The purpose of this study is to investigate the potential associations between air pollution and dry eye disease (DED). Data of outdoor air pollutants and meteorology as well as outpatient visits for DED were collected. A time-stratified case-crossover approach was used to analyze the associations between ambient air pollutants and outpatient visits for DED. Among the 5062 DED patients studied, 65.45% were female and 34.55% were male. In the single-pollutant model, significant associations were observed between an increase of 10 μg/m³ in the concentrations of fine-particulate matter with a median aerometric diameter of less than 10 μm (PM₁₀), fine-particulate matter with a median aerometric diameter of less than 2.5 μm (PM₂.₅), sulfur dioxide (SO₂), nitrogen dioxide (NO₂), and carbon monoxide (CO) and outpatient visits for DED. These results were consistent with those of the multipollutant model. The strongest associations between air pollutants and patient visits were observed during the cold season and in patients aged 21–40. The significant association between air pollutants (PM₁₀, PM₂.₅, SO₂, NO₂, and CO) and DED outpatient visits indicates the importance of increased environmental protection.

This study examined the spatial and temporal variations of severe particulate pollution days (SPPDs) in China by using observed PM₂.₅ concentrations during April 2013 to February 2018 from the Ministry of Environmental Protection of China. SPPDs were defined as those with observed daily mean PM₂.₅ concentrations larger than 150 μg m⁻³. Observations showed that northern China had the highest number of SPPDs during the studied period. Since 2015, the number of SPPDs in northwestern China is comparable to or even higher than that observed in Beijing-Tianjin-Hebei (BTH). The highest numbers of SPPDs observed within BTH and the Yangtze River Delta (YRD) were 122 (33), 95 (17), 57 (15), 78 (18), and 31 (25) days in 2013, 2014, 2015, 2016, and 2017, respectively, indicating a general decreasing trend as a result of emission reduction measures. SPPDs occurred mainly from November to February in BTH and in December and January in the YRD. The major circulation patterns associated with large-scale SPPDs were analyzed by using principal component analysis. Five typical synoptic weather patterns were identified for BTH. The most dominant weather type (a cold high centered over the Xinjiang and Mongolian regions) for BTH was also responsible for most of the SPPDs in the YRD. These results have important implications for emission control strategies during SPPDs. Emission control measures can be applied once the dominant circulation patterns have been predicted.

Large amounts of short chain and medium chain chlorinated paraffins (SCCPs and MCCPs) are released into the environment during production and usage. However, compared to SCCPs, there is a significant lack of attention for MCCPs. In this work, 83 air samples, collected between 2012 and 2015 from the Tibetan Plateau, were analyzed to investigate the airborne levels and distributions of MCCPs, further to evaluate their potential long-range transport behavior on the alpine area. The total air MCCP concentrations at Shergyla Mountain and Lhasa were between 50 and 690 pg/m3 and 800–6700 pg/m3, respectively. At Shergyla Mountain, MCCP concentrations in the air appeared an increasing trend with altitude, which indicated that MCCPs could potentially possess the ability of “mountain cold trapping”. C14 and C15 congener groups were the dominant homologue groups. The mountain contamination potential (MCP) of different congener groups is closely related to their equilibrium partitioning coefficients between octanol and air (KOA), and water and air (KWA). Increasing MCCPs levels might be a potential threat to the environment and human exposure.

Baseline emission values of greenhouse gases were not well established for commercial poultry barns in cold regions, including Canada, due to a lack of well-designed field studies. Emission factors of carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O), were acquired for a commercial broiler barn and cage-layer barn in the Canadian Prairies climate. Between March 2015 and February 2016, monthly measurements throughout the year for the layer barn and over 6 flocks for the broiler barn, and diurnal measurements in the mild, warm, and cold seasons for both barns were conducted, respectively. The ventilation rate was estimated based on a CO₂ mass balance method; thus CO₂ emissions were quantified by the CIGR (2002) models. The CH₄ and N₂O emissions present at low levels from global perspective for both barns; the cold climate proved to be a major reason for the lower CH₄ emission from the layer barn. Considerable seasonal effect was observed only for N₂O emissions from the broiler barn, and for CH₄ and N₂O emissions from the layer barn, both with higher emissions in the mild and warm seasons than in the cold season. The big diurnal variations of CO₂ emissions for the layer barn demonstrated the uncertainty of the seasonal results by snapshot measurements and correction factors (from −20.9% to −22.5%) were obtained. Besides, the difference of CH₄ and N₂O concentrations and emissions as well as CO₂ concentrations between best-case (the first day after manure removal) and worst-case conditions (the last day before manure removal) was not obvious for the layer barn. Additionally, changes of temperature and ventilation rate were likely to have more impact on N₂O emission for the broiler barn and more impact on CH₄ emission for the layer barn than on the other two gas emissions, both with positive correlations.

Emissions from passenger cars are one of major sources that deteriorate urban air quality. This study presents characterization of real-drive emissions from three Euro 6 emission level passenger cars (two gasoline and one diesel) in terms of fresh particles and secondary aerosol formation. The gasoline vehicles were also characterized by chassis dynamometer studies. In the real-drive study, the particle number emissions during regular driving were 1.1–12.7 times greater than observed in the laboratory tests (4.8 times greater on average), which may be caused by more effective nucleation process when diluted by real polluted and humid ambient air. However, the emission factors measured in laboratory were still much higher than the regulatory value of 6 × 1011 particles km−1. The higher emission factors measured here result probably from the fact that the regulatory limit considers only non-volatile particles larger than 23 nm, whereas here, all particles (also volatile) larger than 3 nm were measured. Secondary aerosol formation potential was the highest after a vehicle cold start when most of the secondary mass was organics. After the cold start, the relative contributions of ammonium, sulfate and nitrate increased. Using a novel approach to study secondary aerosol formation under real-drive conditions with the chase method resulted mostly in emission factors below detection limit, which was not in disagreement with the laboratory findings.

Biological sulfate removal is challenging in cold climates due to the slower metabolism of mesophilic bacteria; however, cold conditions also offer the possibility to isolate bacteria that have adapted to low temperatures. The present research focused on the cold acclimation and characterization of sulfate-reducing bacterial (SRB) consortia enriched from an Arctic sediment sample from northern Finland. Based on 16S rDNA analysis, the most common sulfate-reducing bacterium in all enriched consortia was Desulfobulbus, which belongs to the δ-Proteobacteria. The majority of the cultivated consortia were able to reduce sulfate at temperatures as low as 6 °C with succinic acid as a carbon source. The sulfate reduction rates at 6 °C varied from 13 to 42 mg/L/d. The cultivation medium used in this research was a Postgate medium supplemented with lactate, ethanol or succinic acid. The obtained consortia were able to grow with lactate and succinic acid but surprisingly not with ethanol. Enriched SRB consortia are useful for the biological treatment of sulfate-containing industrial wastewaters in cold conditions.

659 water samples from springs and wells in the Sabatini and Vicano-Cimino Volcanic Districts (central Italy) were analyzed for arsenic (As), fluoride (F⁻) and radon (²²²Rn) concentrations. Waters mostly sourced from a shallow and cold aquifer hosted within volcanic rocks, which represents the main public drinking water supply. Cold waters from perched aquifers within sedimentary formations and thermal waters related to a deep hydrothermal reservoir were also analyzed. The highest concentrations of As and F⁻ were measured in the thermal waters and attributed to their enhanced mobility during water-rock interaction processes at hydrothermal temperatures. Relatively high concentrations of As and F⁻ were also recorded in those springs and wells discharging from the volcanic aquifer, whereas waters hosted in the sedimentary units showed significantly lower contents. About 60% (As) and 25% (F⁻) of cold waters from the volcanic aquifer exceeded the maximum allowable concentrations for human consumption. Such anomalously high levels of geogenic pollutants were caused by mixing with fluids upwelling through faulted zones from the hydrothermal reservoir. Chemical weathering of volcanic rocks and groundwater flow path were also considered to contribute to the observed concentrations. Cold waters from the volcanic aquifer showed the highest ²²²Rn concentrations, resulting from the high contents of Rn-generating radionuclides in the volcanic units. Approximately 22% of these waters exceeded the recommended value for human consumption. A specific Quality Index (QI), comprised between 1 (very low) and 4 (very high), was computed for each water on the basis of As, F⁻ and ²²²Rn concentrations and visualized through a spatial distribution map processed by means of geostatistical techniques. This map and the specific As, F⁻ and ²²²Rn maps can be regarded as useful tools for water management by local authorities to both improve intervention plans in contaminated sectors and identify new water resources suitable for human consumption.

Polycyclic aromatic hydrocarbons (PAHs) are organic compounds composed of at least two benzene rings. This paper reviews the characteristics, sources and health risk of airborne particulate PAHs in Chinese cities. The airborne particulate PAH concentrations varied from 3.35 to 910 ng m⁻³, with an average of 75.0 ng m⁻³, and the pollution level of PAHs in northern cities was generally higher than that in southern cities. The PAH concentrations in different cities underwent similar seasonal variations, with high concentrations in the winter and relatively low concentrations in the summer. Many factors, such as meteorological conditions and source emissions, influenced the spatiotemporal pattern of PAHs. High temperatures, frequent flow exchanges, abundant rainfall and strong solar radiation reduced the level of particulate PAHs in the atmosphere. The historical changes in the level of airborne particulate PAHs in four cities were analyzed. The PAH concentrations in Beijing and Taiyuan presented a trend of first increasing and then decreasing, while the level of particulate PAHs in Nanjing and Guangzhou had a decreasing tendency from year 2000–2015. The airborne particulate PAHs in cities were derived from several sources, including coal combustion, vehicle emissions, coking industries, biomass burning and petroleum volatilization. The results of a health risk assessment indicated that the incremental lifetime cancer risk (ILCR) for people in the northern cities was higher than that for people in the other regions, especially during the cold season. Moreover, adults were at greater risk than people in other age groups, and the health risk to females was slightly higher than that to males. The potential risk of airborne particulate PAH exposure was relatively high in some cities, and controlling PAH emissions at the source should be required to prevent pollution.

This study evaluated -for the first time- the occurrence and distribution of total Hg in abiotic (dissolved and particulate water fractions) and biotic (gills and muscle tissues of six commercial fish species) compartments within a South American coastal environment with anthropogenic pressure. This study dealt with environmental issues on developing countries which, as they are in continuous growth, face the highest rate of coastal transformation.Total Hg content was determined by acid digestion and measured using a cold vapor atomic absorption spectrophotometer. Results revealed that dissolved Hg exceeded the recommended levels for superficial saline waters in 67% of the cases. Hg concentrations varied among fish species and its tissues. The results suggested that metal burden in fishes achieved a mean maximum accumulation towards the muscle, with concentrations below the international maximum permitted values. The estimated daily intakes calculated suggest that people would not experience significant health risks through fish consumption.

Baseline concentration of total mercury (THg), organic extractable mercury and methylmercury (CH₃Hg) concentrations in sediments from the northeastern, eastern and southeastern parts of the Arabian Gulf were assessed. Surface sediments were collected from eleven stations from the coastal waters of Qatar. All analyses were performed on homogenised samples. Total mercury analysis was performed by Cold Vapour Atomic Absorption Spectrometry (CVAAS), and methylmercury was analysed by Cold Vapour Atomic Fluorescence spectrometry (CVAFS) after aqueous phase ethylation of the extracted samples. Total mercury (THg) in sediments varied from 8.0 μg/kg to 34.3 μg/kg. Methylmercury was detected in all stations and ranged from 1.46 μg/kg to 3.10 μg/kg accounting for 5.4% to 18.4% of total mercury. Total organic carbon (TOC) ranged from 0.16 to 0.72%, while Organic extractable mercury ranged from 1.55 μg/kg to 13.3 μg/kg. Analysis, the grain size within these sediments, was carried out previously paving the way for studying the influence of these parameters on the sedimentary mercury concentration. Speciation was also assessed, as were relations between the measured mercury fractions.