Smelting activities are considered as the primary cause of heavy metal (HM) accumulation in soils, and the human health around the smelter has been a great concern worldwide. In this study, a total of 242 agricultural soil samples were collected around a large scale Pb/Zn smelter in China, and eight HMs (As, Cd, Cr, Cu, Hg, Ni, Pb and Zn) were analyzed to assess HMs status, ecological -health risks, and identify source. Monte Carlo simulation was utilized to evaluate the probabilistic health risks, and positive matrix factorization (PMF) was employed to identify sources. The results revealed the average contents of five heavy metals (Cd 5.28 mg/kg, Pb 203.36 mg/kg, Hg 0.39 mg/kg, Zn 293.45 mg/kg, Cu 37.14 mg/kg) are higher than their background values in Hunan province. Cd had the highest mean pollution index (PI) of 41.8 and the greatest average ecological risk index (Eᵣ) of 1256.34, indicating that Cd was the primary enriched pollutant and had a higher ecological risk than other HMs. The mean hazard index (HI) through exposure to eight HMs was 2.95E-01 and 9.74E-01 for adults and children, respectively, with 35.94% of HI values for children exceeding the risk threshold of 1. Moreover, the mean total cancer risks (TCR) were 2.75E-05 and 2.37E-04 for adults and children, respectively, with 75.48% of TCR values for children exceeding the guideline value of 1E-04. In addition, the positive matrix factorization results showed smelting activities, natural sources, agricultural activities and atmospheric deposition were the three sources in soils, with the contribution rate of 48.62%, 22.35%, and 29.03%, respectively. The uncertainty analysis of the PMF indicated that the three-factor solution is reliable. This work will provide scientific reference for the comprehensive prevention of soil HM pollution adjacent to the large smelter.

Indoor air quality ((IAQ) in classrooms was associated with the daily exposure of school-age children who are particularly vulnerable to air pollutants exposure, while few data exist to evaluate classroom indoor air quality nationwide in China. The subsample of the CIEHS 2018 study was performed in 66 classrooms of 22 primary schools nationwide in China. Temperature, relative humidity, PM₂.₅, PM₁₀, CO₂, CO, formaldehyde concentrations, bacteria and fungi were detected in all classrooms by using the instruments that meet the specified accuracy. The ratios of indoor to outdoor (I/O) of PM₂.₅ were calculated in each classroom to identify whether the indoor environment the pollutants comes from outdoors. The indoor PM₂.₅, PM₁₀, CO, HCHO, bacteria and fungi GM concentration are 47.40 μg/m³, 72.91 μg/m³, 0.37 mg/m³, 0.02 mg/m³, 347.51 CFU/m³ and 362.76 CFU/m³, respectively. We observed that there were 66.5%, 52.6%, 22.4%, 1.8%, and 9.6% of the classrooms that exceeded the guideline values of PM₂.₅, PM₁₀, CO₂, HCHO, and bacteria, respectively. It should be attention that all of the classroom's PM₂.₅ concentrations in Shijiazhuang and Nanning, PM₁₀ concentrations in Nanning, CO₂ concentration in Lanzhou were exceeded the suggested values. Bacteria contamination in Shijiazhuang's classrooms is also serious. All classroom CO concentrations meet the requirement. The results indicated that classroom indoor PM₂.₅ was significantly positively correlated with indoor PM₁₀ and CO₂, while was negative correlated with temperature, CO, and fungi. Our results suggest that indoor air pollution in classrooms was a severe problem in Chinese primary schools. It is necessary to strengthen ventilation in the classroom to improve indoor air quality. What's more, a healthy learning environment should be created for primary school students.

The impacts of COVID-19 lockdown restrictions have provided a valuable global experiment into the extent of improvements in air quality possible with reductions in vehicle movements. Mexico City, London and Delhi all share the problem of air quality failing WHO guideline limits, each with unique situations and influencing factors. We determine, discuss and compare the air quality changes across these cities during the COVID-19, to understand how the findings may support future improvements in their air quality and associated health of citizens. We analysed ground-level PM₁₀, PM₂.₅, NO₂, O₃ and CO changes in each city for the period 1st January to August 31, 2020 under different phases of lockdown, with respect to daily average concentrations over the same period for 2017 to 2019. We found major reductions in PM₁₀, PM₂.₅, NO₂ and CO across the three cities for the lockdown phases and increases in O₃ in London and Mexico City but not Delhi. The differences were due to the O₃ production criteria across the cities, for Delhi production depends on the VOC-limited photochemical regime. Levels of reductions were commensurate with the degree of lockdown. In Mexico City, the greatest reduction in measured concentration was in CO in the initial lockdown phase (40%), in London the greatest decrease was for NO₂ in the later part of the lockdown (49%), and in Delhi the greatest decrease was in PM₁₀, and PM₂.₅ in the initial lockdown phase (61% and 50%, respectively). Reduction in pollutant concentrations agreed with reductions in vehicle movements. In the initial lockdown phase vehicle movements reduced by up to 59% in Mexico City and 63% in London. The cities demonstrated a range of air quality changes in their differing geographical areas and land use types. Local meteorology and pollution events, such as forest fires, also impacted the results.

Polycyclic aromatic compounds (PACs) in Canadian air and deposition were examined at the national scale for the first time in over twenty-five years. Air concentrations spanned four orders of magnitude, and were highest near industrial emitters and lowest in the Arctic. Declines in unsubstituted PAHs were observed at locations close to industrial facilities that had reduced emissions, but trends elsewhere were modest or negligible. Retene concentrations are increasing at several locations. Ambient concentrations of benzo[a]pyrene exceeded Ontario’s health-based guideline in many urban/industrial areas. The estimated toxicity of the ambient PAC mixture increased by up to a factor of six when including compounds beyond the US EPA PAHs. Knowledge of PAC deposition is limited to the Laurentian Great Lakes and Athabasca Oil Sands regions. The atmosphere remained a net source of PAHs to the Great Lakes, though atmospheric inputs were decreasing with halving times of 26–30 years. Chemical transport modelling substantially overestimated wet deposition, but model performance is unknown for dry deposition. Sources from Asia, Europe and North America contributed to Arctic and Sub-Arctic concentrations, whereas transboundary or long-range transport have not been assessed outside Canada’s north. Climate-related impacts from re-emission and forest fires were implicated in maintaining air concentrations in the high Arctic that were not consistent with global emissions reductions. Industrial emission decreases were substantial at the national scale, but their influence on the environment was limited to areas near relevant facilities. When examined through the lens of ambient levels at the local scale, evidence suggested that contributions from residential wood combustion and motor vehicles were smaller and larger, respectively, than those reported in national inventories. Future work aimed at characterizing PACs beyond the EPA PAHs, improving measurement coverage, elucidating deposition phenomena, and refining estimates of source contributions would assist in reducing remaining knowledge gaps about PACs in Canada.

Vehicular emissions are known to be major contributors of airborne polycyclic aromatic hydrocarbons (PAHs) in cities. In order to assess the long-term contamination of PAHs along roads, we collected organic films from vehicle windows (26 private cars and 4 buses, in Shanghai, China) and used mathematical models to convert the film-bound PAH concentrations to the airborne PAH concentrations. The field measurements of airborne PAHs revealed that the partitioning and Level III fugacity model was suitable to estimate the airborne concentrations of high and low volatile PAHs (expect for naphthalene), respectively. The total airborne PAH concentrations along roads in Shanghai ranged from 0.83 to 3.37 μg m⁻³ and the incremental lifetime cancer risks (ILCRₜₒₜₐₗ) by exposure to PAHs along roads were greater than the USEPA lower guideline of 10⁻⁶, indicating non-negligible carcinogenic risks to drivers and passengers, especially via ingestion processes. This study provided a practicable method to investigate long-term air contamination of PAHs in vehicles and along roads based on film-bound PAH on vehicle windows. In addition, it was also possible to investigate the health risk in vehicles as a result of exposure to PAHs. Comparisons of PAHs between roads and shipping lanes also facilitated the delineation of vehicular and shipping PAH inventories.A capsule that summarizes the main finding of the work: Investigating film-bound PAH on vehicle windows is a practicable pathway to investigate the long-term contamination of PAHs in vehicles and along roads. This method can not only simplify the sampling processes, but the model calculations. The results also enabled investigations into ILCR in vehicles and specified source apportionment of traffic PAHs.

To better understand the real-world emissions of rural vehicles (RVs) in China, 8 China II RVs and 18 China III RVs were tested on a provincial road, rural road and farm road using a portable emissions measurement system. The results are illustrated in contour maps of the speed, acceleration and emission rates and show that CO, HC, NOx and PM emissions differ for the three road types; however, the peak emission points all occur on the provincial road. The average CO, HC, NOx and PM emission factors based on distance for the China II RVs are 9.21, 4.05, 1.68 and 2.58 times higher, respectively, than those of the China III RVs. However, the average NOx emission factors of the China II and III RVs are 2.21 and 1.65 times higher than the corresponding recommended values of national emission inventory guideline, resulting in underestimation of overall RVs’ emissions. Distance-based emission factors of four pollutants ranked from high to low are farm road > rural road > provincial road. In contrast to the average emission factors of the China II RVs on the three road types, those of the China III RVs are significantly less in terms of distance and fuel consumption. The results of other researchers differ from those in this study: the CO emission factor of the China II RVs is 2.12 times higher than that of the China II light-duty diesel vehicles (LDDVs). The PM emission factor of the China III RVs is 2.67 times higher than that of the China III LDDVs. The NOx emission factors of the China II and III RVs are similar to those of the corresponding China II and III LDDVs. Our research increases the understanding of real-world emissions of RVs and can act as great references for policy makers developing RV emission baselines.

Mining activities in the world's largest platinum mining area in South Africa have resulted in environmental contamination with Pt (e.g., the Hex River's vicinity). The present study compared a Pt mining area with a non-mining area along this river in terms of (1) metal concentrations in different grain size fractions from soils and aquatic sediments; (2) the toxicological potential of aquatic sediments based on the Consensus-Based Sediment Quality Guideline (CBSQG); and (3) the chronic toxicity of aqueous eluates from soils and sediments to Caenorhabditis elegans. Platinum concentrations were higher in the mining area than in the non-mining area. For most metals, the sediment silt and clay fraction contained the highest metal concentrations. Based on the CBSQG, most sampling sites exhibited a high toxicological potential, driven by Cr and Ni. Eluate toxicity testing revealed that C. elegans growth, fertility, and reproduction inhibition were not dependent on mining activities or the CBSQG predictions. Toxicity was instead likely due to Cd, Fe, Mn, Ni, Pt, and Pb. In conclusion, the investigated region is loaded with a high geogenic background resulting in high reproduction inhibition. The mining activities lead to additional environmental metal contamination (particularly Pt), contributing to environmental soil and sediment toxicity.

Communities in low-income and middle-income countries (LMIC) are disproportionally affected by industrial pollution compared to more developed nations. This study evaluates the dispersal and associated health risk of contaminant-laden soil and dust at a copper (Cu) smelter in Tsumeb, Namibia. It is Africa’s only smelter capable of treating complex Cu ores that contain high arsenic (As) contents (<1%). The analyses focused on the primary trace elements associated with ore processing at the smelter: As, Cu, and lead (Pb). Portable X-Ray fluorescence spectrometry (pXRF) of trace elements in soils (n = 83) and surface dust wipes (n = 80) showed that elemental contamination was spatially associated with proximity to smelter operations. Soil concentrations were below US EPA soil guidelines. Dust wipe values were elevated relative to sites distal from the facility and similar to those at other international smelter locations (As = 1012 μg/m² (95% CI 687–1337); Cu = 1838 μg/m² (95% CI 1191–2485); Pb = 1624 μg/m² (95% CI 862–2385)). Source apportionment for Pb contamination was assessed using Pb isotopic compositions (PbIC) of dust wipes (n = 22). These data revealed that the PbIC of 73% (n = 16/22) of these wipes corresponded to the PbIC of smelter slag and tailings, indicating contribution from industrial emissions to ongoing exposure risk. Modeling of carcinogenic risk showed that dust ingestion was the most important pathway, followed by inhalation, for both adults and children. Dermal contact to trace elements in dust was also determined to pose a carcinogenic risk for children, but not adults. Consequently, contemporary smelter operations remain an ongoing health risk to the surrounding community, in spite of recent efforts to improve emissions from the operations.

Urbanization and industrialization have elevated metal concentrations in soils. However, systematic investigation on their availability in regional soils under industrial impacts is lacking. In this study, 230 paired soil-rice samples were collected from two areas in Southeast China, with low and high industrial impacts. Classic equilibrium-based CaCl₂ and EDTA extraction methods, and dynamic-based diffusive gradients in thin-films (DGT) technique were used to study metal availability in soils, with the results being compared with metal concentrations in soils and rice grains. Generally, Cd, Ni, Cu, Zn, Cr and Pb concentrations in soils exceeded the Chinese Soil Quality Standard (GB15618-2018), whereas only Cd and Ni in some rice grains exceeded the Chinese Safety Guidelines. CaCl₂ and EDTA extractions, DGT method and soil total metal concentrations provided good predication of grain Cd (R = 0.51–0.66, p < 0.01), whereas only CaCl₂ and DGT tests provided good predication of grain Ni (R = 0.36–0.47, p < 0.01). Overall, CaCl₂ extraction best predicted Cd and Ni accumulation in rice grains, explaining 66% of grain Cd and 47% of grain Ni. The extraction rate of available Cd was higher than that of Ni, indicating higher Cd availability than Ni, consistent with the parameters (response time, Tc, and desorption rate, k–₁) from DIFS (DGT-induced flux in soils) model and bioconcentration factor values. This study showed that, at regional scale, CaCl₂ extraction method is efficient in predicting Cd and Ni accumulation in rice grains from contaminated soils.

Cadmium (Cd) is a heavy metal of concern in contaminated sites because of its high toxicity to soil biota and humans. Typically, Cd exposure is thought to be dominated by dissolved Cd in soil pore water and, thus, dermal uptake. In this study, we investigated the uptake, toxicity, and maternal transfer of Cd in a standard soil invertebrate, the oribatid mite (Oppia nitens), which is common to boreal and temperate ecozones. We found total soil Cd predicted Cd uptake in adult and juvenile O. nitens with no significant uptake from pore water by juvenile mites. Cadmium significantly inhibited juvenile production and recruitment as well as reduced adult fecundity. Adult O. nitens maternally transferred 39–52% of their Cd body burden to juveniles (tritonymphs) while the maternally-acquired Cd accounted for 41% of the juvenile internal Cd load. Our results suggest that dermal adsorption of metal ions is not important for O. nitens and that maternal transfer of Cd in soil invertebrates has ecological and toxicological implications for populations of soil invertebrates. Maternal transfer should be incorporated as a criterion in setting environmental soil quality guidelines (SQGE) for cadmium and other non-essential heavy metals.