High Humidity Levels Research Articles

Transmission of COVID-19 in Cities with Weather Conditions of High Air Humidity: Lessons Learned from Turkish Black Sea Region to Face Next Pandemic Crisis

The goal of this study is to analyze associations between COVID-19 transmission and meteorological indicators in cities of the Black Sea region of Turkey, located specifically in the dampest area, with excess rainfall and recurring fog. In particular, the working hypothesis is that the widespread transmission of new coronavirus SARS-CoV-2 (leading to the airborne disease COVID-19) in cities can be explained by specific weather conditions, namely high levels of air humidity. Statistical evidence here does not seem, in general, to support the hypothesis that the accelerated transmission of COVID-19 in the studied cities can be explained by high levels of humidity because different meteorological, environmental, demographic, and socioeconomic factors also plays a critical role in the disease transmission dynamics of the investigated region. The main implications of our findings here are that the demographic structure of the population, climate indicators, organization of the health system, and environmental factors (e.g., air pollution, etc.) should be considered through a systemic approach when designing effective national and regional pandemic plans directed to implement health policies for facing new variants of COVID-19 and/or new airborne diseases, in order to reduce their negative effects on health, social and economic systems.

Vertical distribution of VOCs in the boundary layer of the Lhasa valley and its impact on ozone pollution

To investigate the vertical distribution of volatile organic compounds (VOCs) concentrations in the Lhasa valley region, an intensive measurement campaign was first conducted in summer using a tethered balloon. The results showed that the average concentration of surface VOCs was 49.1 ± 30.1 ppbv, alkanes and aromatics were the main components. Notably, a very large discrepancy in VOCs was obtained between the wet (71.6 ± 25.9 ppbv) and dry (25.6 ± 8.0 ppbv) episodes, which was attributed to the atmospheric stability and diffusion capacity. Moreover, the total VOC (TVOCs) concentration declined under fluctuations, but it rapidly increased with height in the afternoon during the wet episode (2.50 ppbv/100 m, R2 = 0.47). According to the PMF results, combustion was the dominant emission source, additionally, the contribution of solvent coating in the wet episode and the background in the dry episode increased with height. Moreover, the O3 concentration increased with height, and the decrease in LNOx-OH could effectively prevent the occurrence of high O3 values. This study indicated that low wind speeds and high humidity levels highly likely cause the accumulation of atmospheric VOCs under static and stable conditions, while the control of high O3 concentrations must still greatly consider summertime NOx emissions in Lhasa.

Enhancing Gas Turbine Power Plant Performance in Tropical Climates by Using Inlet Air Cooling with Desiccant Dehumidification and Evaporative Cooling

Abstract Gas turbine power plants play a crucial role in meeting the growing demand for electrical energy. However, their performance can be hindered by high ambient temperatures and humidity levels in tropical climates, leading to a drop in power output. This study investigates the potential benefits of using inlet air cooling with desiccant dehumidification and evaporative cooling to improve the performance of gas turbine power plants in tropical regions. The results show that this inlet air cooling method, integrating evaporative cooling, desiccant wheel, and Maisotsenko cooler, is a viable alternative for mitigating the performance decrease of gas turbines in hot tropical conditions. Furthermore, the compressor inlet temperature can be reduced on average by 11.5 °C by using turbine exhaust gases to heat the regeneration air utilized in the desiccant wheel for dehumidification. Additionally, the power requirement of the inlet air cooling system amounts to around 0.9 MW compared with an improvement of more than 2 MW in power output at peak temperature. Further research is needed to understand and quantify other benefits related to inlet air cooling, such as reducing emissions of harmful pollutants and operating at higher turbine inlet temperatures.

Analytical Investigation of Two Socialist Realism Portraits Exposed to High Levels of Humidity. Case Studies from the Historical Museum of Bosnia and Herzegovina

This paper describes the combined use of several analytical methods to characterise the painting technology used in two socialist realism portraits of national heroes from World War II that are now housed in the Historical Museum of Bosnia and Herzegovina. Inspection under UV light has shown that there was no previous retouching or overpainting on either painting. Microchemical tests identified the type of canvas. The radiograms indicated whether pigments with lower or higher atomic masses were used and how well the ground was rubbed among the threads of the canvas. A better penetration of the ground into the canvas and layers of oil dye that were applied to both sides of Painting 1 contributed to its better protection against high humidity. TLC revealed the type of ground on both paintings as a classic chalk-glue ground. The high humidity was responsible for the occurrence of metal soaps on Painting 2, which were confirmed by FTIR. The XRF analysis was used to describe the pigment palette, trace the causes of existing damages, and facilitate retouching. The results of this integrated diagnostic approach were used to optimise the conservation and better understand the features and techniques used in the creation of Bosnian socialistic artwork.

Harnessing climate variables for predicting PV power output: A backpropagation neural network analysis in a subtropical climate region

This study examines the influence of weather conditions on the electricity production of photovoltaic (PV) panels in the Conghua district, a region in Southern China distinguished by its subtropical mountainous climate. The area's high humidity levels, high temperatures, and substantial rainfall often lead to predominantly cloudy skies, which alter solar irradiation patterns as a result. Utilizing the EnergyPlus simulation tool, the power generation of PV panels on rooftop application was simulated. A structured classification method is adopted to sort out weather conditions into categories of sunny, cloudy, and rainy. Through examining the influence of these varied weather scenarios on power generation, unique factors affecting electricity outputs are identified. As a result, this study illuminates the relationships between potential weather variables and PV power generation across each weather category. Subsequently, a back propagation neural network (BPNN) model is utilized to explore the relationship between weather categories and PV generation. The high coefficient of determination value (R2 > 0.95) from the comparison of simulated and predicted PV generation validates the model accuracy. This research enables the development of updated dataset and enriches the prediction of rooftop PV power generation. It equips designers and owners with a reliable, user-friendly, and real-time tool for PV power generation forecasting, and provides a working platform for PV performance evaluation during the design phase of PV projects. The insights derived from the BPNN model could guide the optimal design and implementation of PV systems in similar climates. Furthermore, these findings advance sustainable energy solutions in regions affected by complex weather patterns.

Room Temperature and Humidity Control System Using Arduino and Blynk

The temperature and humidity of a room can be a problem that affects the comfort and health of its occupants. Issues such as excessively high or low temperatures and humidity levels can make it difficult for people to sleep and cause discomfort. Various solutions can be implemented, such as using IoT-based temperature and humidity monitoring systems, platform Blynk to optimize temperature and humidity control, and designing control circuits using actuators such as fans with relays. This control system uses the Blynk application to monitor and turn on and off the actuators in this study using a fan. Arduino Wemos D1 as the main processor, and for sensors, DHT22. Test method by placing the system in a room with an area of 3 x 3 m. The results of the test with the fastest average time were in the morning with a time of 10 minutes, 52 seconds. The longest average time was obtained during the day, with a test time of 14 minutes, 38 seconds. The difference in error between the system and the comparison is the highest at a temperature of 2.71% and at a humidity of 33.5%.

Geometric Analysis of Free and Accessible Volume in Atmospheric Nanoparticles.

Computer-generated atomistic microstructures of atmospheric nanoparticles are geometrically analyzed using Delaunay tessellation followed by Monte Carlo integration to compute their free and accessible volume. The nanoparticles studied consist of cis-pinonic acid (a biogenic organic aerosol component), inorganic ions (sulfate and ammonium), and water. Results are presented for the free or unoccupied volume in different domains of the nanoparticles and its dependence on relative humidity and organic content. We also compute the accessible volume to small penetrants such as water molecules. Most of the free volume or volume accessible to a penetrant as large as a water molecule is located in the domains occupied by organics. In contrast, regions dominated by inorganics do not have any cavities with sizes larger than 1 Å. Solid inorganic domains inside the particle are practically impermeable to any small molecule, thereby offering practically infinite resistance to diffusion. A guest molecule can find diffusive channels to wander around within the nanoparticle only through the aqueous and organic-rich domains. The largest pores are observed in nanoparticles with high levels of organic mass and low relative humidity. At high relative humidity, the presence of more water molecules reduces the empty space in the inner domains of the nanoparticle, since areas rich in organic molecules (which are the only ones where appreciable pores are found) are pushed to the outer area of the particle. This, however, should not be expected to affect the diffusive process as transport through the aqueous phase inside the particle will be, by default, fast due to its fluid-like nature.

Magnitude and origins of severe urban air contaminants in China during the COVID-19 lockdown: A comprehensive analysis

In an attempt to mitigate the spread of COVID-19, China implemented a series of strict lockdown measures in 2020, such as restricted road usage and reduced population flow, to safeguard public health. The resulting reduction in anthropogenic pollution emissions caused by the lockdown is informative for researchers seeking to explore the relationship between anthropogenic factors and atmospheric pollutants. Therefore, this study explored severe urban air pollutants and their driving factors before and during the lockdown in China. Across 367 Chinese cities, the implementation of strict lockdown measures led to substantial reductions of 22%–55% in major air pollutants, including PM10, PM2.5, NO2, SO2, and CO. However, O3 levels, which increased by approximately 58.0% during the lockdown, exhibited the opposite trend. This was potentially attributed to the consumption of NOx in the photooxidation process. To more thoroughly understand the relationship between air pollutants and their sources, four representative areas exhibiting considerable variations in air pollutant levels were selected: the Beijing–Tianjin–Hebei region (BTH), the Fenwei Plain (FWP), the Yangtze River Delta (YRD), and Southern central China (SCC). The land-use regression (LUR) model was employed for this purpose. Before the lockdown, various factors such as road-related emissions, rural residential areas, and grassland areas accounted for 13.2%–21.7% of PM2.5 and PM10 concentrations in the FWP region. Conversely, in BTH, YRD, and SCC, land-use-related sources such as plowland areas played an increasingly crucial role, contributing 12.9%–33.6% to PM concentrations. Moreover, human spatial activities and land-use types contributed up to 21.0%, 31.7%, and 20.8% to the elevated levels of SO2, NO2, and CO over the selected regions. During the lockdown, the LUR models revealed that changes in PM2.5 and PM10 concentrations were strongly associated with the influences of plowland and grassland. However, for NO2, SO2, and CO, anthropogenic sources such as trucks on the road, industrial emissions, and construction areas were identified as the main driving factors. Additionally, analysis using the generalized additive model revealed that before the lockdown, high humidity levels exceeding 50% were associated with increases in PM2.5 concentrations in the BTH and FWP regions. By contrast, during the lockdown, gas pollutants such as NO2 and SO2 emitted from livelihood-related activities had an effect on PM2.5 levels, contributing 10%–15% across all four regions. Overall, this study provides crucial evidence to inform the formulation of well-informed air quality strategies by considering key influencing factors in the future.

Stepwise percolation behavior induced by nano-interconnection in electrical conductivity of polymer composites

The electrical conductivity of polymer composites incorporating a continuous nanocarbon network is reported to be 1–2 logarithmic orders higher than that of the saturation region in a typical percolation model, indicating the existence of an undiscovered region. In this study, polymer composites with high filler content (∼50 vol%) are fabricated by powder mixing and in situ polymerization including sophisticated humidity control by promoting heat convection using an air fryer. Stepwise percolation behavior is observed, wherein the electrical conductivity of the composite with a high filler content exceeds that of the percolation plateau and further increases (3828% increase at 40 vol% multi-walled carbon nanotube (MWCNT) compared to 35 vol%), and the stepwise behavior is caused by the connected filler network (nano-interconnection). A novel stepwise percolation model that describes the behavior by considering both the tunneling resistance and the nano-interconnection is proposed. In addition, the stepwise percolation behavior induces high levels of electromagnetic interference shielding (236.36% increase at 50 vol% graphene nanoplatelet relative to 40 vol%) and humidity sensing (55.59% improvement at 40 vol% MWCNT compared to 35 vol%) properties. Therefore, derivation of the stepwise percolation behavior based on the nano-interconnection can be a new breakthrough in applications of conductive composites.

Failure Analysis of Galvanized Iron Pipe at Perumda Tirta Kanjuruhan

The most commonly used type of water pipe is iron pipe or commonly called Galvanized Iron pipe. The disadvantage of GI pipe is that it rusts easily. So it can result in degradation, decreased efficiency and construction, poor water quality, and higher maintenance costs. Water channeled through rusty pipes will pollute the water and adversely affect the health of those who consume it. This study aims to determine the factors causing failures of GI pipe in the distribution pipeline that have failed due to corrosion. The tested pipes is 1/2"ᴓ sized, 5-year-old corroded pipe whose distribution uses a gravity system and a pumping system. To support this analysis, operational data on fluid and environmental conditions around the pipeline are needed, observations on macro and micro structures, and hardness testing. The corrosion rate is calculated through the thickness loss method and the corrosion rate in the gravity system is 0.153 mm / year that higher than pipe in pumping system. Microstructure observations support the characterization of the material that this pipe is a mild steel, where this type of steel has a high Fe content so it is vulnerable to corrosion attacks. Rockwell hardness testing showed that the corrosion rate is directly proportional to the hardness value of the pipeline. The results of the analysis show that the environment around the pipe which has low soil resistivity and high humidity levels is the main factor in the occurrence of uniform corrosion of the pipe. The selection of inappropriate materials is also supportive as the cause of corrosion occurring.

Stable and Efficient Cu‐Based Zeolitic Octahedral Metal Oxides for Ethylene and Ethane Separation at High Temperature and Humidity

Zeolitic octahedral metal oxides based on vanadotungstate have shown great potential in gas separation. The microporosity of these materials is highly dependent on their structure and composition, allowing for precise tuning of their separation performance. In this study, zeolitic vanadotungstate is utilized for the separation of ethylene and ethane. The choice of cation is found to significantly impact the separation performance of the material. Specifically, the material with only Cu as the cation exhibits differentiated adsorption performance for ethylene and ethane, with high theoretical selectivity. Breakthrough experiments demonstrate that the Cu‐based material is able to effectively separate ethylene and ethane even at high temperature and humidity levels. Furthermore, the material exhibits excellent stability and is able to be reused without any loss in separation performance.

Photoresponsive Electrospun Fiber Meshes with Switchable Wettability for Effective Fog Water Harvesting in Variable Humidity Conditions.

The global water supply worsens yearly with climate change; therefore, the need for sustainable water resources is growing. One of them is fog water collectors with variable surface wettability, with multifunctional designs for utilization worldwide and to address regions with low humidity levels. Therefore, we created fiber meshes with a photoresponsive switchable surface. This study uses electrospun polyvinylidene fluoride (PVDF) meshes, whose wettability is controlled by adding TiO2. The fog water collection performance is studied at high and low humidity levels. With TiO2-PVDF, the electrospun mesh can be converted from hydrophobic to hydrophilic under UV irradiation and transformed back to a hydrophobic state with heat treatment. The switchable meshes were found to be more effective at water collection after UV irradiation at lower fog rates of 200 mL·h-1. The ability to switch between hydrophobic and hydrophilic properties as needed is highly desired in fog collection applications using electrospun meshes, as it can improve overall efficiency after UV irradiation.

Worldwide potential of emissive materials based radiative cooling technologies to mitigate urban overheating

Radiative cooling has gained significant attention in recent years for its passive heat evacuation capabilities. Numerous materials have been developed, but comparing their cooling effectiveness has proven challenging due to inconsistent experimental conditions. This study aims to bridge this gap by evaluating the heat evacuation potential of various radiative cooling materials under consistent climatic conditions.Using a validated heat transfer model, the performance of eleven materials was simulated in twenty-two Urban Overheating-affected cities. The assessment considered factors such as radiated heat losses, solar heat gains, and convective heat losses to gauge the cooling power of each material. The simulation assumed an active system where the materials were placed on a highly conductive, uninsulated surface, akin to having a fluid at a constant temperature beneath.The ability of materials to radiate heat and cool down depends on their optical properties. The findings suggest limited benefits in equatorial climates, with an average monthly total heat exchanged (MATHE) of −19.73 kWhm−2. Materials displayed consistent behavior throughout the year in climates with high relative humidity levels. Climates with elevated ambient temperatures derived the greatest advantages from strictly selective and highly reflective materials that emitted within the atmospheric window. Arid climates showed potential during transition times (MATHE -74.5 kWhm−2), while warm temperate climes benefited during summer months (MATHE -112.1 kWhm−2). In snow zone climates, the system could be utilized year-round for cooling-intensive scenarios, with a MATHE of −203.8 kWhm−2. This study evaluates radiative cooling materials' effectiveness in different climates, informing energy-efficient cooling applications.

Chemiresistive hydrogen sensors using a Pd-Ni nanocatalyst and a TiOx/PTFE humidity passivation

Hydrogen sensors are important not only in producing, storing, and handling hydrogen fuel but also in using hydrogen-powered devices. However, there are various challenges for practical use and commercialization of gas sensors such as (i) the cost reduction of materials for mass production, (ii) the sensitivity of the sensors towards a wide concentration range of analyte gas, and (iii) the stability of the sensors, especially in high humidity levels. For the first two objectives, our miniaturized resistive sensor based on a multilayered Pd-Ni nanocatalyst is developed. Our Pd-Ni sensors possessed excellent hydrogen sensitivity from 20 ppm to 100 % at room temperature. To solve the problem of humidity interference, polytetrafluoroethylene (PTFE) and titanate (TiOx) are used for passivating the sensors. With passivation, our sensors can operate well under high relative humidity conditions of up to 85 % RH at operating temperatures ≤ 80 °C. More importantly, the passivated Pd-Ni sensors are produced using dry methods (e-beam evaporation and sputtering), which are highly applicable in industrial-scale manufacturing.

Influence of humidity on activated carbon fabrics scheduled for use in high sensitivity radon detectors

The dependence of radon adsorption on the content of adsorbed water of activated carbon fabrics of ACC-5092-10 and ACC-5092-20 was studied experimentally. Specimens with different content of adsorbed water (from zero to saturation level) were coupled with alpha-track detector and exposed to reference 222Rn concentration. Both materials demonstrated different properties: Radon adsorption in ACC-5092-10 smoothly and monotonically decreases with the increase of adsorbed water and at saturation level it is lower by a factor of 2.5 as compared to the fully dehydrated material. In ACC-5092-20 clear break point was observed at water content of about 20% where radon adsorption sharply drops by a factor of 15. ACC-5092-10 was identified as a material that keeps its high radon adsorption ability even when saturated with water. Coupled with alpha-track detector it may be used for sensitive long-term measurements 222Rn measurements even at high levels of humidity.

Technical Scheme for Cutting Seedlings of Cyclocarya paliurus under Intelligent Control of Environmental Factors

Cyclocarya paliurus is a species with high economic, horticultural, and medicinal value. C. paliurus grows faster than other plants, increasing the demand for propagation through leaf and stem cuttings to produce seedlings. However, this species requires pre-control of environmental factors such as high temperatures (25–30 °C), humidity (80–90%), and specific light (2000 to 3000 lux) intensity levels during the cutting and seedling production process. However, it is difficult to predict suitable environments for the growth of C. paliurus. This study requires the use of big data technology to parameterize the method of intelligent control of the environment used in the process of making stakes and creating seedlings. Our main results were that an improved convolutional neural network and short long-term memory (LSTM) in big data technology were used with a new method, multipath hole convolution (MPCNN), to predict environmental factors in production of seedlings. Also, the research results show that the MPCNN and LSTM methods can accurately predict the necessary temperature, humidity, and light conditions in the production process of C. paliurus seedlings. For the prediction of environmental characteristics related to this species, the light characteristics have a high error distribution, but the method described here was able to accurately control this variation, with an error of less than 2%.

Highly sensitive humidity sensor based on cadmium selenide quantum dots-polymer composites: synthesis, characterization, and effect of UV/ozone treatment

This work describes the rational design of thin film-based cadmium selenide quantum dots (CdSe) mixed with conductive polyvinylidene fluoride (PVDF), inducing PVDF-CdSe composite for potential resistive humidity-sensing applications. The effect of UV/ozone treatment on surface hydrophilicity and sensing properties was investigated. AFM has been performed to examine the prepared films' texture, distribution over the surface, and size. Overall, the hydrophilicity of the developed films increases with UV radiation exposure time, leading to enhanced water vapor absorption without deforming the film surface. The sensor's sensitivity is improved with increasing UV radiation exposure. The electrical response of the PVDF-CdSe humidity sensors after 30 min of UV/ozone treatment reveals that at higher humidity levels (i.e., > 80% RH), the sensors exhibit an irregular response. However, at 20 min, treatment increases sensitivity and a linear change in impedance response concerning humidity level change compared to other samples. The hysteresis response was divided into two regions: the lower region, between 30 and 60% RH—where the maximum hysteresis loss was calculated to be 3%. While the higher area between 60 and 90% RH, where the maximum estimated hysteresis loss of the PVDF-CdSe sensor is around 14%, the UV/ozone treatment of the PVDF-CdSe nanocomposite film was found to enhance the sensing film's hydrophilicity without deforming the surface of the as-prepared PVDF-CdSe as well as the UV-treated films validates a potential for novel humidity sensors.

The heat is on: impacts of rising temperature on the activity of a common European mammal

Climate conditions severely impact the activity and, consequently, the fitness of wildlife species across the globe. Wildlife can respond to new climatic conditions, but the pace of human-induced change limits opportunities for adaptation or migration. Thus, how these changes affect behavior, movement patterns, and activity levels remains unclear. In this study, we investigate how extreme weather conditions affect the activity of European hares (Lepus europaeus) during their peak reproduction period. When hares must additionally invest energy in mating, prevailing against competitors, or lactating, we investigated their sensitivities to rising temperatures, wind speed, and humidity. To quantify their activity, we used the overall dynamic body acceleration (ODBA) calculated from tri-axial acceleration measurements of 33 GPS-collared hares. Our analysis revealed that temperature, humidity, and wind speed are important in explaining changes in activity, with a strong response for high temperatures above 25°C and the highest change in activity during temperature extremes of over 35°C during their inactive period. Further, we found a non-linear relationship between temperature and activity and an interaction of activity changes between day and night. Activity increased at higher temperatures during the inactive period (day) and decreased during the active period (night). This decrease was strongest during hot tropical nights. At a stage of life when mammals such as hares must substantially invest in reproduction, the sensitivity of females to extreme temperatures was particularly pronounced. Similarly, both sexes increased their activity at high humidity levels during the day and low wind speeds, irrespective of the time of day, while the effect of humidity was stronger for males. Our findings highlight the importance of understanding the complex relationships between extreme weather conditions and mammal behavior, critical for conservation and management. With ongoing climate change, extreme weather events such as heat waves and heavy rainfall are predicted to occur more often and last longer. These events will directly impact the fitness of hares and other wildlife species and hence the population dynamics of already declining populations across Europe.

Hydration and dehydration behaviors of poly(N-isopropylacrylamide)-grafted silica beads

The use of poly(N-isopropyl acrylamide) (PNIPAAm) in thermoresponsive interfaces for biomedical applications has been extensively investigated. Understanding the hydration and dehydration characteristics of PNIPAAm-grafted interfaces is crucial for the development of highly functional thermoresponsive interfaces. In this study, four PNIPAAm-grafted silica beads were prepared using atom transfer radical polymerization and radical polymerization techniques, with varying amounts of PNIPAAm grafted onto the beads. These PNIPAAm-grafted silica beads were used as samples, and their hydration and dehydration behaviors were analyzed using FTIR spectroscopy. Through the analysis of FTIR spectra obtained from the PNIPAAm-grafted silica beads prepared in this study, distinct observations were made under varying relative humidity and temperature conditions. Specifically, an elevation in the peak intensity of the broad peak at 3700–3000 cm−1, associated with the O-H group of hydrated water on PNIPAAm, was noted at higher humidity levels at 10°C. This increase in humidity resulted in an amplified peak intensity at 3700–3000 cm−1, indicative of the presence of the hydrated water molecules bonded to the PNIPAAm. Concurrently, shifts in the amide I and II peaks were observed with increasing relative humidity, signifying enhanced hydration and increased hydrogen bonding to C=O and N-H groups. Conversely, increasing the temperature at relatively high humidity led to a decreased in the intensity of the broad peak at 3700–3000 cm−1; this was attributed to the dehydration of the grafted PNIPAAm and subsequent water loss. The dehydration of PNIPAAm resulted in significant peak shifts for the amide I and II peaks, indicating a decrease in hydrogen bonding with the amide group. A significant change in peak intensity and shifts were evident, underscoring PNIPAAm brush's heightened propensity for hydration. These findings confirm the effectiveness of FTIR spectroscopy as a valuable approach for studying the hydration and dehydration behaviors of thinly grafted PNIPAAm layers on substrates.

Zero Threshold for Water Adsorption on MAPbBr3

Hybrid organic-inorganic perovskites (HOIPs) have shown great promise in a wide range of optoelectronic applications. However, this performance is inhibited by the sensitivity of HOIPs to various environmental factors, particularly high levels of relative humidity. This study uses X-ray photoelectron spectroscopy (XPS)to determine that there is essentially no threshold to water adsorption on the in situ cleaved MAPbBr3 (001) single crystal surface. Using scanning tunneling microscopy (STM), it shows that the initial surface restructuring upon exposure to water vapor occurs in isolated regions, which grow in area with increasing exposure, providing insight into the initial degradation mechanism of HOIPs. The electronic structure evolution of the surface wasalso monitored via ultraviolet photoemission spectroscopy (UPS), evidencing an increased bandgap state density following water vapor exposure, which is attributed to surface defect formation due to lattice swelling. This study will help to inform the surface engineering and designs of future perovskite-based optoelectronic devices.