Chronic exposure to environment noise is associated with sleep disturbance and cardiovascular diseases. Assessment of population exposed to environmental noise is limited by a lack of routine noise sampling and is critical for controlling exposure and mitigating adverse health effects. Land use regression (LUR) model is newly applied in estimating environmental exposures to noise. Machine-learning approaches offer opportunities to improve the noise estimations from LUR model. In this study, we employed random forests (RF) model to estimate environmental noise levels in five Canadian cities and compared noise estimations between RF and LUR models. A total of 729 measurements and 33 built environment-related variables were used to estimate spatial variation in environmental noise at the global (multi-city) and local (individual city) scales. Leave one out cross-validation suggested that noise estimates derived from the RF global model explained a greater proportion of variation (R2: RF = 0.58, LUR = 0.47) with lower root mean squared errors (RF = 4.44 dB(A), LUR = 4.99 dB(A)). The cross-validation also indicated the RF models had better general performance than the LUR models at the city scale. By applying the global models to estimate noise levels at the postal code level, we found noise levels were higher in Montreal and Longueuil than in other major Canadian cities.

Urban parks are an important part of the urban ecological environment. The environmental quality of parks is related to human health. To evaluate sources of polycyclic aromatic hydrocarbons (PAHs) in soils of urban parks and their possible health risks, soil samples from 122 parks in Beijing, China, were collected and analyzed. The total content of 16 PAHs between 0.066 and 6.867 mg/kg. Four-ring PAHs were predominant, followed by 5-ring PAHs, while the fraction of 2-ring PAHs was the lowest. The dominant PAHs sources were found to be coal combustion and oil fuels such as gasoline and diesel. A conditional inference tree (CIT) was used to identify the key influencing factors for PAHs. Traffic emissions was the most important factor, followed by coal consumption, as well as the history and location of the park. Incremental lifetime cancer risk (ILCR) for urban park soil in Beijing were low under normal conditions. The soil PAHs exposure pathway risk for both children and adults decreased in the following order: ingestion > dermal contact > inhalation. The risk from soil in parks to children’s health is slightly higher than that of adults, although the health risk due to exposure to PAHs was not extraordinary. Ecosystem risk was negligible.

A pilot study was initiated in 2018 under the Global Atmospheric Passive Sampling (GAPS) Network named GAPS-Megacities. This study included 20 megacities/major cities across the globe with the goal of better understanding and comparing ambient air levels of persistent organic pollutants and other chemicals of emerging concern, to which humans residing in large cities are exposed. The first results from the initial period of sampling are reported for 19 cities for several classes of flame retardants (FRs) including organophosphate esters (OPEs), polybrominated diphenyl ethers (PBDEs), and halogenated flame retardants (HFRs) including new flame retardants (NFRs), tetrabromobisphenol A (TBBPA) and hexabromocyclododecane (HBCDD). The two cities, New York (USA) and London (UK) stood out with ∼3.5 to 30 times higher total FR concentrations as compared to other major cities, with total concentrations of OPEs of 15,100 and 14,100 pg/m³, respectively. Atmospheric concentrations of OPEs significantly dominated the FR profile at all sites, with total concentrations in air that were 2–5 orders of magnitude higher compared to other targeted chemical classes. A moderately strong and significant correlation (r = 0.625, p < 0.001) was observed for Gross Domestic Product index of the cities with total OPEs levels. Although large differences in FR levels were observed between some cities, when averaged across the five United Nations regions, the FR classes were more evenly distributed and varied by less than a factor of five. Results for Toronto, which is a ‘reference city’ for this study, agreed well with a more in-depth investigation of the level of FRs over different seasons and across eight sites representing different urban source sectors (e.g. traffic, industrial, residential and background). Future sampling periods under this project will investigate trace metals and other contaminant classes, linkages to toxicology, non-targeted analysis, and eventually temporal trends. The study provides a unique urban platform for evaluating global exposome.

Trace elements (TEs) in the insoluble particles of surface snow are less affected by melting processes and can be used as environmental proxies to reveal natural and anthropogenic emissions. Here the first comprehensive study of the 16 TEs (Al, As, Ba, Bi, Cr, Cu, Fe, Mn, Ni, Pb, Sn, Sr, Ti, U, V, and Zn) in insoluble particles (>0.45 μm) from surface snow samples collected at Urumqi Glacier No. 1 (UG1), Eastern Tien Shan, China, from February 2008 to January 2010 were presented. Results show that concentrations of most insoluble particulate TEs (TEs ᵢₙₛₒₗ) in the snow were higher in summer while lower in winter, due to the increasing particle inputs and melting processes. The abundances of As, Cr, Cu, Ni, Pb, and Zn in some samples were higher than those in surrounding urban soils, which might due to these TEs have further anthropogenic input beyond the already contaminated re-suspended urban soil particles and TEs were mainly enriched in particles with small grain size. Based on enrichment factor (EF) and principal component analysis (PCA), our results suggest that eight TEs (Al, Fe, Ti, Ba, Mn, Sr, U, and V) mainly came from mineral dust, while the remaining eight TEs (As, Bi, Cr, Cu, Ni, Pb, Sn, and Zn) were affected by coal combustion, mining and smelting of non-ferrous metals, traffic emissions, and the steel industry. The Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model suggests that pollutants might originate from Xinjiang province, Kazakhstan, and Kyrgyzstan. Moreover, UG1 received more significant inputs of particle-bound pollutants in summer than in winter due to the stronger convection and the prevailing valley wind that transports pollutants from the city of Urumqi.

Southwestern China contains the largest and most well-developed karst region in the world, and the potentially toxic elements (PTEs) content in the soils of the region is remarkably high. To explore the internal and external control factors and sources of soil PTEs enrichment in this area and to provide a basis for the treatment of PTE pollution, 113 soil samples were collected from Hengxian County, a karst region in Guangxi Province, southwestern China. The importance of eighteen influencing factors including parent material, weathering, physicochemical properties, topography and human activities were quantitatively analyzed by (partial) redundancy analysis. The sources of PTEs were identified using the Pb isotope ratio and absolute principal component score/multiple linear regression (APCS-MLR) model. The contents of all soil PTEs were higher than the corresponding background values of Guangxi soils. The contents in Cu, Zn, Cd, Hg and Pb were the highest in the soil from carbonate rock. The factor group of geological background and weathering explained 26.5% for the accumulation and distribution of soil PTEs and the influence of physicochemical properties was less than 2% but increased to 25.6% through interaction with weathering. Fe (47.1%), Al (42.1%), Mn (22%), chemical index of alteration (12.8%) and clay (11.9%) were the key factors affecting the soil PTEs, while the influence of human activities was weak. Pb isotope ratio and APCS-MLR classified 62.8–74% of soil PTEs as derived from natural sources, whereas 18.23% and 18.95% were derived from industrial activities and agricultural practice/traffic emissions, respectively. The Pb isotope ratio showed that the natural sources account for up to 90% of the Pb in the soil from carbonate rock, the highest contribution among the studied soils. The results of the study can provide background information on the soil PTEs contamination in the karst areas of China and other areas worldwide.

Increasing levels of road noise are creating new anthropogenic soundscapes that may affect wildlife globally. Bats, which form about a third of all mammal species, are sensitive bioindicators, and may be particularly vulnerable because of their dependency on echolocation. Here we present the first controlled field experiment with free-living bats. Using a Before-After-Control-Impact phantom road experimental design, we examine the impacts of traffic noise on their activity and feeding behaviour. Disentangling the impacts of traffic noise from other co-varying exposures such as habitat quality, the experiment demonstrates a significant negative effect on the activity of each of the five, ecologically different, species (genus for Myotis spp.) examined. This suggests that the results are widely applicable. The negative effects are largely attributable to noise in the sonic spectrum, which elicited aversive responses in all bat species tested,whereas responses to ultrasoundwere restricted to a single species. Our findings demonstrate that traffic noise can affect bat activity at least 20m away from the noise source. For Pipistrellus pipistrellus and Pipistrellus pygmaeus, feeding behaviour, as well as overall activity, was negatively affected. Ecological Impact Assessments are therfore needed wherever there are significant increases in traffic flow, and not just when new roads are built. Further research is required to identify effective mitigation strategies, to delineate the zone of influence of road noise, and to assess whether there is any habituation over time.

Light absorbing carbonaceous aerosols (LACA) consisting of black carbon (BC) and brown carbon (BrC) have received considerable attention because of their climate and health implications, but their sources, characteristics and fates remain unclear in Southeast Asia (SEA). In this study, we investigated spatio-temporal characteristics of LACA, their radiative properties and potential sources in Singapore under different weather conditions. Hourly BC concentrations, measured from May 2017 to March 2018, ranged from 0.31 μg/m³ to 14.37 μg/m³ with the mean value being 2.44 ± 1.51 μg/m³. High mass concentrations of BC were observed during the south-west monsoon (SWM, 2.60 ± 1.56 μg/m³) while relatively low mass concentrations were recorded during the north-east monsoon (NEM, 1.68 ± 0.96 μg/m³). There was a shift in the Absorption Ångström exponent (AAE) from 1.1 to 1.4 when the origin of LACA changed from fossil fuel (FF) to biomass burning (BB) combustion. This shift is attributed to the presence of secondary BrC in LACA, derived from transboundary BB emissions during the SWM. Lower AAE values were observed when local traffic emissions were dominant during the NEM. This explanation is supported by measurements of water-soluble organic carbon (WSOC) in LACA and the corresponding AAE values determined at 365 nm using a UV–vis spectrophotometer. The AAE values, indicative of the presence of brown carbon (BrC), showed that photochemically aged LACA contribute to an enhancement in the light absorption of aerosols. In addition, spatio-temporal characteristics of BC in the intra-urban environment of Singapore were investigated across diverse outdoor and indoor microenvironments. High variability of BC was evident across these microenvironments. Several air pollution hotspots with elevated BC concentrations were identified. Overall, the results stress a need to control anthropogenic emissions of BC and BrC in order to mitigate near-term climate change impacts and provide health benefits.

This study assessed the sources, magnitudes, and chemical compositions of household air pollution (HAP) and personal exposure in traditional Tibetan households. We measured 24-h personal exposures to PM₂.₅ and kitchen area black carbon (BC) concentrations, using MicroPEMs and microAeths, respectively. Particulate polycyclic aromatic hydrocarbon (PAH) and inorganic element concentrations were quantified via post analyses of a subset of MicroPEM sample filters. Household surveys regarding participant demographics, cookstove usage, household fuel, cooking behaviors, and lifestyles were collected. The results reaffirm that burning firewood and yak dung, mainly for cooking, leads to high PM₂.₅ and BC exposures. The geometric mean concentration (95% confidence interval, CI) was 74.3 (53.6, 103) μg/m³ for PM₂.₅ and the arithmetic mean ± standard deviation (SD) concentration was 4.90 ± 5.01 μg/m³ for BC and 292 ± 364 ng/m³ for 15 identified PAHs, respectively. The arithmetic mean ± SD of mass concentrations of 24 detected elements ranged from 0.76 ± 0.91 ng/m³ (Co) to 1.31 ± 1.35 μg/m³ (Si). Our statistical analyses further illustrated that the high concentrations of PM₂.₅, BC, and most PAHs and metals, are significantly associated with nomadic village, poorer stove/chimney conditions and yak dung burning. The results from this study show that substantial HAP exposure is prevalent in Tibetan households and requires immediate actions to mitigate potential negative environmental health impacts. The observational data also revealed the possibility of other important sources (e.g. traffic and garbage burning) that have contributed to personal exposures. These findings improve our understanding of HAP exposure and potential health risks in Tibetan communities and will help inform strategies for reducing HAP in Tibetan households and beyond.

Adverse health effects of exposure to air pollution have been investigated in many previous studies. However, there is no study available on the association between maternal exposure to air pollution during pregnancy and cord blood lipid profile. This study, based on 150 mother-newborn pairs residing in Sabzevar, Iran (2018), evaluated the association of exposure to ambient air pollution as well as traffic indicators (total street length in different buffers around residential address and distance to major roads) during entire pregnancy with lipid levels cord blood lipid profile. Concentrations of PM₁₀, PM₂.₅, and PM₁ at maternal residential address were estimated using land use regression (LUR) models. We measured triglyceride (TAG), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), total cholesterol (TC) levels and TC/HDL-C and TAG/HDL-C ratio in the cord blood samples to characterize their lipid profile. Multiple linear regression models were developed to estimate the association of exposure to air pollution and traffic indicators with cord blood lipid profile controlled for relevant covariates. Higher concentrations of PM₂.₅ and PM₁₀ were associated with higher levels of TAG, TC, HDL-C, TC/HDL-C, and TAG/HDL-C in cord blood samples. Moreover, higher concentration of PM₁ was associated with higher levels of TAG, TC and LDL-C. There was also a positive association between total street length in 100 m buffer around home and serum levels of TC, TAG, LDL-C and TC/HDL ratio (β = 3.73, 95% confidence intervals (CI): 1.76, 5.71; β = 2.75, 95% CI: 0.97, 4.53; β = 1.87, 95% CI: 0.64, 3.09; β = 0.06, 95% CI: 0.01, 0.11, respectively). However, the associations for total street length in larger buffers and distance to major roads were not statistically significant. Our findings support a relationship between exposure to air pollution during pregnancy and increase in cord blood lipid levels.

Particulate air pollution in cities comprises a variety of harmful compounds, including fine iron rich particles, which can persist in the air for long time, increasing the adverse exposure of humans and living things to them. We studied street tree (among other species, Cordyline australis, Fraxinus excelsior and F. pensylvanica) barks as biological collectors of these ubiquitous airborne particles in cities. Properties were determined by the environmental magnetism method, inductively coupled plasma optical emission spectrometry and scanning electron microscopy, and analyzed by geostatistical methods. Trapped particles are characterized as low-coercivity (mean ± s.d. value of remanent coercivity Hcᵣ = 37.0 ± 2.4 mT) magnetite-like minerals produced by a common pollution source identified as traffic derived emissions. Most of these Fe rich particles are inhalable (PM₂.₅), as determined by the anhysteretic ratio χARM/χ (0.1–1 μm) and scanning electron microscopy (<1 μm), and host a variety of potentially toxic elements (Cr, Mo, Ni, and V). Contents of magnetic particles vary in the study area as observed by magnetic proxies for pollution, such as mass specific magnetic susceptibility χ (18.4–218 × 10⁻⁸ m³ kg⁻¹) and in situ magnetic susceptibility κᵢₛ (0.2–20.2 × 10⁻⁵ SI). The last parameter allows us doing in situ magnetic biomonitoring, being convenient because of species preservation, measurement time, and fast data processing for producing prediction maps of magnetic particle pollution.