Bacteria are important components of bioaerosols with the potential to influence human health and atmospheric dynamics. However, information on the concentrations and influencing factors of viable bacteria is poorly understood. In this study, size-segregated bioaerosol samples were collected from Aug. 2017 to Feb. 2018 in the coastal region of Qingdao, China. The total microbes and viable/non-viable bacteria in the samples were measured using an epifluorescence microscope after staining with the DAPI (4′, 6-diamidino-2-phenylindole) and LIVE/DEAD® BacLight™ Bacterial Viability Kit, respectively. The concentrations of non-viable bacteria increased when the air quality index (AQI) increased from <50 to 300, with the proportion of non-viable bacteria to total microbes increasing from (11.1 ± 12.0)% at an AQI of <50 to (18.4 ± 14.7)% at an AQI of >201. However, the concentrations of viable bacteria decreased from (2.12 ± 2.04) × 10⁴ cells·m⁻³ to (9.00 ± 1.72) × 10³ cells·m⁻³ when the AQI increased from <50 to 150. The ratio of viable bacteria to total bacteria (viability) decreased from (31.0 ± 14.7)% at 0 < AQI<50 to (8.6 ± 1.0)% at 101 < AQI<150 and then increased to (9.6 ± 5.3)% at an AQI of 201–300. The results indicated that the bacterial viability decreased when air pollution occurred and increased again when pollution became severe. The mean size distribution of non-viable bacteria exhibited a bimodal distribution pattern at an AQI<50 with two peaks at 2.1–3.3 μm and >7.0 μm, while the viable bacteria had two peaks at 1.1–2.1 μm and >7 μm. When the AQI increased from 101 to 300, the size distribution of viable/non-viable bacteria varied with an increased proportion of fine particles. The multiple linear regression analysis results verified that the AQI and PM₁₀ had important effects on the concentrations of non-viable bacteria. These results highlight impacts of air pollution on viable/non-viable bacteria and the interactions between complex environmental factors and bacteria interactions, improving our understanding of bioaerosols under air pollution conditions.

Urbanization is conducive to promoting social development and improving living standards. However, the changing land use attributed to urbanization has placed both the environment and humans at risk. Based on the long-term monitoring and the land use change during 2010–2017, we investigated the exposure of fluoride (F) and arsenic (As) in groundwater. We analyzed the temporal and spatial variation of F and As from different land use changes. The study assessed health risk for children by calculating carcinogenic risk and non-carcinogenic risk. Furthermore, we mapped the distribution pattern of F and As using GIS. For the 768 water samples collected from 2010 to 2017, F concentrations ranged between 0.10 and 5.70 mg L⁻¹ (M = 0.68 ± 0.02 mg L⁻¹), As concentrations ranged between 0.50 and 71.50 μg L⁻¹ (M = 4.28 ± 0.28 μg L⁻¹). A concerning result showed that 6.77% of F concentrations larger than 1.5 mg L⁻¹ and 11.46% of As concentrations larger than 10 μg L⁻¹ based on the recommendation by WHO, respectively. Results proved that land use change caused by human activity increased groundwater pollution and placed human health at risk. High F and As risk were found in southern Taiyuan City. In particular, the groundwater of industrial land suffered from more severe pollution, especially at the frontier of urban and suburban areas in the southern part of Taiyuan City. Land use change attributed to industrial land resulted in major increases in the F and As concentrations in groundwater across 2010–2017. Both carcinogenic risk and non-carcinogenic risk in 2016–2017 were higher than that in 2010–2015. Rational land use planning, strict groundwater protection policies and the regular monitoring of pollution levels are necessary in order to prevent the adverse health of residents.

Disinfection means the killing of pathogenic organisms (e.g. bacteria and its spores, viruses, protozoa and their cysts, worms, and larvae) present in water to make it potable for other domestic works. The substances used in the disinfection of water are known as disinfectants. At municipal level, chlorine (Cl₂), chloramines (NH₂Cl, NHCl₂), chlorine dioxide (ClO₂), ozone (O₃) and ultraviolet (UV) radiations, are the most commonly used disinfectants. Chlorination, because of its removal efficiency and cost effectiveness, has been widely used as method of disinfection of water. But, disinfection process may add several kinds of disinfection by-products (DBPs) (∼600–700 in numbers) in the treated water such as Trihalomethanes (THM), Haloacetic acids (HAA) etc. which are detrimental to the human beings in terms of cytotoxicity, mutagenicity, teratogenicity and carcinogenicity. In water, THMs and HAAs were observed in the range from 0.138 to 458 μg/L and 0.16–136 μg/L, respectively. Thus, several regulations have been specified by world authorities like WHO, USEPA and Bureau of Indian Standard to protect human health. Some techniques have also been developed to remove the DBPs as well as their precursors from the water. The popular techniques of DBPs removals are adsorption, advance oxidation process, coagulation, membrane based filtration, combined approaches etc. The efficiency of adsorption technique was found up to 90% for DBP removal from the water.

Windowsill, heavy metal-containing dust samples, collected at different building heights, may provide some insight into both source and human health risk. Windowsill dust samples were collected from the 1st to 9th floor (1.4–23.2 m above ground) near a lead smelter (1 km to the smelter) and in urban areas (4.2–7.3 km to the smelter) and separated into <10, 10–45 and 45–125 μm size fractions. Samples were extracted with artificial lysosomal fluid (ALF) and the physiologically based extraction test (PBET) (<10 μm fractions only), subjected to scanning electron microscopy-energy dispersive x-ray spectroscopy (SEM-EDS) and Pb isotopic analysis. Greater Pb concentrations were found in 10–45 μm fraction than the other size fractions; at the PX site, dust Pb concentrations increased with windowsill height, while an opposite trend was found at other sites. Isotopic analysis and SEM-EDS results supported this contention. Higher floor samples collected near the smelter were more affected by lead smelting than lower floor samples; lower floor samples collected at urban sites were more affected by resuspended Pb-laden particles from the ground than higher floors. The Pb bioaccessible fraction (BAF) in the ALF and PBET ranged between 68.9-90.1 and 1.3–17.0%, respectively; urban samples had greater BAF values than samples collected near the smelter. This, first of its kind investigation regarding Pb in dusts at different building heights, provides further insight for reducing human health risks within Pb smelter vicinities.

Gestational diabetes mellitus (GDM) is associated with adverse short- and long-term health outcomes among mothers and their offspring. GDM affects 0.6%–15% of pregnancies worldwide and its incidence is increasing. However, intervention strategies are lacking for GDM. Previous studies indicated a protective association between greenspace and type 2 diabetes mellitus (T2DM), while few studies have explored the association between greenness and GDM. This study aimed to investigate the association between residential greenness and GDM among women from 40 clinical centers in Guangdong province, south China. The study population comprised 5237 pregnant mothers of fetuses and infants without birth defects, from 2004 to 2016. There were n = 157 diagnosed with GDM according to World Health Organization criteria. We estimated residential greenness using the Normalized Difference Vegetation Index (NDVI), derived from satellite imagery using a spatial-statistical model. Associations between greenness during pregnancy and GDM were assessed by confounder-adjusted random effects log-binomial regression models, with participating centers as the random effect. One interquartile increments of NDVI₂₅₀ₘ, NDVI₅₀₀ₘ and NDVI₁₀₀₀ₘ were associated with 13% (RR = 0.87, 95%CI: 0.87–0.87), 8% (RR = 0.92, 95%CI: 0.91–0.92) and 3% (RR = 0.97, 95%CI: 0.97–0.97) lower risks for GDM, respectively. However, NDVI₃₀₀₀ₘ was not significantly associated with GDM (RR = 0.96, 95%CI: 0.78–1.19). The risk for GDM decreased monotonically with greater NDVI. The protective effect of greenness on GDM was stronger among women with lower socioeconomic status and in environments with a lower level air pollutants. Our results suggest that greenness might provide an effective intervention to decrease GDM. Greenness and residential proximity to greenspace should be considered in community planning to improve maternal health outcomes.

The widespread production and use of silver nanomaterials (AgNMs) in consumer and medical products have been raising environmental concerns. Once in the environment, the soil is one of the major sinks of AgNMs due to e.g. sewage sludge applications, and invertebrates are directly exposed. In this study, we investigate the potential of N-acetylcysteine (NAC) to reduce the toxic effects of Ag NM300 K (and AgNO3) on the soil invertebrate Enchytraeus crypticus. Ag NM300 K induces mortality, reproduction impairment, and avoidance. The addition of NAC to the soil showed a remarkable reduction in the toxicity of Ag, indicating that NAC can act as a detoxifying agent for terrestrial organisms exposed to Ag materials. That the reduction in toxicity likely is caused by thiol groups, was confirmed by GSH and GSSH studies. Identifying the mechanisms and hence alternatives that allow the recovery of contaminated soils is an important mitigation measure to promote environmental safety and reduce the associated risks to human health. Further, it may inform on strategies to implement in safe-by-design industry development.

Wastewater reuse in food crop irrigation has led to agroecosystem pollution concerns and human health risks. However, there is limited attention on the relationship of sub-lethal antibiotic levels in vegetables and resistance selection. Most risk assessment studies show non-significant toxicity, but overlook the link between antibiotics in crops and propagation of gut microbiome resistance selection. The review highlights the risk of antibiotics in treated water used for irrigation, uptake, and accumulation in edible vegetable parts. Moreover, it elucidates the risks to the adaptive resistance selection of the gut microbiome from sub-lethal antibiotic levels, as a result of dietary contaminated vegetables. Experiments have reported that bacterial resistance selection is possible at concentrations that are several hundred-folds lower than lethal effect levels on susceptible cells. Consequently, mutants selected at low antibiotic levels, such as those from vegetables, are fitter and more resistant compared to those selected at high concentrations. Necessary standardization, such as the development of minimum acceptable antibiotic limits allowable in food crop irrigation water, with a focus on minimum selection concentration, and not only toxicity, has been proposed. Wastewater irrigation offers environmental benefits and can contribute to food security, but it has non-addressed risks. Research gaps, future perspectives, and frameworks of mitigating the potential risks are discussed.

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.

Scots pine (Pinus sylvestris L.) is a widespread tolerant forest tree-species; however, its adaptability to environmental change differs among sites with various buffering capacity. In this study, we compared the spatial effects of aridity index (AI) and nitrogen deposition (ND) on biomass density in natural and man-made pine stands of differing soil fertility using geographically weighted multiple lag regression. Soil fertility was defined using soil series as zonal trophic (27.9%), acidic (48.2%), gleyed (15.2%) and as azonal exposed (2.5%), maple (2.4%), ash (0.8%), wet (2.1%) and peat (0.9%) under pine stands in the Czech Republic (Central Europe; 4290.5 km²; 130–1298 m a.s.l.). Annual AI and ND in every pine stand were estimated by intersection between raster and vector from 1 × 1 km grid for years 2000, 2003, 2007 and 2010 of severe non-specific forest damage spread. Biomass density was obtained from a MODIS 250 × 250 m raster using the enhanced vegetation index (EVI) for years 2000–2015, with a decrease in EVI indicating non-specific damage. Environmental change was assessed by comparing predictor values at EVI time t and t+λ. Non-specific damage was registered over 51.9% of total forest area. Less than 8.8% of damaged stands were natural and the rest (91.2%) of damaged stands were man-made. Pure pine stands were more damaged than mixed. The ND effect prevailed up to 2007, while AI dominated later. Temporal increasing ND effect under AI effectiveness led to the most significant pine stand damage in 2008 and 2014. Predictors from 2000 to 2007 afflicted 58.5% of non-specifically damaged stands at R² 0.09–0.76 (median 0.38), but from 2000 to 2010 afflicted 57.1% of the stands at R² 0.16–0.75 (median 0.40). The most damaged stands occurred on acidic sites. Mixed forest and sustainable management on natural sites seem as effective remediation reducing damage by ND.

Microfibers are reported as the most abundant microparticle type in the environment. Their small size and light weight allow easy and fast distribution, but also make it challenging to determine their chemical composition. Vibrational microspectroscopy methods as infrared and spontaneous Raman microscopy have been widely used for the identification of environmental microparticles. However, only few studies report on the identification of microfibers, mainly due to difficulties caused by their small diameter. Here we present the use of Stimulated Raman Scattering (SRS) microscopy for fast and reliable classification of microfibers from environmental samples. SRS microscopy features high sensitivity and has the potential to be faster than other vibrational microspectroscopy methods. As a proof of principle, we analyzed fibers extracted from the fish gastrointestinal (GIT) tract, deep-sea and coastal sediments, surface seawater and drinking water. Challenges were faced while measuring fibers from the fish GIT, due to the acidic degradation they undergo. However, the main vibrational peaks were still recognizable and sufficient to determine the natural or synthetic origin of the fibers. Notably, our results are in accordance to other recent studies showing that the majority of the analyzed environmental fibers has a natural origin. Our findings suggest that advanced spectroscopic methods must be used for estimation of the plastic fibers concentration in the environment.