Ba > Ti > Cu > Sr > B > Sn > I > V > Rb > Ce > Mo > Cs > Th > Ag > U > Pt. The median concentration of As was higher than China air quality standard (6 ng/m³). The gross α and β concentration levels in aerosols were (1.84 ± 1.59) mBg/m³ and (1.15 ± 0.85) mBg/m³, respectively. The enrichment factor values of Cu, Ba, B, Ce, Tl, Cs, Pb, As, Cd, Sb, Hg, Fe, Zn, Sn, I, Mo, and Ag were higher than 10, which indicated enriched results from anthropogenic sources. Pb, As, and Cd are considered to originate from multiple sources; fireworks released Ba during China spring festival; Fe, Ce, and Cs may come from stable emissions such as industrial gases. The health risks from anthropogenic metals via inhalation, ingestion, and dermal pathway were estimated on the basis of health quotient as well as the results indicated that children faced the higher risk than adults during the research period. For adults, the health risk posed by heavy metals in atmospheric particles was below the acceptable level.

Characteristics and risk assessments of heavy metals in fine and coarse particles in an industrial area of central China

In order to investigate the pollution level and chemical form transformation characteristics of heavy metals, atmospheric fine particles and coarse particles were collected in an urban industrial area of Zhuzhou City in central China during winter and summer. The results indicated that PM_2.5 and PM₁₀ all showed similar time variation, with the highest concentration in winter (112.1 μg/m³, 210.3 μg/m³) and the lowest concentration in summer (44.4 μg/m³, 81.0 μg/m³), respectively. As for heavy metals carried by atmospheric particles, only Cu had similar time variation with particle concentration and was mainly in oxidisable fraction. Zn, Pb and Cd were chiefly distributed in acid-extractable fraction, and Zhuzhou City was extremely polluted by these three heavy metals which mainly came from Qingshui Pond Industrial Area. Moreover, risk assessment results indicated that this area had high ecological risks on the environment and potential non-carcinogenic health effects and low carcinogenic risk to human health, especially for children. In addition, leaching test of atmospheric particles showed that the releasing of heavy metals in simulated acid rain primarily came from acid-extractable fraction, especially in winter, and the chemical form transformation followed a pattern of from stable state to unstable state after dissolving by acid rain.

Seasonal and Spatial Variation of Mo Isotope Compositions in Headwater Stream of Xijiang River Draining the Carbonate Terrain, Southwest China

The dissolved molybdenum (Mo) contents and Mo isotope in water samples from the upper Xijiang River (XJR), draining the carbonate terrain, southwest China, are reported to investigate the seasonal and spatial variations, sources, ion budget, and isotopic fractionation of dissolved Mo. The results show that the Mo concentrations (5.3–18.9 nmol/L) exhibit an extensive variation along the mainstream without significant spatial pattern, but the Mo concentrations are slightly higher in the dry season than in the wet season caused by the dilution effect. There is a slight spatial tendency for δ98/95Mo to become higher along the mainstream (0.51–1.78%), while the seasonal variations in δ98/95Mo values of NPR (Nanpanjiang River) reach and BPR (Beipanjiang River) reach can be identified higher in the dry season but lower in the wet season. Based on the hydro-geochemical analysis, the sources of dissolved Mo are identified as the carbonates and sulfide/sulfate minerals weathering with a seasonal contribution. Moreover, our results suggest there is no significant Mo isotopic fractionation during weathering and riverine transportation. The calculation of Mo budget demonstrates that the dissolved δ98/95Mo of river draining the carbonate terrain is underestimated, which could significantly influence the redox history of oceans by Mo isotope model.

Urinary lead in relation to combustion-derived air pollution in urban environments. A longitudinal study of an international panel

BACKGROUND

Urinary lead (Pb) is generally considered to have limited use in biomonitoring environmental exposure to lead. Carbon load in airway macrophages (AM BC) is an internal marker to assess long-term exposure to combustion-derived aerosol particles. In urban environments, atmospheric Pb and black carbon may have common sources. We aimed to study the temporal change of urinary Pb (U-Pb) when exposure to outdoor air pollution changes, and the relationship between U-Pb and AM BC.

METHODS

A panel of 50 young healthy adults [mean (SD) 26.7 (5.2) years], including 17 long-term (>1 year) residents in Leuven, Belgium (BE), 15 and 18 newcomers (arrived <3 weeks) from low- and middle-income countries (LMIC) and high-income countries (HIC), respectively, underwent 8 repeated measurements at 6 weeks intervals. In urine spot samples obtained at 5 time points (T1, T2, T4, T6, T8), 24 trace elements were quantified by inductively coupled plasma-mass spectrometry. At each time point, AM BC was quantified as the median surface of black inclusions (in μm²) by means of image analysis of 25 macrophages obtained by induced sputum. Changes in urinary metal concentrations (with and without creatinine correction) and the relationship between U-Pb and AM BC were estimated using linear mixed models adjusted for covariates and potential confounders.

RESULTS

Only U-Pb differed between groups and exhibited significant time trends. Participants from the LMIC group had significantly higher initial U-Pb (1.18 μg/g creat) than the HIC group (0.44 μg/g creat) and BE group (0.45 μg/g creat). In the LMIC group, U-Pb decreased significantly with time by 0.061 μg/g creatinine per 30 days [95% confidence interval (CI): 0.034, 0.088]. U-Pb remained unchanged in the other two groups. An increase in AM BC of 1 μm² was associated with an increase in U-Pb of 0.369 μg/g creat (95% CI: 0.145, 0.593).

CONCLUSION

This panel study demonstrates that U-Pb may be a valid alternative to blood Pb for biomonitoring changes in exposure to lead, at least at group level. In addition, we identified a positive association between U-Pb and AM BC, a biomarker of exposure to traffic-related air pollution, suggesting the existence of common sources of Pb and black carbon in urban environments.

Size-fractionated particulate elements in an inland city of China: Deposition flux in human respiratory, health risks, source apportionment, and dry deposition

Size-resolved samples were collected using a 14-stage impactor during four seasons in Zhengzhou and analyzed for 26 elements to calculate the health risks from atmospheric particle-bound metals. High concentrations of heavy metals were observed in ultrafine (10.2 (Ni)-66.9 (Cd) ng m^-3) or submicrometer (11.4 (Ni)-134 (Pb) ng m^-3) mode in winter. Two size-dependent models were used to estimate the deposition of inhaled toxic metals in various regions of the human respiratory system. Results show that heavy metals deposited in the alveolar region ranged from 7.6 (As)-375 (Al) ng m^-3 and were almost concentrated in ultrafine and fine modes. Cd (2.2-8.6) may cause accumulative non-carcinogenic health effects on children, and Cr (1.0 × 10^-4-2.2 × 10^-4) may lead to carcinogenic health risks for nearby residents around the sampling site. The major sources by principal component analysis that contributed to Cr and Cd in ultrafine and fine particles were coal combustion, vehicular and industrial emissions. The atmospheric dry deposition fluxes of Cr and Cd were between 0.7 and 1.9 μg m^-2 day^-1 calculated by a multi-step method. From the environmental and public health perspective, environmental agencies must control the emission of heavy metals in the atmosphere.

Characterization of Human Health Risks from Particulate Air Pollution in Selected European Cities

The objective of the current study was to estimate health risk indexes caused by the inhalation of particulate matter (PM) by adult males and children using data sampled in three European cities (Athens, Kuopio, Lisbon). Accordingly, the cancer risk (CR) and the hazard quotient (HQ) were estimated from particle-bound metal concentrations whilst the epidemiology-based excess risk (ER), the attributable fraction (AF), and the mortality cases were obtained due to exposure to PM10 and PM2.5. CR and HQ were estimated using two methodologies: the first methodology incorporated the particle-bound metal concentrations (As, Cd, Co, Cr, Mn, Ni, Pb) whereas the second methodology used the deposited dose rate of particle-bound metals in the respiratory tract. The indoor concentration accounts for 70% infiltration from outdoor air for the time activity periods allocated to indoor environments. HQ was lower than 1 and the cumulative CR was lower than the acceptable level (10−4), although individual CR for some metals exceeded the acceptable limit (10−6). In a lifetime the estimated number of attributable cancer cases was 74, 0.107, and 217 in Athens, Kuopio, and Lisbon, respectively. Excess risk-based mortality estimates (due to outdoor pollution) for fine particles were 3930, 44.1, and 2820 attributable deaths in Athens, Kuopio, and Lisbon, respectively.

Trace elements in atmospheric wet precipitation in Detroit metropolitan area: Levels and possible sources

Rain and snow samples were collected in the Detroit metropolitan area and analyzed by inductively coupled plasma-mass spectrometry (ICP-MS). Twenty-two elements were detected in a concentration range from ∼0.03 to ∼1.8 × 10³ μg/kg. An enrichment factor (EF), defined as, EF=(X/Al)sample(X/Al)crust , was estimated for each element (X) detected, and used to determine possible origins of the element. Based on the hypothesis that crustal material is the only source of aluminum (Al) found in the atmospheric environment, an EF value near unity for an element suggests that crustal material is a major source of this element. If EF>10, an element is enriched in the atmosphere relative to its concentration in the earth's crust, implying a source other than the crust. Alkali, alkaline earth and lanthanide metals detected in the samples exhibit low EF values, indicating mainly a crustal source. Six elements (As, Cd, Cu, P, Pb and Zn) were significantly enriched in the samples as their EF values were greater than 10, thus originated likely from anthropogenic emissions. The relative order of the significantly enriched elements is estimated as follows: Cd > Pb > Zn > As > Cu > P. A high enrichment (EF∼100) for phosphorus was observed and caused plausibly by extensive usage of phosphorus-containing fertilizers and pesticides.

Metals and metalloids in PM10 in Nandan County, Guangxi, China, and the health risks posed

Intense mining, smelting, and tailing activities of polymetallic ore deposits have affected the environment in Nandan County, Guangxi, China. Samples of particulates with aerodynamic diameters low or equal 10 μm (PM₁₀) were collected in Nandan County to investigate the concentrations of and health risks posed by 17 metals and metalloids in the PM₁₀. The metal and metalloid concentrations were lower than those found in other industrial cities. The mean Cr concentration was 7.48 ng/m³. Significant higher metal and metalloid concentrations were found in PM₁₀ from mining areas (Dachang and Chehe) than from the control area (Liuzhai) (p < 0.05). Principal component analysis indicated that the main sources of Ba, Co, Cr, Fe, K, Mg, Mo, Na, and Sr were resuspension of the soil produced through mineral erosion, the main sources of As, Cd, Cu, Pb, Sb, and Zn were smelting and mining activities, and the main source of Ni was fossil fuel combustion. Higher non-carcinogenic and carcinogenic risks were posed in Dachang and Chehe than in Liuzhai. The non-carcinogenic risks posed to adults and children by individual metals and metalloids in PM₁₀ at all the sites were low, but the non-carcinogenic risks posed to children by all the metals and metalloids together exceeded the safe level (i.e., risk value > 1). The carcinogenic risks posed by Cd, Ni, and Pb were negligible at all sites, while As, Co, and Cr posed potential carcinogenic risks to the residents.

Size distribution and source of heavy metals in particulate matter on the lead and zinc smelting affected area

In order to understand the size distribution and the main kind of heavy metals in particulate matter on the lead and zinc smelting affected area, particulate matter (PM) and the source samples were collected in Zhuzhou, Hunan Province from December 2011 to January 2012 and the results were discussed and interpreted. Atmospheric particles were collected with different sizes by a cascade impactor. The concentrations of heavy metals in atmospheric particles of different sizes, collected from the air and from factories, were measured using an inductively coupled plasma mass spectrometry (ICP-MS). The results indicated that the average concentration of PM, chromium (Cr), arsenic (As), cadmium (Cd) and lead (Pb) in PM was 177.3 ± 33.2 μg/m³, 37.3 ± 8.8 ng/m³, 17.3 ± 8.1 ng/m³, 4.8 ± 3.1 ng/m³ and 141.6 ± 49.1 ng/m³, respectively. The size distribution of PM displayed a bimodal distribution; the maximum PM size distribution was at 1.1-2.1 μm, followed by 9-10 μm. The size distribution of As, Cd and Pb in PM was similar to the distribution of the PM mass, with peaks observed at the range of 1.1-2.1 μm and 9-10 μm ranges while for Cr, only a single-mode at 4.7-5.8 μm was observed. PM (64.7%), As (72.5%), Cd (72.2%) and Pb (75.8%) were associated with the fine mode below 2.1 μm, respectively, while Cr (46.6%) was associated with the coarse mode. The size distribution characteristics, enrichment factor, correlation coefficient values, source information and the analysis of source samples showed that As, Cd and Pb in PM were the typical heavy metal in lead and zinc smelting affected areas, which originated mainly from lead and zinc smelting sources.

Wet and dry deposition fluxes of heavy metals in Pearl River Delta Region (China): Characteristics, ecological risk assessment, and source apportionment

The atmospheric deposition of heavy metals poses serious risks to the ecological system and human health. To advance our knowledge of atmospheric dry/wet heavy metal deposition in the PRD region, monthly fluxes were examined based on soluble/insoluble fractions of five heavy metal elements (Cu, Pb, Cd, Cr and Zn) in samples collected from January 2014 to December 2015 at Guangzhou (urban) and Dinghushan (suburban) sites. The ratios of wet/dry deposition fluxes indicated that heavy metal deposition was governed by wet deposition rather than dry deposition in the PRD region. Affected by the shifting of the Asian monsoon, wet deposition fluxes exhibited significant seasonal variation between summer monsoon seasons (April to September) and winter monsoon seasons (October to February) in this region. Cd was classified as an extremely strong potential ecological risk based on solubility and the Hakanson ecological risk index. Source contributions to wet deposition were calculated by PMF, suggesting that dust, biomass burning, industries, vehicles, long-range transport and marine aerosol sources in Guangzhou, and Zn fertilizers, marine aerosol sources, agriculture, incense burning, biomass burning, vehicles and the ceramics industry in Dinghushan, were the potential sources of heavy metals.

Particle Size Distributions of Oxidative Potential of Lung-Deposited Particles: Assessing Contributions from Quinones and Water-Soluble Metals

Redox-active species in ambient particulate matter (PM) cause adverse health effects through the production of reactive oxygen species (ROS) in the human respiratory tract. However, respiratory deposition of these species and their relative contributions to oxidative potential (OP) have not been described. Size-segregated aerosols were collected during haze and nonhaze periods using a micro-orifice uniform deposit impactor sampler at an urban site in Shanghai to address this issue. Samples were analyzed for redox-active species content and PM OP. The average dithiothreitol (DTT) activity of haze samples was approximately 2.4-fold higher than that of nonhaze samples and significantly correlated with quinone and water-soluble metal concentrations. The size-specific distribution data revealed that both water-soluble OP_v^DTT (volume-normalized OP quantified by DTT assay) and OP_m^DTT (mass-normalized OP) were unimodal, peaking at 0.56-1 and 0.1-0.32 μm, respectively, due to contributions from accumulation-mode quinones and water-soluble metals. We further estimated that transition metals (mainly copper and manganese) contributed 55 ± 13% of the DTT activity while quinones accounted for only 8 ± 3%. Multiple-path particle dosimetry calculations estimated that OP deposition in the pulmonary region was mainly from accumulation-mode transition metals despite quinones having the highest DTT activity. This behavior is primarily attributed to the efficiency of deposition of transition metals in the pulmonary region being approximately 1.2-fold greater than that of quinones. These results reveal that accumulation-mode transition metals are significant contributors to the OP of deposited water-soluble particles in the pulmonary region of the lung.

Physiochemical characteristics of aerosol particles collected from the Jokhang Temple indoors and the implication to human exposure

This paper presents a detailed study on the indoor air pollution in the Jokahng Temple at Tibet Plateau, and its implication to human health. The mean concentrations of PM_1.0 and PM_2.5 were 435.0 ± 309.5 and 483.0 ± 284.9 μg/m³, respectively. The PM_2.5 concentration exceeded the National Ambient Air Quality Standard (75 μg/m³) by 6.4 times. The size-segregated aerosols displayed a bimodal distribution. One peak was observed in the fine mode (0.4-2.1 μm) and the other peak appeared in the coarse mode (2.1-9.0 μm). The concentration of the total size-resolved PM was 794.3 ± 84.9 μg/m³. The mass fraction of coarse particles shared by 41.1%, apparently higher than that reported at low altitudes, probably due to incomplete combustion at Tibet Plateau with hypoxic atmospheric environment. The total concentration of polycyclic aromatic hydrocarbons (PAHs) was 331.2 ± 60.3 ng/m³, in which the concentration of benzo(a)pyrene (BaP) was 18.5 ± 4.3 ng/m³, over ten times higher than the maximum permissible risk value of 1 ng/m³ on account of carcinogenic potency of particulate PAHs through inhalation. PAHs exhibited a trimodal distribution, of which two peaks were observed in the fine mode and one peak in the coarse mode. With the aromatic rings increasing, the peak intensity increased in the fine mode. Na, Ca, Al, Mg and K dominated the elemental mass profiles, and metals displayed a bimodal distribution with a dominant peak in the coarse range. The total PAH deposition flux was 123.6 and 53.1 ng/h for adults and children, respectively. Coarse particles contributed most deposition flux in the head region, while fine particles contribute most deposition flux in the alveolar region. The increment lifetime cancer risk (ILCR) of PAHs ranaged at 10^-5-10^-4, indicating potential cancer risk to human health. The total deposition flux of metals was estimated at 1.4-13.2 ng/h. With the size increasing, deposition flux increased in the head region while decreased in the alveolar region. The highest ILCR of Cr and Ni were 4.9 × 10^-5 and 1.5 × 10^-6, respectively, exceeding the permissible risk of 10^-6. The hazard quotient (HQ) of Fe (10^-5-10^-4) and Zn (10^-6-10^-5) were much lower than the safe level of 1.0, and thus they were not considered as a health concern.