Search Results (9,707)

Indoor air quality (IAQ) in schools significantly affects health and academic performance; however, effective interventions for poor air quality remain limited, particularly in settings with restricted natural ventilation. This study evaluated the effectiveness of ventilation-type air purifiers in improving classroom IAQ in a South Korean elementary school. PM₁₀, PM_2.5, and CO₂ concentrations were monitored over 18 days (14–31 May 2021) in two classrooms—one equipped with a ventilation-type air purifier and the other serving as a control. In the classroom with the air purifier, daily average concentrations of PM₁₀, PM_2.5, and CO₂ decreased by 23.7%, 22.8%, and 21.1%, respectively, from baseline levels. The air purifier effectively reduced pollutant infiltration during periods of severe outdoor air pollution and stabilized pollutant levels during active class hours. Its efficacy was particularly prominent under conditions of restricted natural ventilation, high indoor activity, and fluctuating outdoor pollution levels. IAQ varied significantly between weekdays and weekends; pollutant levels were higher on weekdays due to occupancy and classroom activities, whereas weekends exhibited reduced concentrations. These findings suggest that ventilation-type air purifiers provide a viable strategy for improving IAQ in schools with limited ventilation. Future research should examine their long-term performance across different seasons and architectural settings. Full article

Human actions have significantly modified the global environment, leading to adverse effects on public health. Pregnant women, being particularly vulnerable, face increasing risks as climate change continues to raise concerns about its influence on maternal and birth outcomes. As climate change persists, exploration of its effects on maternal birth outcomes is of increasing importance. This study investigates two particularly salient factors (temperature and ozone pollution) and their impact on birth outcomes in Phoenix, Arizona. With its unique mountainous terrain, semi-arid climate, and high temperatures, Phoenix creates conditions that expose residents to elevated levels of pollutants and extreme heat. This paper uses a retrospective cohort study of pregnant mothers who delivered during October 2018–December 2020 at St. Joseph’s Hospital and monthly temperature data during the last trimester of each patient’s pregnancy. These data were gathered from the National Weather Service and Ozone Air Quality Index data from the Arizona Department of Environmental Quality. Our analyses revealed that the highest levels of ozone and elevated temperature exposure were both independently associated with lower birth weights. Furthermore, we found that ozone mediated the effect of temperature on birth weight outcomes (controlling for participants’ sociodemographics), demonstrating that the relationship between temperature and birth weight was explained through increases in ozone pollution. Full article

The main objective of the research presented in this article was to analyze the composition of exhaust gases from passenger cars undergoing periodic inspections and to determine the influence of vehicle age, mileage and the applicable EURO emission standard on the level of emissions of individual components of exhaust gases and thus on the environment. The research was carried out at the District Vehicle Inspection Station in Nowy Sącz, using methods for analyzing the composition of exhaust gases and smoke opacity. The results obtained make it possible to assess whether exhaust emission diagnostics can form the basis for the implementation of a sustainable road transport policy. The study showed that older vehicles emit higher concentrations of carbon monoxide (CO) and hydrocarbons (HC), and diesel cars manufactured before 2010 are characterized by increased smoke opacity. A reliable analysis of the emissions performance of vehicles on the road enables more effective measures to be taken to reduce emissions and improve air quality through regulation, the introduction of clean traffic zones and raising environmental awareness among drivers. This is especially important in regions with specific geographical conditions, such as the Nowy Sącz district, where the terrain—Nowy Sącz is located in a basin surrounded by mountain ranges—favors the accumulation of pollutants and hinders the natural air circulation, leading to the long-term persistence of smog. Full article

Biodiesel has a higher oxygen content and a higher cetane number, which can compensate for the intake oxygen deficiency in diesel engines in a plateau environment to a certain extent. However, the decreased air density makes biodiesel fuel spray atomization and evaporation more difficult due to its higher density and kinematic viscosity, reducing the quality of the air-fuel mixture. The investigations in this study focus on the effects of biodiesel blending ratios and their coupling with injection timing on diesel engine performances under varying altitude conditions. The results show that as the altitude increases, using a high proportion of biodiesel-blended fuel results in a lower degree of torque reduction. The torque reduction of B100 is 14% lower than that of baseline at an altitude of 4500 m. In addition, when the altitude increases by 2000 m, the optimal fuel injection timing is delayed by 4° CA, regardless of the biodiesel blending ratio. The low-temperature combustion heat release ratio of biodiesel engines slightly increases with the delay of injection time, which is increased with the biodiesel blending ratio. For B100 fuel, increasing the pilot injection quantity under high-altitude conditions helps to improve the heat release rate during the early and late stages of combustion and reduce expansion losses. Full article

This article explores the integration of Maintenance 4.0 into HVAC (heating, ventilation, and air conditioning) systems, highlighting its essential role within the framework of Industry 4.0. Maintenance 4.0 utilizes advanced technologies such as artificial intelligence and IoT sensing technologies. It also incorporates sophisticated data management techniques to transform maintenance strategies into HVAC and indoor ventilation systems. These innovations work together to enhance energy efficiency, air quality, and overall system performance. The paper provides an overview of various Maintenance 4.0 frameworks, discussing the role of IoT sensors in real-time monitoring of environmental conditions, equipment health, and energy consumption. It highlights how AI-driven analytics, supported by IoT data, enable predictive maintenance and fault detection. Additionally, the paper identifies key research gaps and challenges that hinder the widespread implementation of Maintenance 4.0, including issues related to data quality, model interpretability, system integration, and scalability. This paper also proposes solutions to address these challenges, such as advanced data management techniques, explainable AI models, robust system integration strategies, and user-centered design approaches. By addressing these research gaps, this paper aims to accelerate the adoption of Maintenance 4.0 in HVAC systems, contributing to more sustainable, efficient, and intelligent built environments. Full article

In an air-conditioned multinational graduate students’ office in Japan during the winter season, we examined indoor environmental conditions, occupants’ perceptions, and their acceptance levels over five consecutive days. Indoor air quality (IAQ) acceptance peaked on the third day, coinciding with the most favourable thermal sensation vote, which was “neutral” at a geometric mean indoor temperature of 25.1 °C. Aural comfort received the lowest acceptance due to ongoing construction work, but did not significantly impact overall IEQ acceptance, thus suggesting that unacceptable aspects of indoor environmental quality (IEQ) can be offset by acceptable aspects. IAQ and thermal comfort compensated for its effects, offering insights into occupants’ environmental tolerance. IAQ sensation votes and visual comfort votes exhibit a strong relationship with overall comfort, as indicated by their respective R² values. However, variations in overall comfort are primarily explained by IAQ, which has the highest R² value of 0.50, suggesting that IAQ accounts for 50% of the changes in overall occupant comfort. Non-Japanese participants had lower IEQ acceptance and a significantly higher number of complaints than Japanese participants more so in visual comfort where acceptable luminance levels were higher in Japan than other participants’ countries of origin. Thermal comfort was mutually highly accepted by both groups. Nose and eye irritation were significantly experienced by the international participants due to low RH levels but experiencing loss of concentration and lethargy was comparable in both groups (p > 0.05, t-test). We recommend global coherence in indoor environmental quality standards as is the case with drinking water standards for public health protection and seamless transitions in new indoor environments. Full article

During the South Asian Summer Monsoon (SASM), intense large-scale uplift and strong deep convective activity over South Asia lead to the formation of a high aerosol concentration zone in the Upper Troposphere and Lower Stratosphere (UTLS), known as the Asian Troposphere Aerosol Layer (ATAL), which appears from June to August. ATAL not only influences the exchange processes of material and energy between the troposphere and stratosphere, but also affects the global climate by altering radiation, cloud formation, and precipitation processes. Therefore, examining the spatiotemporal distribution and climate impacts of ATAL is essential for understanding climate change and evaluating the feasibility of geoengineering. This study systematically reviews research progress on the three-dimensional spatiotemporal distribution, trends, sources, and climatic effects of ATAL. Findings reveal a prominent aerosol layer at the top of the Asian troposphere, and the SASM region potentially serving as a critical conduit for constituents of the boundary layer to reach the stratosphere. However, simulated ATAL components differ significantly across models, particularly in terms of vertical distribution patterns. The precise three-dimensional structure and long-term evolution of ATAL remain unclear, presenting challenges for assessing its climate impact. To advance the understanding of the roles of ATAL in climate change, three future research directions are proposed. Full article

To explore the characteristics of PM_2.5 and assess the health risks to residents in Shijiazhuang before and during the heating period in 2019, 2020 and 2021, the hourly concentrations of PM_2.5 and its nine selected trace elements were determined. The results showed that the mass concentrations of PM_2.5 were 80.32 ± 50.21 μg m⁻³ (2019), 69.97 ± 41.91 μg m⁻³ (2020) and 58.70 ± 41.97 μg m⁻³ (2021) during the heating period, representing greatly improved air quality. The PM_2.5 levels in the heating period were 1.04~1.60 times greater than those before the heating period, while the total selected trace element concentrations were about 1.44~1.97 times higher, indicating that strict control for PM_2.5 in the heating period should be imposed. The overall hazard quotient (HQ) of the nine selected trace elements in the heating period were 1.08~1.42 times higher than those before the heating period, while the total cancer risks (CR) were decreased by 29.04% (2020) and 3.50% (2021). There were high health risks not only in local areas, but also in the south of Hebei, the north of Henan, and southern and central Shanxi. The health risks increased by 1.21~2.26 times from clean levels to heavy pollution levels. The leading element of HQ was Mn, while the dominant elements of CR varied from As to Co. Increases in PM_2.5 concentrations and HQ from before the heating period to during the heating period were observed, and there was even an inverse CR change between before the heating period and during the heating period, further identifying that air pollution control was efficient. Full article

Perovskite solar cells have garnered significant attention due to their outstanding optoelectronic properties, ease of fabrication, and cost-effectiveness, making them a promising candidate for next-generation photovoltaic technologies. However, CsPbIBr₂-based perovskites currently face critical challenges regarding their limited efficiency and relatively poor long-term stability, hindering their broader commercial applications. In this study, we systematically investigated the morphological effects induced by different solvents, including dimethylformamide (DMF), N-methyl-2-pyrrolidone (NMP), and dimethyl sulfoxide (DMSO), on the formation and characteristics of lead bromide (PbBr₂) complexes. Further optimization was achieved through the innovative incorporation of trimesoyl chloride (TMC) doping into the perovskite precursor solution. The optimized precursor solution was subsequently processed using a spin-coating and annealing method, resulting in high-quality CsPbIBr₂ perovskite thin films with improved morphological and optoelectronic properties. The experimental results demonstrated a remarkable enhancement in power conversion efficiency (PCE), with an increase from an initial value of 6.2% up to 10.2%. Furthermore, the optimized CsPbIBr₂ solar cells exhibited excellent stability, maintaining over 80% of their initial efficiency after continuous aging for 250 h in ambient air conditions. This study presents an effective strategy for the controlled morphological and compositional engineering of wide-bandgap perovskite materials, providing a significant step forward in the advancement of perovskite photovoltaic technology. Full article

As cement production causes large amounts of CO₂ emissions and is not sustainable, there is a growing worldwide interest in developing cleaner construction materials by reducing carbon emissions and reusing existing industrial waste. Also, antimicrobially active construction materials are gaining attention due to enhancing structural longevity. By preventing microbial growth, these materials help to improve indoor air quality and occupant health. Geopolymer mortars/concretes (GPM/GPC) with high mechanical, physical and durability properties are considered as an eco-friendly alternative to ordinary Portland cement (OPC) mortars/concretes. In this study, the composition, microstructural, mechanical and antimicrobial properties of geopolymers produced at different curing temperatures (60, 80, 100 and 120 °C) were investigated. Low-lime fly ash was used as binder and sodium silicate and sodium hydroxide were used as the alkaline solution in geopolymer production. Although X-ray fluorescence (XRF) results showed an increase in geopolymerization products with increasing temperature, SEM analysis showed that the crack formation that occurs in the microstructure of geopolymers cured above 100 °C leads to decreased mechanical properties. The strength and antimicrobial performance test results for geopolymer mortars showed that the optimum temperature was 100 °C, and the highest compressive strength (48.41 MPa) was reached at this temperature. A decrease in strength was observed due to cracks occurring in the microstructure at higher temperatures. The agar diffusion method was used to determine the antimicrobial activity of GPMs against four bacteria and one fungus species. The antimicrobial activity test results showed that the samples subjected to thermal curing at 100 °C formed the highest inhibition zones (38.94–49.24 mm). Furthermore, the alkalinity of the components/mixtures has a direct relationship with antimicrobial activity. As a result, GPMs with superior antimicrobial and mechanical properties can be considered as promising building materials, especially for construction applications where hygiene is a priority and for structures that are likely to be exposed to microbial corrosion. Full article

Agrivoltaic offers a promising solution to integrate photovoltaic energy production with ongoing agricultural activities. This research investigates the impact of agrivoltaic on food security, using a transdisciplinary approach to study the responses of crop production in terms of biomass and food quality produced. Mainly chicory plants were grown in full sunlight (control plot) and shade plots generated by potential photovoltaic panels. Two water regimes (high and low water supply) were used to analyze variations in food security in both plots. The results showed that agrivoltaic systems effectively mitigate crop water stress caused by high temperatures and heat waves, improving food security by increasing biomass production and preserving food quality. While previous research has attributed the benefits of agrivoltaics primarily to improved soil moisture, this study demonstrates that the positive effects are primarily driven by differences in light intensity and air temperature between the shaded and control plots. The results have strong implications for water resource management, showing that agrivoltaics can reduce water use by approximately 50% compared to traditional agroecosystems without compromising food security. Agrivoltaics can address the challenges of water scarcity due to declining rainfall and reduce production costs associated with water use. Properly designed agrivoltaic systems offer a cleaner, more sustainable alternative to traditional agricultural practices, helping to adapt agriculture to climate change. Full article

Air Quality (AQ) and the management of low-emission zones are critical issues in densely populated urban areas. In such environments, human activity significantly impacts AQ, prompting increased efforts to monitor it using a range of devices. Traditional Air Quality monitoring relies on regulated stations, which are often scarce due to high costs, leaving many areas unmonitored. Low-cost sensors offer a promising solution by enabling the higher-spatial-resolution monitoring of pollution levels. In this article, we present the results of a case study conducted in an urban setting where AQ is affected by human activity, particularly during Las Fallas, Valencia’s most renowned festival, which has been declared an Intangible Cultural Heritage of Humanity by UNESCO. The festival features widespread bonfires, firecrackers and large crowds, all of which contribute to worsening air pollution. In this context, we evaluate the performance of the off-the-shelf, low-cost ZPHS01B multisensor module in a real deployment. This module is capable of monitoring Temperature (T), Relative Humidity (RH), Particulate Matter (PM), CO, ${\mathrm{CO}}_2$, ${\mathrm{NO}}_2$, ${\mathrm{O}}_3$, ${\mathrm{CH}}_2$O and Volatile Organic Compounds. We analyze the features and properties of these sensors. In our deployments, the ZPHS01B module is connected to an ESP32 microcontroller and assembled into an AQ Internet of Things (IoT) node. We present AQ monitoring results from the festival and compare the measurements with those from regulated AQ monitoring stations, used as a reference. Additionally, we evaluate the power consumption of this AQ IoT node, providing its electrical operating characteristics and considering the use of duty cycles to reduce consumption while maintaining sensor stability. We conclude that this module offers promising capabilities for identifying pollution risk zones and opens the door to new research opportunities, particularly in efficient sensor calibration and AQ parameter prediction. Full article

Biomass burning (BB) results from complex interactions between ecosystems, humans, and climate, releasing large amounts of gases and particles. Accurate BB emission estimates are essential for air quality, climate studies, and impact assessments. Various existing bottom-up BB emission inventories show significant discrepancies, varying by factors of 2 to 4 due to uncertainties in burned areas (BAs), emission factors (EFs), and vegetation parameters such as biomass density (BD) and burning efficiency (BE). Here, we investigate the role of vegetation parameters in these discrepancies in Africa. Two BB emission inventories, AMMABB-like (African Monsoon Multidisciplinary Analysis Biomass Burning) and GFED-like (Global Fire Emission Database) were developed for Organic Carbon (OC) and Black Carbon (BC). Both inventories used identical fire products, vegetation maps, and EF but different BD and BE values. Results highlight substantial differences in BD and BE, with relative gaps ranging from 44% to 85.12%, explaining the observed differences between BB emission inventories. Key vegetation classes responsible for BB emissions were identified. Discrepancies of 2.4 to 3.9 times were observed between AMMABB-like and GFED4-like, with higher values in the Southern Hemisphere. Better BD and BE estimates with regional distinctions for both hemispheres would improve BB emission accuracy in Africa. Full article

Background: Velopharyngeal insufficiency (VPI) is a failure of the sphincter mechanism, causing speech patterns like hypernasality and decreased intelligibility. Causes include structural, neurologic, and mechanical issues. Treatment options include non-surgical and surgical interventions, but complications can arise. A new approach using the buccal flap (BF) has been suggested for palatal length augmentation. This systematic review assessed speech outcomes after BF palatal lengthening. Methods: A thorough investigation was conducted by methodically reviewing numerous databases, including PubMed, Scopus, Web of Science, and Embase, until December 2024. The goal of our analysis was to find studies that assess the short- and long-term efficacy of BF on speech outcomes on patients with VPI. We used the NIH Quality Assessment Tool to assess the quality of the evidence, ensuring the dependability of the results reached during these investigations. Results: This systematic review identified 23 studies (total sample size of 995) that assessed the speech outcomes of BF on VPI. The BF significantly improves speech outcomes in patients with VPI. Hypernasality improved significantly post-surgery, with outcomes measured using different scales and methods, including both subjective and objective tools. Benefits were observed within three months postoperatively, with sustained benefits up to 15 months in several studies. Speech intelligibility also improved notably, with mean differences up to 1.09 (p < 0.001). Reductions in audible nasal air emissions were observed, though some variability was noted across studies. Secondary outcomes, including better velopharyngeal closure and decreased facial grimacing, further highlight its efficacy. However, inconsistent findings for nasal turbulence and limited long-term data suggest that benefits may plateau over time. These findings support the BF as an effective intervention, though further research is needed on extended outcomes. Conclusions: BF is an effective surgical intervention for VPI, significantly improving hypernasality, speech intelligibility, and audible nasal air emissions. While benefits are evident across diverse populations, long-term outcomes and secondary features, such as nasal turbulence, show variability, emphasizing the need for individualized approaches and continued follow-up. This technique offers a reliable option for functional and speech rehabilitation, though further research is needed to optimize its long-term efficacy and broader outcomes. Full article

Efficiently mapping hourly air quality at a fine scale (25 m) remains a computational challenge. This difficulty is heightened when aiming to accurately capture industrial plumes and time-varying traffic emissions. This paper presents a method for generating hourly pollutant concentration maps across an entire region for operational applications. Our approach assumes that concentration maps can be decomposed into three components: traffic concentrations, industrial concentrations and a residual “background” concentrations component. The background concentration is estimated using established fine-scale mapping methods involving ADMS-Urban dispersion simulations. Meanwhile, the traffic and industrial layers are derived using a KNN-based approach applied to a sample of hourly ADMS-Urban simulations. This method enhances the representation of industrial plumes and the temporal variability in traffic emissions while maintaining computational efficiency, making it suitable for the operational production of hourly air quality maps in the Hauts-de-France region (France). Full article