The modeling and health risk assessment of PM2.5 from Tema Oil Refinery

Fine particulate matters (PM_2.5) are known to pose serious health problems compared to other air pollutants. The current study employed air dispersion modeling system (AERMOD) to simulate the concentration of PM_2.5 from Tema Oil Refinery (TOR) and to assess the non-cancer risk and mortalities of the exposed population. In addition, the effects of local climatic factors on the distribution and concentration of PM_2.5 within the three main seasons (Major Raining Season (MRS), Low Raining Season (LRS) and Dry Season (DS)) were investigated. The AERMOD results showed that both 24-h (38.8 µg m^?3) and annual (12.6 µg m^?3) PM_2.5 concentration levels were in exceedance of the international limits. However, a decreasing trend in seasonal PM_2.5 concentrations was observed. Health risk assessment (HRA), indicated by hazard index (HI), revealed that the amount of Al₂O₃ present in the PM_2.5 caused a significant non-carcinogenic health risk to the exposed population (both adults and children) within the Metropolis (HI = 2.4 for adults and HI = 1.5 for children). Additionally, cardiopulmonary disease related mortalities due to PM_2.5 exposure (181 deaths for adults and 24 deaths for children) were found high compared to deaths caused by lung cancer (137 deaths for adults and 16 deaths for children).     

Apparent resistance to fall in forced vital capacity in children with increasing mass level of fine particulate: A physiological phenomenon

Abstract

Forced vital capacity (FVC) of children in the age group 10–12 years are reported as a function of quantum increase in PM_2.5 level in ambient air. The data are reported for the children in the categories based on their respective body mass index (BMI). FVC (% predicted) values decreased with increasing level of PM_2.5. The subjects are found to respond in a selective manner as plateau was observed for FVC values against some selected ranges of PM_2.5 concentration levels (74 µgm^?3 to >117 µgm^?3). To explain this unusual behavior, sac theory is proposed which explains the observations of FVC for subjects of all categories with different BMI values.     

Spatio-temporal modelling of particulate matter concentrations using satellite derived aerosol optical depth over coastal region of Chennai in India

The present study primarily focuses on describing aerosol optical depth (AOD), its distribution pattern and seasonal variation, and modelling Particulate Matter Concentrations in Chennai. The frequency distribution of AOD and PM_2.5 demonstrates that AOD can be used as a proxy for estimating PM_2.5 in the study region as the occurrence of AOD almost resonates with that of PM_2.5. The seasonal variation of AOD and PM_2.5 revealed that during the winter (October–January) and summer (February–May) seasons, AOD reasonably followed the trend of PM_2.5. However, during the monsoon period, AOD showed random variations. Different models like linear and non-linear regression models and machine learning models such as random forest (RF) have been developed for PM_2.5 estimation. The model's performance in different stations and seasons has been assessed. The effect of meteorology and other factors in the model has also been assessed. From linear and non-linear model analysis, AOD was a significant parameter in estimating PM_2.5. The Random Forest model was the stable model for the study region, with a model R² of 0.53 and an RMSE of 15.89 μg/m³. The inclusion of meteorological parameters like relative humidity, wind speed, and wind direction decreased the error in prediction by 17.45 μg/m³. The seasonal and spatial analysis indicates that the prediction capability of models varies with stations and seasons. The best performing model was found to be Model RF, and the model could explain about 53.14% of the variability in PM_2.5 concentration occurrence in the study region with a prediction error of 15.89 μg/m³.     

Characterization and modeling of atmospheric particles from sugarcane burning in Morelos,Mexico

Sugarcane processing emits atmospheric pollutants due to sugar mill operation as well as customary fields burning, intended to ease post harvesting land preparation and to minimize inherent wastes. Three atmospheric monitoring campaigns were conducted in the municipality of Zacatepec, Mexico. The data obtained were used to calibrate a Gaussian model built into a Geographic Information System, aimed at modeling a large number of plots from the burn database of the Zone of Zacatepec. During the sugarcane harvesting time and sugar mill operation, particulate matter (PM) concentrations went up to five- and threefold greater for PM₁₀ and PM_2.5, respectively, than during the period without the agro-industrial process. The PM₁₀ and PM_2.5 concentrations decreased between 39 and 43% when biomass burning activities stopped. In addition, measurements of 17 polycyclic aromatic hydrocarbons showed also the highest concentrations during the burning and sugar mill operating periods, where the most abundant of these compounds corresponded to those with the highest molecular weight displaying carcinogenic properties. Maps obtained of particles and benzo[a]pyrene equivalent concentrations allowed determining the populations mostly exposed, which are useful for the design of policies related to adequate conditions for agriculture burning, including the suitability of continuing with such practice.     

Seasonal patterns in biomass smoke pollution and the mid 20th-century transition from Aboriginal to European fire management in northern Australia

Aim Globally, most landscape burning occurs in the tropical savanna biome, where fire is a characteristic of the annual dry season. In northern Australia there is uncertainty about how the frequency and timing of dry season fires have changed in the transition from Aboriginal to European fire management. Location In the tropical eucalypt savannas that surround the city of Darwin in the northwest of the Northern Territory of Australia. Methods Our study had three parts: (1) we developed a predictive statistical model of mean mass (µg) of particulates 10 µm or less per cubic metre of air (PM₁₀) using visibility and other meteorological data in Darwin during the dry seasons of 2000 and 2004; (2) we tested the model and its application to the broader air shed by (a) matching the prediction of this model to PM₁₀ measurements made in Darwin in 2005, (b) matching the predictions to independent measurements at two locations 20 km to the north and south of Darwin and (c) matching peaks in PM₁₀ to known major fire events in the region (2000–01 dry seasons); and (3) we used the model to explore changes in air quality over the last 50 years, a period that spans the transition from Aboriginal to European land management. Results We demonstrated that visibility data can be used reliably as a proxy for biomass burning across the largely uncleared tropical savannas inland of Darwin. Validations using independent measurements demonstrated that our predictive model was robust, and geographically and temporally representative of the regional airshed. We used the model to hindcast and found that seasonal air quality has changed since 1955, with a trend to increasing PM₁₀ concentrations in the early dry season. Main conclusions The results suggest that the transition from Aboriginal to European land management has been associated with an increase in fire activity in the early months of the dry season.     

Effect of airborne <Emphasis Type="Italic">Alternaria</Emphasis> conidia,ozone exposure,PM<Subscript>10</Subscript> and weather on emergency visits for asthma in school-age children in Kolkata city,India

Alternaria is one of the important allergenic fungal spores having special role in childhood asthma. Aerodynamic particle of <10 μm diameter (PM₁₀) and ozone exacerbate respiratory conditions including asthma. There is no documentation determining the role of airborne concentration of Alternaria conidia, pollutants like PM₁₀ and ozone and weather on school-age (5–18 years) children causing life-threatening episodes requiring emergency hospitalization for asthma in the megacity of Kolkata, Eastern India. We examined the relationship of daily hospitalization for asthma in school-age children and daily concentration of outdoor Alternaria conidia, ozone, PM₁₀ and weather parameters in the atmosphere of Kolkata during 2010 using nonparametric generalized additive model (GAM). After a baseline survey (2008–2009), asthma hospitalization data for school-age children (based on case history and symptom-medication) were collected from two important city hospitals near study area in 2010. Daily Alternaria concentration was recorded using Burkard volumetric sampler. Its allergenic potential was confirmed by skin reactivity. Ozone and PM₁₀ concentration data were collected from West Bengal Pollution Control Board. The daily time series analyses of data were performed using GAM. There are two peak seasons of asthma hospitalization, one in spring-early summer (end of March to mid April) and other in autumn (mid September–October). In GAM analyses, Alternaria conidia, ozone and PM₁₀ were found to be significant both in spline and LOcal regrESSion smoothing method. Airborne Alternaria conidia, ozone and PM₁₀ in the city of Kolkata are found to have effect on school-age children with asthma and appear responsible for severe attacks leading to hospitalization.     

Oxidative stress-mediated epidermal growth factor receptor activation regulates PM2.5-induced over-secretion of pro-inflammatory mediators from human bronchial epithelial cells

BackgroundExposure to PM_2.5 has been associated with increased morbidity and mortality of lung diseases although the underlying mechanisms have not been fully uncovered. Airway inflammation is a critical event in the pathogenesis of lung diseases. This study aimed to examine the role of oxidative stress and epidermal growth factor receptor (EGFR) in PM_2.5-induced pro-inflammatory response in a human bronchial epithelial cell line, BEAS-2B.MethodsBEAS-2B cells were exposed to 0, 20, 50, 100 and 150 μg/ml of PM_2.5. Secretion of pro-inflammatory mediators including interleukin-6 (IL-6), IL-8 and IL-1β was determined using enzyme linked immunosorbent assay. Levels of intracellular reactive oxygen species (ROS) were determined using flow cytometry. Phosphorylation of the EGFR was examined with immunoblotting.ResultsPM_2.5 exposure increased the secretion of IL-6, IL-8, and IL-1β in a concentration-dependent fashion. Moreover, exposure to PM_2.5 elevated intracellular levels of ROS, and phosphorylation of the EGFR (Y1068). Pretreatment of BEAS-2B cells with either an antioxidant or a specific EGFR inhibitor significantly reduced PM_2.5-induced IL-6, IL-8 and IL-1β secretion, implying that both oxidative stress and EGFR activation were involved in PM_2.5-induced pro-inflammatory response. Furthermore, pre-treatment of BEAS-2B cells with an antioxidant significantly blunted PM_2.5-induced EGFR activation, suggesting that oxidative stress was required for PM_2.5-induced EGFR activation.ConclusionPM_2.5 exposure induces pro-inflammatory response in human bronchial epithelial cells through oxidative stress-mediated EGFR activation.     

Acute Effects of Particulate Matter and Black Carbon from Seasonal Fires on Peak Expiratory Flow of Schoolchildren in the Brazilian Amazon

Background

Panel studies have shown adverse effects of air pollution from biomass burning on children''s health. This study estimated the effect of current levels of outdoor air pollution in the Amazonian dry season on peak expiratory flow (PEF).

Methods

A panel study with 234 schoolchildren from 6 to 15 years old living in the municipality of Tangará da Serra, Brazil was conducted. PEF was measured daily in the dry season in 2008. Mixed-effects models and unified modelling repeated for every child were applied. Time trends, temperature, humidity, and subject characteristics were regarded. Inhalable particulate matter (PM₁₀), fine particulate matter (PM_2.5), and black carbon (BC) effects were evaluated based on 24-hour exposure lagged by 1 to 5 days and the averages of 2 or 3 days. Polynomial distributed lag models (PDLM) were also applied.

Results

The analyses revealed reductions in PEF for PM₁₀ and PM_2.5 increases of 10 µg/m³ and 1 µg/m³ for BC. For PM₁₀, the reductions varied from 0.15 (confidence interval (CI)95%: −0.29; −0.01) to 0.25 l/min (CI95%: −0.40; −0.10). For PM_2.5, they ranged from 0.46 (CI95%: −0.86 to −0.06) to 0.54 l/min (CI95%:−0.95; −0.14). As for BC, the reduction was approximately 1.40 l/min. In relation to PDLM, adverse effects were noticed in models based on the exposure on the current day through the previous 3 days (PDLM 0–3) and on the current day through the previous 5 days (PDLM 0–5), specially for PM₁₀. For all children, for PDLM 0–5 the global effect was important for PM₁₀, with PEF reduction of 0.31 l/min (CI95%: −0.56; −0.05). Also, reductions in lags 3 and 4 were observed. These associations were stronger for children between 6 and 8 years old.

Conclusion

Reductions in PEF were associated with air pollution, mainly for lagged exposures of 3 to 5 days and for younger children.     

Fine particulate matter air pollution and atherosclerosis: Mechanistic insights

BackgroundAtherosclerosis is a progressive disease characterized by the accumulation of lipids and fibrous plaque in the arteries. Its etiology is very complicated and its risk factors primarily include genetic defects, smoking, hyperlipidemia, hypertension, lack of exercise, and infection. Recent studies suggest that fine particulate matter (PM_2.5) air pollution may also contribute to the development of atherosclerosis.Scope of reviewThe present review integrates current experimental evidence with mechanistic pathways whereby PM_2.5 exposure can promote the development of atherosclerosis.Major conclusionsPM_2.5-mediated enhancement of atherosclerosis is likely due to its pro-oxidant and pro-inflammatory effects, involving multiple organs, different cell types, and various molecular mediators.General significanceStudies about the effects of PM_2.5inhalation on atherosclerosis may yield a better understanding of the link between air pollution and major cardiovascular diseases, and provide useful information for policy makers to determine acceptable levels of PM_2.5 air quality. This article is part of a Special Issue entitled Air Pollution, edited by Wenjun Ding, Andrew J. Ghio and Weidong Wu.     

A dynamic analysis of air pollution emissions in China: Evidence from nonparametric additive regression models

PM_2.5 emissions not only have serious adverse health effects, but also impede transportation activities, especially in air and highway transport. As a result, PM_2.5 emissions have become a public policy concern in China in recent years. Currently, the vast majority of existing researches on PM_2.5 are based on natural science perspective. Very few economic studies on the subject have been conducted with linear models. This paper adopts provincial panel data from 2001 to 2012, and uses the STIRPAT model and nonparametric additive regression models to examine the key driving forces of PM_2.5 emissions in China. The results show that the nonlinear effect of economic growth on PM_2.5 emissions is consistent with the Environmental Kuznets Curve (EKC) hypothesis. The nonlinear impact of urbanization exhibits an inverted “U-shaped” pattern due to the rapid development of urban real estate in the early stages and the strengthening of environmental protection measures in the latter stage. Coal consumption follows an inverted “U-shaped” relationship with PM_2.5 emissions owing to massive coal consumption at the beginning and efforts to optimize the energy structure as well as technological progress in clean energy in the latter stages. The nonlinear inverted “U-shaped” impact of private vehicles may be due to the different roles of scale, structural and technical effects at different stages. However, energy efficiency improvement follows a positive “U-shaped” pattern in relation to PM_2.5 emissions because of differences in the scale of the economy and the speed of technological progress at different times. As a result, the differential dynamic effects of the driving forces of PM_2.5 emissions at different times should be taken into consideration when initiating policies to reduce PM_2.5 emissions in China.     

DDAH1 plays dual roles in PM2.5 induced cell death in A549 cells

BackgroundDimethylarginine dimethylaminohydrolase 1 (DDAH1) is an enzyme that can degrade asymmetric dimethylarginine (ADMA), an endogenous nitric oxide synthase (NOS) inhibitor. Emerging evidence suggests that alterations in the ADMA–DDAH1 pathway are involved in environmental pollution induced airway inflammation. However, the role of DDAH1 in protection against cytotoxicity of ambient airborne particulate matter is unclear.MethodsWe examined the influence of DDAH1 expression on oxidative stress and cell apoptosis in human type II alveolar epithelial A549 cells exposed to PM_2.5 (particulate matter with an aerodynamic diameter less than 2.5 μM).ResultsWe found that PM_2.5 exposure for 48 h significantly decreased DDAH1 expression. However, knockdown of DDAH1 prior to PM_2.5 exposure actually attenuated the cytotoxicity of PM_2.5. Cytoprotection in DDAH1 deficient cells was due to increased reactive oxygen species, activation of PI3K–AKT and mitogen-activated protein kinase (MAPK) pathways, subsequent activation of nuclear factor erythroid-2-related factor 2 (Nrf2) and this caused a subsequent reduction in PM_2.5 induced oxidative stress relative to control. DDAH1 depletion also repressed the induction of inducible NOS (iNOS) in PM_2.5-exposed cells and knockdown of iNOS protected cells against PM_2.5 induced cell death. Interestingly, overexpression of DDAH1 also exerted a protective effect against the cytotoxicity of PM_2.5 and this was associated with a reduction in oxidative stress and upregulation of the anti-apoptotic protein Bcl-2.ConclusionsOur data indicate that DDAH1 plays dual roles in protection against cytotoxicity of PM_2.5 exposure, apparently by limiting PM_2.5 induced oxidative stress.General significanceOur findings reveal new insights into the role(s) of the DDAH1/ADMA in pulmonary protection against airborne pollutants. This article is part of a Special Issue entitled Air Pollution, edited by Wenjun Ding, Andrew J. Ghio and Weidong Wu.     

PM2.5 exposure-induced autophagy is mediated by lncRNA loc146880 which also promotes the migration and invasion of lung cancer cells

BackgroundEvidence shows that individuals who are under long-term exposure to environmental PM_2.5 are at increased risk of lung cancer. Various laboratory experiments also suggest several mechanistic links between PM_2.5 exposure and lung carcinogenesis. However, a long non-coding RNA (lncRNA) mediated pathogenic change after PM_2.5 exposure and its potential roles in tumorigenesis and disease progression have not been reported.MethodsCytotoxicity induced by PM_2.5 was assessed by using scanning electron microscopy and transmission electron microscopy. ROS generation, autophagy, and metastasis induced by PM_2.5 were detected by using comprehensive approaches. Expression of lncRNA-loc146880 and lc3b (autophagy marker) in A549 cells, lung tissue and serum were determined by RT-PCR and Western blotting.ResultsPM_2.5 could be internalized into lung cancer cells, resulting in marked increases in ROS levels and autophagy. ROS may be responsible for increased expression of loc146880 which further up-regulates autophagy. Both loc146880 and autophagy could promote lung tumor cell migration, invasion and EMT. In addition, a positive correlation was observed between loc146880 expression and lc3b levels in tumor tissues and serum of lung cancer patients.ConclusionTaken together, our data suggest that PM_2.5 exposure induces ROS, which activates loc146880 expression. The lncRNA, in turn, up-regulates autophagy and promotes the malignant behaviors of lung cancer cells.General significanceThe results show the toxicological effects of PM_2.5 in lung tumor progression and metastasis.     

Microbial community structure in PM2.5 affected by burning fireworks during the 2019 Spring Festival in Guilin,a touristic city in South China

Setting off fireworks during the Spring Festival are a popular traditional custom and recreational activity in China. Intensity of firecracker burning can quickly deteriorate air quality. Airborne bacteria are also important constituents of atmospheric particulate matter and contain many pathogens. However, few studies have reported variations in the bacterial community structure in PM_2.5 during firecracker burning. In this study, PM_2.5 samples were collected at four different sites in the city of Guilin during Spring Festival from February 4 to 8, 2019 and a high-throughput sequencing technology was used to investigate the variations of bacterial diversity and community structure in PM_2.5. The results revealed that Proteobacteria was the predominant bacterial phylum comprising 94.3% of the total sequences, followed by Firmicutes, Actinobacteria, Bacteroidetes, and Deinococcus-Thermus. At the genus level, the top five abundant genera accounted for 81.8% of the total sequences. The proportions of major genera (Cupriavidus, Sphingobium, Brevundimonas, Sphingomonas, and Pseudomonas) were apparently affected by firecracker burning. In particular, the relative abundance of Brevundimonas genus increased dramatically from 3.2 to 60.1% at the Huaqiaonongchang (HQ) sampling site during intense firework burning, while those of other major genera and potential pathogens detected including Pseudomonas, Acinetobacter, and Serratia decreased. In addition, compared with the normal condition, the number of operational taxonomic units and the diversity and richness of microorganisms in PM_2.5 samples decreased apparently. Pearson correlation results also revealed that they were negatively correlated with the NO₂, SO₂, and PM_2.5 concentrations.

     

Direct effects of airborne PM2.5 exposure on macrophage polarizations

BackgroundExposure of atmospheric particulate matter with an aerodynamic diameter less than 2.5 μm (PM_2.5) is epidemiologically associated with illnesses. Potential effects of air pollutants on innate immunity have raised concerns. As the first defense line, macrophages are able to induce inflammatory response. However, whether PM_2.5 exposure affects macrophage polarizations remains unclear.MethodsWe used freshly isolated macrophages as a model system to demonstrate effects of PM_2.5 on macrophage polarizations. The expressions of cytokines and key molecular markers were detected by real-time PCR, and flow cytometry. The specific inhibitors and gene deletion technologies were used to address the molecular mechanisms.ResultsPM_2.5 increased the expression of pro-inflammatory cytokines granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin-6 (IL-6), interleukin-1β (IL-1β), tumor necrosis factor alpha (TNFα). PM_2.5 also enhanced the lipopolysaccharide (LPS)-induced M1 polarization even though there was no evidence in the change of cell viability. However, PM_2.5 significantly decreased the number of mitochondria in a dose dependent manner. Pre-treatment with NAC, a scavenger of reactive oxygen species (ROS), prevented the increase of ROS and rescued the PM_2.5-impacted M1 but not M2 response. However, mTOR deletion partially rescued the effects of PM_2.5 to reduce M2 polarization.ConclusionsPM_2.5 exposure significantly enhanced inflammatory M1 polarization through ROS pathway, whereas PM_2.5 exposure inhibited anti-inflammatory M2 polarization through mTOR-dependent pathway.General significanceThe present studies suggested that short-term exposure of PM_2.5 acts on the balance of inflammatory M1 and anti-inflammatory M2 macrophage polarizations, which may be involved in air pollution-induced immune disorders and diseases. This article is part of a Special Issue entitled Air Pollution, edited by Wenjun Ding, Andrew J. Ghio and Weidong Wu.     

北京西山典型城市森林内PM_(2.5)动态变化规律

城市森林内PM2.5浓度的状况可以直接反映城市森林对PM2.5的净化效果,也是居民休闲游憩关心的森林环境问题。选择北京西山3种典型的游憩型城市森林,通过对林内PM2.5浓度一年四季昼夜24h内变化的同步观测,分析了不同类型城市森林内PM2.5浓度的季节变化、日变化以及影响因素,结果表明:(1)北京西山3种游憩林内PM2.5浓度多数时候远低于城区对照值,在春、夏、秋三季都达到了国家城市化地区的标准,甚至在春季、秋季还达到了国家一类地区的标准。(2)城市森林在不同季节对PM2.5的净化效果存在差异,林内PM2.5浓度总体上呈现冬季夏季秋季春季的规律。(3)林内PM2.5浓度在一天24h内有很大变化波动,夜间浓度总体上高于白天,日变化曲线近似呈"双峰双谷"型,两个高峰出现在夜晚和早上,两个低谷出现在凌晨和中午前后。一年四季白天低谷出现时间有所不同,春季15:00左右、夏季13:00—17:00、秋季13:00—15:00、冬季9:00—11:00。(4)PM2.5在不同类型游憩林内的变化趋势和浓度值存在一定差异。郁闭度较大的侧柏林夜间PM2.5浓度总体上高于其它两种林型,其高峰和低谷出现时间延迟,高峰值大,高峰期持续时间长,且这种规律在秋季表现得更明显。(5)基于上述研究认为,北京西山城市森林为居民在PM2.5污染比较突出的都市背景下提供了一个相对清洁、健康的森林游憩环境,春季、夏季、秋季全天以及冬季9:00—11:00均是森林中PM2.5状况健康而适宜外出游憩的时段。     

Use of LCA indicators to assess Iranian rapeseed production systems with different residue management practices

In this study the environmental profile of Iranian rapeseed cultivation was analysed with a Life Cycle Assessment (LCA) approach, in order to identify the hot spots of the system. Also, in order to apply environmental indicators for agricultural decision making purposes, the environmental burden of different residue management practices were compared. Primary data were collected from 150 rapeseed farms from the Iranian Mazandaran province. The system considers a cradle-to-farm gate boundary, and the functional unit was regarded as being one Mg of rapeseed production. The LCA results indicate that the global warming potential amounts to 1181.6 kg CO_2eq Mg⁻¹. Also, the acidification and eutrophication potentials were found to be 23.3 kg SO_2eq Mg⁻¹ and 18 kg PO₄³_eq Mg⁻¹, respectively. The results also reveal that environmental emissions of crop production were significantly affected by residue management practices. Specifically, rapeseed residue removal from the field is the most environmentally-friendly practice. This is followed by a scenario involving residue incorporation in the soil. The practice of burning such residue entails the highest environmental emissions. In conclusion, reducing the consumption of chemical fertilisers, especially nitrogen based ones, is important for decreasing the environmental footprints in the area. Furthermore, avoiding crop residue burning and developing rapeseed-bean rotation are favourable management strategies for establishing more environmentally-friendly rapeseed production systems in the region.     

Production of Bio-Energy from Pig Manure: A Focus on the Dynamics Change of Four Parameters under Sunlight-Dark Conditions

This study investigated the effect of sunlight-dark conditions on volatile fatty acids (VFAs), total ammonium nitrogen (TAN), total alkalinity (TA) and pH during pig manure (PM) digestion and then the subsequent influence on biogas yield of PM. PM₁ and PM₂ were performed in a transparent reactor and a non-transparent reactor, respectively. Two sets of experiments were conducted with a temperature of 35.0±2.0 °C and a total solid concentration of 8.0% to the digestion material. The dynamic change of the four parameters in response to sunlight-dark conditions resulted in variations of the physiological properties in the digester and affected the cumulative biogas production (CBP). PM₁ obtained higher CBP (15020.0 mL) with a more stable pH and a lower TAN concentration (1414.5 mg/L) compared to PM₂ (2675.0 mL and 1670.0 mg/L, respectively). The direct path coefficients and indirect path coefficients between the four parameters and CBP were also analyzed.     

Plastic pollution in croplands threatens long‐term food security

Plastic pollution is a global concern given its prevalence in aquatic and terrestrial ecosystems. Studies have been conducted on the distribution and impact of plastic pollution in marine ecosystems, but little is known on terrestrial ecosystems. Plastic mulch has been widely used to increase crop yields worldwide, yet the impact of plastic residues in cropland soils to soil health and crop production in the long term remained unclear. In this paper, using a global meta‐analysis, we found that the use of plastic mulch can indeed increase crop yields on average by 25%–42% in the immediate season due to the increase of soil temperature (+8%) and moisture (+17%). However, the unabated accumulation of film residues in the field negatively impacts its physicochemical properties linked to healthy soil and threatens food production in the long term. It has multiple negative impacts on plant growth including crop yield (at the mean rate of ?3% for every additional 100 kg/ha of film residue), plant height (?2%) and root weight (?5%), and soil properties including soil water evaporation capacity (?2%), soil water infiltration rate (?8%), soil organic matter (?0.8%) and soil available phosphorus (?5%) based on meta‐regression. Using a nationwide field survey of China, the largest user of plastic mulch worldwide, we found that plastic residue accumulation in cropland soils has reached 550,800 tonnes, with an estimated 6%–10% reduction in cotton yield in some polluted sites based on current level of plastic residue content. Immediate actions should be taken to ensure the recovery of plastic film mulch and limit further increase in film residue loading to maintain the sustainability of these croplands.     

Seasonal Variation in Schools’ Indoor Air Environments and Health Symptoms among Students in an Eastern Mediterranean Climate

The indoor air quality (IAQ) in classrooms highly affects the health and productivity of students. This article aims to clarify seasonal variation in indoor environment and sick building syndromes (SBS) symptoms in an Eastern Mediterranean climate. A series of field measurements were conducted during the fall and winter seasons from October 2011 to March 2012 in 12 naturally ventilated schools located in the Gaza Strip. Data on environmental perception and health symptoms were obtained from 724 students by using a validated questionnaire. The results showed that indoor PM₁₀ and PM_2.5 concentrations were 426.3 ± 187.6 μg/m³ and 126.6 ± 94.8 μg/m³, respectively. The CO₂ concentrations and ventilation rate widely exceeded their reference values during the winter season. The prevalence rates of general symptoms were relatively high at baseline assessment in the fall season and increased significantly during follow-up in the winter season. Significant increases in disease symptoms such as mucosal irritation and pre-existing asthma symptoms among students could be related to poor indoor air quality. Five distinct groups of SBS symptoms from factor analysis of students’ related symptoms were significantly correlated with PM₁₀ and PM_2.5, CO₂, ventilation rate, and indoor temperature. As vulnerable children, this situation negatively affects their school performance and health.