Air Change Research Articles

Performance Evaluation of Low Thermal Bridging Drywall System with Separating Clips for C-Studs

Drywall systems comprising gypsum boards and steel C-studs are widely used due to their lightweight structure, rapid construction, and ease of installation. These systems must meet the required thermal insulation performance for their specific applications. However, metal C-studs penetrate the insulation layer at intervals, leading to additional heat loss, reduced thermal insulation performance, and lower indoor surface temperatures, which can result in condensation and mold growth. To address these issues, this study proposes a drywall system with low thermal bridging studs made up of two small-sized studs and four or five separating clips made of reinforced plastic. These clips separate the studs to minimize heat transfer through metal elements, maintain structural stability despite the spacing between them, and facilitate easy assembly. The results from mock-up tests showed that the proposed system’s thermal transmittance was 0.370 W/m2K, which is 28.8% lower than the 0.52 W/m2K observed with conventional C-studs. The proposed drywall system also met Korean regulations for acoustic insulation level 3 and the 2 h fire resistance criteria, similar to existing drywall systems with conventional C-studs. Moreover, the maximum and residual displacements were within an acceptable range for a horizontal load of 3000 N applied vertically to the non-load-bearing wall. Building energy analysis indicated that using the proposed drywall adjacent to unconditioned spaces could reduce the annual heating and cooling load by 2.5–3.0%, despite a 1.5–1.9% increase in the annual cooling load. The annual heating load decreased by 4.8–5.9% under infiltration rates of 0.5 to 1.5 air changes per hour for adjacent unconditioned spaces, making this drywall system’s improved insulation quality crucial for achieving heating-dominant zero-energy buildings.

Analysis and performance prediction of a building integrated photovoltaic thermal system with and without phase change material

Increasing energy demand in buildings in the last decade has led to more efficient usage of renewable energy. Building integrated photovoltaic/thermal systems is one of the effective ways of reducing energy consumption in buildings by providing heating, cooling, ventilation, hot water, and air. The enhancement of photovoltaic cell temperature reduces the electrical efficiency of photovoltaic panel systems. In this regard, the effects of cooling with air and phase change material layer are investigated in this study. The simulation of BIPV/T, PV, and heat pump was done in TRNSYS. As the main novelty of recent simulation, for the calculations of phase change material layer, MATLAB coupled with the TRNSYS, and Python software was used for the prediction process under the weather conditions of Sharurah, Saudi Arabia for 2022. Also, the performance of a building integrated photovoltaic/thermal system with a phase change material layer is predicted for 2024 and 2025 by the Random Forest machine learning method. The R squared, Root Mean Squared Error, and Mean Absolute Error are utilized for checking the accuracy of the model. Also, for more certainty, a validation was done on the simulated results of TRNSYS and the results showed high conformity of data. The simulated data for the first six months of 2022 showed that the maximum cooling effect happened in June with 25.47 °C and a 37.87 % reduction in photovoltaic cell temperature. Also, the best electrical efficiency improvement was 1.26 % while the thermal efficiency ranged from 29.65 % to 59.40 %, respectively. The predicted data was confirmed by R2, RMSE, and MAE equal to 96.64 %, 0.06 and 0.04. According to the simulation and predictions done, the annual electrical production of the building is achieved. The results indicate that, for the simulated system, about 29.7 %, 29.8 %, and 29.6 % of total energy utilization could be supplied by BIPV/T cooled with phase change material in 2022, 2024, and 2025, respectively.

Assessment of airborne transmitted infection risk in classrooms using computational fluid dynamics and machine learning-based surrogate modeling

In recent years, the assessment of airborne transmitted infection risk has been extensively performed using Computational Fluid Dynamics (CFD) simulations, especially in response to the COVID-19 pandemic. Nevertheless, the high computational demands and time-intensive nature of CFD simulations highlight the need for fast or real-time infection risk predictions. This capability is crucial for swift decision-making in dynamic environments where timely health interventions are critical. This paper presents a thorough analysis of airborne infection risks in classroom environments based on CFD simulations to understand key factors such as ventilation strategies, air change rates, occupant arrangements, source locations, and particle sizes. This study also employs data-driven supervised learning methods—specifically, Long Short-Term Memory (LSTM) and Artificial Neural Networks (ANN)—to generate surrogate models for predicting airborne infection risk. Key findings reveal that different ventilation strategies significantly affect airborne infection risk, reducing it by 49 %–77 %. Moreover, the conventional Wells-Riley model was identified as lacking in its ability to accurately predict local infection risks. The study further challenges the assumption that higher air change rates are universally beneficial, considering that occupants seated in the back rows of a classroom experienced up to a 166 % increased risk, despite elevating air change rates from 1.1 h−1 to 11 h−1. These results suggest that physical distancing alone may be insufficient and highlight the importance of considering other factors such as occupant arrangements. Regarding the model performance, the ANN-based surrogate model demonstrated varying prediction accuracy. For inhalable particle concentration predictions for susceptible occupants, R2 values ranged from 0.31 to 0.65 with CVRMSE values between 100 % and 180 %. In contrast, the model achieved an R2 of 0.79 and a CVRMSE of 34 % for infectors. The insights and methodologies from this study can inform HVAC system design and operation strategies to better mitigate infectious disease transmission in densely occupied indoor environments.

An effective and efficient approach for smoke control in underground parking garages

Underground parking garages are enclosed spaces not directly exposed to the exterior. A smoke control system is typically required to facilitate occupants’ safe evacuation/relocation and assist in firefighting/rescue. Currently, there is a lack of guidelines for designing such systems in primary codes/standards. Only a limited number of local authorities have developed amendments to address this issue. These amendments either rely on outdated approaches, such as air change method, or simply repurpose carbon monoxide ventilation systems for smoke control without conducting additional engineering analysis and providing justification. The intent of this study is to examine the adopted approaches and explore an effective and efficient approach for garage smoke control. According to the study’s findings, it is discovered that garage floor height significantly impacts the performance of smoke control system. Additionally, structural components (beams) also influence the performance of smoke control system. Moreover, this study derives a linear equation to ascertain available safe egress time (ASET) when utilizing the carbon monoxide ventilation system or typical air change methods. Taking cost into consideration, the study concludes that for effective and cost-efficient smoke control in large underground garages, employing a carbon monoxide ventilation system is preferable to the traditional or equivalent air change method.

Cardiac Output Directly Influences Intracardiac Air After Venous Air Embolism: An Echocardiographic Model Comparing Position Change on Intracardiac Air Bubble Clearance.

Venous air embolism (VAE) can cause significant morbidity and mortality. Prevention and management of VAE include cessation of air entrainment, positioning changes, and hemodynamic support. The degree to which position change and cardiac output (CO) moderate resolution of intracardiac air has not been rigorously studied using contemporary transesophageal echocardiography (TEE). This observational cohort-type study aimed to identify the effect of supine vs sitting positioning on the movement and resolution of intracardiac air. In 20 patients undergoing seated neurosurgery, central venous air aspiration catheters were placed through the median basilic vein. TEE was used to estimate the time required for clearance of agitated microbubbles from the right atrium and ventricle in both the supine and sitting position. Estimates of CO were also obtained echocardiographically in each position. Average clearance time was faster in the sitting vs the supine position with no significant difference in CO. A negative correlation between CO and right atrial clearance time across all patients was demonstrated with a Pearson coefficient of -0.4 (95% CI -0.07, -0.65) with P = .02. During VAE, both patient position and CO can significantly affect how bubbles move through intracardiac chambers. However, augmenting CO during VAE may be clinically more feasible, efficient, and productive than changing positioning-especially during crises unless the changing in position is intended to halt the entrainment of air. Further TEE studies of intravascular air movement affected by other position changes (lateral, reverse Trendelenburg) and vasopressors should be considered.

“Don’t miss the globe” – Study of diagnostic accuracy of computed tomography in detecting open globe injury

Abstract: PURPOSE: The purpose is to determine the computed tomography (CT) characteristics of open globe injury and establish the relative accuracy and reliability of various features on CT. Second, to assess the significance of a difference in the anterior chamber depths (ACDs) on CT in cases of open globe injury. METHODS: The diagnostic database of our radiology department was retrospectively reviewed to obtain details of patients with a history of blunt or penetrating injury to the orbit between September 2018 and March 2021. A total of 190 patients (144 males and 46 females) were included. A radiologist analyzed the CT scans without prior knowledge of ophthalmologic findings or surgical outcomes. Operative and ophthalmic examination findings were considered the gold standard for comparison. RESULTS: Out of 190 injured globes, the final clinical diagnosis confirmed 54 (28.4%) open globe injuries and 136 (71.5%) closed globe injuries. Between the two groups, intraocular hemorrhage, lens dislocation, lens injury or absence, intraocular foreign body, intraocular air, wall/contour defect, and ACD change were considered statistically significant (P < 0.05). The average sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of CT in diagnosing open globe injury were 71.3%, 98.5%, 83.6%, 95.75%, and 94.9%, respectively. CONCLUSION: Globe contour deformity or defect, intraocular hemorrhage, and a change in ACD were the three most predictive signs of open globe injury. CT is of valuable help in a multi-trauma setting and in an uncooperative patient for ophthalmological examination to draw attention to globe injury. However, CT examination alone is insufficient in detecting all cases of open globe injury. There is a need for a more collaborative approach among emergency physicians, ophthalmologists, and radiologists.

Simulation and design of a solar chimney integrated with phase change material layer for building ventilation

The development of modern life requires new energy sources, and one of this energy is renewable solar energy uses in solar chimney for natural ventilation, but at the present time it is not greatly invested, taking into account the weather conditions of the region and the physical characteristics of solar radiation and air in the area in which the study will be conducted. The current study was carried out in Basrah city- Iraq, at longitude 47.749° and latitude 30.568°, where the solar chimney was facing south. The investigation was conducted using both theoretical and experimental studied. In the theoretical study, the solar chimney with the room in the presence and absence of PCM was simulated numerically using the finite volume method using the soft package ANSYS-Fluent/2021/R2. The effect of different tilt angles (α = 30°, 45°, and 60°), solar chimney air gap (gab = 10 cm, 15 cm, and 20 cm), and PCM basin thickness (tPCM = 3 cm, 4 cm, and 5 cm) were investigated. The results were presented in the form of contours of the distribution of streamlines, velocity, temperature, and liquid fraction of the solar chimney with the room, rate of temperature of the absorber plate with time and the rate of temperature of the PCM (TPCM) with time, rate of air change per hour (ACH). As for the experimental side, the device was built, and the intensity of solar radiation was studied for several days on 30 Sep. and 15 Oct. 2023, the temperature distribution rate of the absorbent plate over time, the PCM temperature rate, and the air change per hour (ACH). The theoretical results were compared with the experimental results, where there was good agreement, and the theoretical comparison was also made with several researchers. Significant results showed that the optimal ratio of the air gap width of the solar chimney is 15 cm, the inclination angle of the solar chimney α = 30°, and the thickness of the PCM basin (tPCM = 4 cm) to obtain the maximum ventilation rate. The thickness of the PCM basin = 4 cm gives the largest liquid fraction along time and maximum average temperature of the absorber plate. On the experimental, it was found that PCM convert into the liquid phase after its melting point, which is 340 K, after 12 noon, and the highest value of ACH reached 37 on September 30/2023 at midday.

VOC emission rates from an indoor surface using a flux chamber and PTR-MS

Arising from the Chemical Assessment of Surfaces and Air (CASA) 2022 study at the National Institute of Standards and Technology (NIST) Net-Zero Energy Residential Test Facility (NZERTF), this paper presents the first evaluation of indoor surface emissions to a house measured with a surface flux chamber coupled to an online, non-targeted volatile organic compound (VOC) mass spectrometric detection. These surface emissions are compared to those assessed using ambient, whole house indoor VOC measurements and the outdoor air change rate. Chamber emission rates varied by almost four orders of magnitude across 35 quantified VOCs. The whole house emissions measured by campaign-long ambient measurements and the flux chamber emissions (when scaled to the painted surface area of the house) are similar, with an average ratio between the two of 1.3 ± 1.0. The general agreement between these two approaches indicates that the flux chamber was not solely measuring primary emissions from building materials located below the chamber. Rather, the results suggest that over the 12-year house lifetime, VOCs have been widely distributed around the house, migrating from their primary sources to secondary surface reservoirs. With the house in a quasi-steady state, the thermodynamic activities (i.e., the vapor pressures) of the VOCs within the different reservoirs become similar. Emissions of aromatics and monoterpenes have declined since the house was built, whereas aldehyde emissions have remained relatively constant.

Experimental and numerical investigation of arch concrete slabs subjected to underwater contact explosions with the inner arch side facing air

Arch structures with their inner arch side exposed to air and outer arch side exposed to water are often encountered in practical projects, and these engineering structures may be subjected to various explosive attacks during operation. This paper investigates the damage mechanism and dynamic response of arch concrete slabs with the inner arch side facing air against underwater contact explosions (UWCEs). The explosion tests of the arch concrete slab with the inner arch side facing air were carried out. The accuracy and applicability of the numerical model were verified by comparing with the explosion results. After that, the failure evolution and energy transition of the arch concrete slab with the inner arch side facing air were studied. The effects of different explosion masses, explosion distances, and reinforcement schemes on the antiknock performance of arch concrete slabs are further explored. The results show that as the explosive mass of UWCEs increases, the damage mode of the arch concrete slab with the inner arch side facing air changes from cracking along the longitudinal direction and local failure to spalling on the inner arch side and fragmentation of the contact specimens. The existence of curvature of the arch slab will cause the damage of the arch slab to intensify. The failure mode of the arch concrete slab changes from local failure to slight failure with cracks as the explosion distance increases. Increasing the longitudinal steel bars on the outer arch side can effectively inhibit the generation and development of cracks.

Natural ventilation in large spaces: CFD simplified model validated with full-scale experimental data of Roman Baths

This study addresses the escalating need for energy-efficient and well-ventilated buildings by examining natural ventilation in large spaces. Validation of a CFD model was pursued through in-site experiments at the Roman Baths Museum in Chaves, Portugal. A sensitivity analysis aimed to determine the optimal number of monitoring points for model validation, crucial for establishing procedures in large-volume settings. Findings emphasized the feasibility of using a minimal number of monitored points, notably with a 3 × 3 test point arrangement, showcasing consistent temperature variations with low relative errors (0.50 %–1.75 %). Furthermore, the validated model assessed ventilation performance under diverse operational conditions, revealing slight enhancements in experimental settings, including an increase in air change rate (2.4 vs. 2.2 ACH) and a decrease in buoyancy dominance (Richardson number 197.3 vs. 241.3) compared to design conditions. Quantitative analysis highlighted similar temperature and velocity trends, with greater stratification in experimental conditions (temperature ratios 0.12 to 0.36 vs. 0.10 to 0.32). Qualitative assessments align with the quantitative analysis and enable the identification of stagnation zones and airflow distribution patterns. These findings affirm the methods' reliability in analysing ventilation in large spaces naturally ventilated, validating the model across diverse contexts, despite fewer data points.

CFD modeling of reactive species air cleaner applications in a classroom

Due to increasing concerns related to airborne virus spread indoors, more reactive species air cleaners are being utilized in classrooms. Reactive species generated by air cleaners decompose airborne pathogens chemically, decreasing the risk of infection. Due to the high reactivity of these oxidants, reactive species may be distributed nonuniformly in indoor environments, as are viral aerosols emitted by infectors. Heterogeneous distributions of reactive species may cause spatially non-uniform removal rates of viral aerosols. However, there is little information regarding spatial distributions of either reactive species or viral aerosols in ventilated classrooms. Thus, the objective of this study was to investigate spatial distributions of reactive species and infectious aerosols and to examine how operating conditions of air cleaners affect viral aerosol removal rates. A CFD model simulated the operation of a reactive species air cleaner generating hydrogen peroxide (H2O2) in a mechanically ventilated 237 m3 classroom with nine occupants. The reactive species air cleaner showed a 3–20 times higher equivalent air change rate to a HEPA filter air cleaner with the same inlet and outlet flows. During the operation of reactive species air cleaners, elevated viral aerosol concentration was confined to regions near infectors. This was due to the high reactivity of reactive species, decreasing the infection probability of receptors from 3.2 % to 0.1 % with a 1-hour exposure time. As the room average concentration of reactive species increased from 15.6 to 50.4 ppb, both below the US Occupational Safety and Health Administration (OSHA) Permissible Exposure Limit (PEL) of 1000 ppb, the room average infection probability decreased from 0.3 % to 0.1 %. Due to the residence times of reactive species, the location of reactive species air cleaners affected the inactivation rate of viral aerosol, resulting in a 24 % variation of concentration difference of infectious aerosol with air cleaner locations.

Seasonal indoor air quality, self-reported health and comfort amongst tenants living at Danish multi-family social housing sites

Studies have identified seasonal differences between the indoor environment and residents’ comfort, as well as an association between indoor air quality (IAQ) and residents’ overall health. Furthermore, measured IAQ is not always aligned with perceived IAQ. The HOME-Health study is a cross-sectional study with seasonal measurements of IAQ amongst residents living in social housing. The aim is to describe and analyse measured and perceived IAQ, and residents’ health symptoms. We found a lower relative humidity, temperature (TP) and air change level (h−1) level, and a higher carbon dioxide (CO2) level during winter compared to summer. In general, higher IAQ levels were measured in apartments with increased crowdedness. The inability to be able to create cross ventilation increased TP, and a larger number of rooms decreased TP. Overall, there was no clear alignment between measured and perceived IAQ, but we found a trend that higher CO2-levels led to a perception of poor IAQ especially during summer. Overall, draught and thermal discomfort were the most common complaints. Self-reported humidity was increased during winter and was associated with nasal and respiratory symptoms, whereas self-reported humidity during summer was associated with fatigue and dermal symptoms. Findings show challenges with IAQ in Danish social housing that are associated with negative health issues.

Optimum configuration of internal walls in intermittently conditioned rooms with different ventilation-behavior during off-periods and air conditioner operation durations

Investigations focus on optimizing insulation placement and thickness within internal walls of rooms equipped with intermittently operated air conditioners (AC), specifically targeting buildings located in China's Hot Summer and Cold Winter region. To achieve this objective, cooling and heating transmission loads for internal walls with varying insulation thicknesses, both internally and externally insulated, are calculated using EnergyPlus. Calculations are repeated across different air change rate (ACH) during AC off-periods and for varying AC operation durations. Subsequently, these transmission loads facilitate the determination of the optimal insulation position and thickness. The findings demonstrate that the internal walls with inside insulation (Wall-2) achieves an energy-saving rate of approximately 16–20 % during the cooling season and 30–60 % throughout the heating season when compared to that with outside insulation (Wall-1). Moreover, Wall-2's energy-saving advantage over Wall-1 is further accentuated with heightened ACH during off-periods and reduced durations of AC operation. Additionally, the optimal insulation thickness for Wall-2 was determined to be 0.06 m, 0.08 m, and 0.098 m for AC operation durations of 4 h, 7 h, and 10 h, respectively, with ACH having no impact on this optimal thickness. Life cycle savings varied between 254.56 and 552.31 ¥/m2/year, while payback periods varied between 1.76 and 2.33 years. These two indexes are both influenced by AC operation durations and ACH. Finally, the total energy consumption for cooling and heating is reduced by 40–50 %, when the internal wall is insulated to the optimal thickness internally.

Variations of dissolved trace elements in precipitation and stream water in Japanese forest area: additional evidence of changing air pollution in the region

Trace elements released into the atmosphere by human activities, such as fossil fuel combustion, flow into forest ecosystems via wet and dry deposition and can flow out via mountainous stream water. The Kajikawa catchment site in Niigata Prefecture, located on the Sea of Japan side in central Japan, suffers from large amounts of acidic substance deposition due to its geographical conditions and meteorological seasonality and is affected by transboundary air pollution originating from the Asian continent due to northwesterly seasonal winds in winter. This study determined the concentrations of trace elements dissolved in precipitation and stream water to comprehensively evaluate the effects of transboundary air pollution on forest ecosystems. The results showed that the concentrations of trace elements and major inorganic ions in precipitation tended to be high in winter and low in summer. The fluxes of many trace elements also increased in winter, reflecting high precipitation amount. Except for Sr, the enrichment factors of the highly enriched trace elements did not show clear seasonality. Therefore, they were continuously influenced by anthropogenic activities. Furthermore, the stable Pb isotope ratio changed significantly during the observation period; however, this was not explained by seasonal changes. This study revealed that trace elements are transported to the Sea of Japan side in central Japan, especially in winter; however, their quantity and content change in response to changes in local and transboundary air pollution.Graphical

Uneven changes in air and crown temperatures associated with snowpack changes affect the phenology of overwintering cereals

Time series analysis of overwintering cereals in snowy areas has revealed several phenological patterns associated with climate changes in winter. Herein, to investigate the recent effect of climatic variations on overwintering cereals, we investigated the phenology over multiple decades at three snowy region sites with an air temperature (Tair) increase trend of 0.48–1.09 °C/decade. Our findings were as follows: heading trends differed within the same cultivar at different sites; phenology was promoted with increasing temperatures in cooler regions and decreasing snow duration in regions with heavy snow; crown temperature (Tcrown) was a more direct determinant than Tair in phenology estimation model in regions with heavy snow. A thermal gap of more than a few degrees Celsius between Tair and Tcrown, owing to the insulation effect of snowpack, affected the phenology of overwintering cereals. A shorter snow cover period promoted phenology in locations with temperatures >0 °C. Subsequently, we found that when the thermal gap was >0 °C of the growing temperature range, Tcrown directly helped determine the phenology of overwintering cereals, and irrespective of the warming trend, the periodic inflow of cold air into the northern mid-latitudes of the Northern Hemisphere and associated snow cover changes dominated Tcrown, resulting in annual phenological anomalies with a range of fluctuations of approximately 1 month. The trend of increasing Tair during spring in northern Japan is consistent with the global trend, with a pronounced trend of advancing phenology reaching >4 days/decade in a typical cooler location experiencing snowmelt in March.

Use of wearable ventilation for reducing the infection risk of healthcare workers in isolation wards: A numerical study

This study investigates the protective effectiveness of a novel head-mounted air supply (HAS) system on healthcare workers (HCWs) in COVID-19 isolation wards. The study employs computational fluid dynamics (CFD) to explore the effectiveness of the HAS and the infection probability for HCWs during constant exhaling and coughing of patients. It also studies the effect of air changes per hour (ACH) and exhaust outlet locations in the isolation ward on the infection probability of the HCW. Additionally, the effectiveness between the HAS and various types of common masks is compared. Results indicate that when the flow rate of the HAS reaches 10 L/s with supplying clean air, the infection probability of the HCW can be reduced from approximately 30 % without protection to below 0.18 %. Patients' coughing increases the infection probability of the HCW by approximately tenfold within a short period, and wearing the HAS can effectively reduce the effect of patients’ coughing on the HCW. When ACH increases, the infection probability of the HCW decreases. Wearing the HAS can mitigate the effects of changes in ACH, with an infection probability below 0.18 % at 9 ACH or above. Ceiling-level exhausts are more effective than floor-level exhausts in removing pollutants from the ward. Under experimental settings, HAS with suitable parameters may be more effective than commonly used masks in terms of reducing the infection probability of the wearer. These findings provide valuable references for the application of wearable ventilations in hospital environments.

Effect of frequent clearcutting on some soil properties, temperatures, and herbaceous vegetation and the potential of their recovery in a short time.

Harvesting or degradation of forest ecosystems directly affects the microclimate, causing changes in air and soil temperatures and soil moisture in the forestlands. The objectives of this study were to investigate the effect of frequent clearcutting of forest cover on some selected soil properties, ambient and soil temperatures, soil moisture, and herbaceous vegetation cover and determine their recovery in a short period in the area subject to frequent clearcutting under the powerline corridors (PLCs). The study was conducted in the research forest of Istanbul University-Cerrahpaşa, Faculty of Forestry. The treatment plots were selected from the clearcut area, and control plots were selected from an untouched oak-hornbeam forestland. Soil temperature and moisture and maximum and minimum ambient temperatures were measured in the treatment and control plots between 2020 and 2021 and topsoil sampled between 2019 and 2021. Data were analyzed using analysis of variance (ANOVA) to test the effects of clearcutting on some selected soil properties in the short term after cutting. Clearcutting caused a significant increase in soil bulk density (BD) and a decrease in the soil total porosity (TP), soil hydraulic conductivity (HC), and saturation capacity (SC). Forest cover removal significantly decreased the soil organic matter (SOM) content by 3%, increased average soil temperature by 2.1°C, and the difference between maximum and minimum temperatures by 8.8°C. Additionally, clearcutting reduced the average soil moisture from 36 to 35%. The findings revealed that clearcutting negatively affected some hydro-physical soil properties and soil microclimate conditions that may not recover to their previous states within the next few years.

Influence of Hydrological and Climatic Changes on Tree Growth in Narew National Park, NE Poland, over the Past 50 Years

Over the last 50 years, groundwater levels have been decreasing and air temperatures have been increasing in Poland. Maintaining this trend may make it impossible to maintain hydrogenic habitats in good condition. Reactions to ongoing climate change recorded in tree rings may be a good indicator describing the degree of this threat. The aim of this study was to determine the influence of climatic and hydrological changes on the growth of scotch pine (Pinus sylvestris L.) and black alder (Alnus glutinosa (L.) Gaertn) in the Narew National Park over past 50 years. The research was based on tree increment cores extracted from 42 pine trees and 57 alder trees that were randomly selected and ranged in age from 25 to 88 years, as well as climatic and hydrological data. Standardised data (5-year index) were analysed by species, generation (Y—21–40 years, M—41–60, O—61–90), and decade using correlation analysis. The results of the study show that pine responded more strongly to changes in air temperature and changes in precipitation totals, while alder growth was more strongly related to fluctuations in the water level of the Narew River and changes in precipitation totals. Our research showed that differences in response to environmental factors also occur between tree generations. The decrease in the water level of the Narew River that occurred over the last 50 years did not adversely affect the condition of the trees. Analysis of DBH growth rates showed that the younger generations (Y, M) grow faster than the older generation (O). This is positive news for managers of commercial and protected forests, but accelerated tree growth may be associated with specific consequences, such as increased wind damage as a result of reduced wood density or reduced sensitivity of trees to climate and hydrological changes.

Ambient Air Pollution and Depressed Mood in the National Longitudinal Study of Adolescent to Adult Health (Add Health) Wave IV.

Depression is a major contributor to the global burden of disease. There is limited understanding of how environmental exposures may contribute to depression etiology. We used Wave IV of the National Longitudinal Study of Adolescent to Adult Health (Add Health) to examine associations between low-level ambient air pollution exposure and depressed mood in a generally healthy population of over 10,000 24-32 year olds. Annual mean PM2.5 levels in the 2008-2009 study were close to the current U.S. standard. In fully adjusted quasi-binomial logistic regression models, there were no meaningful associations between IQR increases in air pollutant and change in depressed mood status regardless of specific pollutant or moving average lags. In interaction effects models, an IQR increase in lag day 0-30 PM2.5 resulted in 1.20 (95% CI, 1.02-1.41) times higher likelihood of having depressed mood, but only for persons with chronic lung disease (interaction P=0.04); the association was null for participants without chronic lung disease (OR 0.98, 95% CI, 0.91, 1.05). Our findings suggest that among persons with a lifetime history of chronic lung disease, greater exposure to even low-level PM2.5, PM10, and sulfate may be associated with modest increases in the likelihood of having depressed mood.

Impacts of Climatic Changes and Air Pollution on Public health and Environment

Air pollution is an emerging highlight in developing countries in changing climate, it is considered one of the greatest concerns of public, individual, and environmental health. The rate of mortality and morbidity seems to increase due to air contamination. There are many types of air pollutants, some of the major air pollutants are particulate matter (PM), carbon monoxide (CO), nitrogen oxides (NOx), sulfur oxides (SOx), and lead (Pb). PM are minute suspended particles that can inhaled while breathing and cause cardiovascular and respiratory disorders, nervous system diseases, and cancer. High levels of CO inhalation cause poisoning in humans. Nitrogen oxides are latent greenhouse gases with high global warming potential and deplete the ozone layer. SOx causes intoxication when absorbed by the human body. When lead is absorbed by the human body by inhalation it may cause toxicity, chronic obstructive pulmonary disease, asthma, and lung cancer. Thereafter air pollution and changing climate lead to the spread of many infectious diseases. Hence, the way to manage this problem of air pollution is to make the public aware of impacts and management practices. The scientific and medical experts should conduct multidisciplinary research at the national and international level to sort out this problem in a sustainable way.