Increase In Relative Humidity Research Articles

A Study on the Conditions of Fog Generation and the Change Rule of Fog Zone Length in Air Intake Roadway

Fog in mine air intake roadways is a non-negligible disaster that seriously reduces the visibility of the roadway, affects vehicle transportation and the safe passage of personnel, and jeopardizes the safe production of the mine. This paper applies both field testing and numerical simulation to explore fog formation conditions and the effects of inlet air temperature and humidity on the fog zone length within the Wangjialing Mine’s air intake roadway in Shanxi, China. First, based on the consideration of the relationship between the moisture gain of surrounding rock and the temperature with humidity of the air flow, the fog generation and distribution law model of the air intake roadway was established. Based on this model, the critical inlet air temperature and the critical inlet air relative humidity for fogging in the Wangjialing Mine air intake roadway were determined. In addition, we found that the fogging point inside the roadway shifted forward continuously with the increase in inlet air temperature and inlet air relative humidity, and the length of the fog zone expands parabolically in response to these rising conditions.

Applicability of Vegetation to Reduce Traffic-Borne PM2.5 Concentration in Roadside User Zones in Hot Arid Climates: The Case of Central Doha, Qatar

The ‘Beautification of Roads and Parks in Qatar’ is an urban development project that intends to provide space for exercising in roadside greenery in central Doha due to a lack of accessible open spaces. Considering the potential health risks associated with inhaling traffic-borne PM2.5, this study investigated the efficacy of four common road vegetation scenarios in reducing traffic-borne PM2.5 concentration in roadside user zones using ENVI-met. It examined Spearman’s rank correlation between air temperature, relative humidity, traffic emission rate, and PM2.5 concentration in roadside user zones. Based on the results, (1) hedgerows lower PM2.5 concentrations in roadside user zones, while trees significantly increase the concentration. (2) There is a strong association between air temperature and relative humidity and the PM2.5 concentration. The PM2.5 concentration decreases as air temperature increases but it increases as relative humidity increases. (3) There is a moderately negative association between the traffic emission rate and the PM2.5 concentration; however, this association is not found to be statistically significant. The ENVI-met simulation showed a slight overestimation of PM2.5 concentration compared to the wind tunnel simulation. These findings provide insight into planning road vegetation to reduce traffic-borne PM2.5 in roadside user zones in the local hot arid climate.

Influence of extraction and injection conditions on the performance of thermal-enhanced soil vapor extraction

Thermal-enhanced soil vapor extraction (T-SVE) is an in-situ remedial technique that can address the limitations of contaminant mass transfer and soil permeability. The relative humidity of the injected air, heating temperature of the thermal well, extraction pressure, and extraction mode are important design parameters of a T-SVE system that determine the temporal and spatial distributions of soil temperature and removal rate. Using a thermal–hydraulic–chemical coupled model with the interphase mass transfer of contaminants and water evaporation/condensation, this study investigated the effects of relative humidity, heating temperature, extraction pressure, and extraction mode on T-SVE performance. The results showed that with an increase in relative humidity, the heating temperature of the contaminated soil significantly improved; however, the removal rate of contaminants decreased, particularly in the late stage of remediation. Considering the heating temperature of the thermal well, a critical air relative humidity value that significantly affects the removal rate of contaminants was observed. The heating temperature of the thermal well must be considered in engineering design; however, the evaluation of the relative humidity of the air cannot be ignored.

Climate Change and Malaria Epidemics in the North-Eastern State of India, Mizoram

Malaria (P. falciparum, P. vivax) is a major vector borne disease in Mizoram. Since the extreme weather conditions and changing climate have a major role in the spread of vector borne illnesses, the purpose of this study aimed to examine the changing trend of climate and the relationship between climatic variables and epidemiological malaria situation in Mizoram. The Mann-Kendall and Sen’s slope test were employed to analyze the changing trend on rainfall and humidity, the climatic data were collected from Indian Meteorological Department, Aizawl (1986-2019) and multiple regression model has been utilized to observe the correlation between instances of malaria and climatic factors (2000-2019). The data on epidemiological malaria cases were obtained from Health and Family Welfare Department, Govt. of Mizoram. The Mann-Kendall results show declining trend in rainfall with -4.58 magnitude of rainfall annually and an increase in the annual relative humidity with 0.19% (p <0.1). The regression model shows a highly significant association between the climatic variables and the malaria situation showing p<0.05.

Noncontacting laser-based acousto-seismics at the laboratory scale: towards near-real-time monitoring of granular analogue models

Summary In this work we present a novel, experimentally-efficient setup for performing noncontacting laser vibrometry on geologic materials and their analogues. We show it is possible to acoustically monitor a granular material experiment in real time compared to the typical timescale of analogue modeling experiments. We acquire noncontacting waveform data with consistently high signal-to-noise-ratio (SNR). Compared to previously used standard contacting transducers, the novel joint use of sources and receivers that are both laser-based resulted in measured signals with improved waveforms and temporal bandwidths. These data acquisition improvements, in our case where surface waves are prominent in the data, enable enhanced multichannel surface wave processing, e.g., in terms of reliable dispersion curve estimates. We find, given the high waveform fidelity of our acquisition system, that the observed surface waves are highly sensitive to relatively small changes in in the medium’s elastic properties, making them a demonstrably reliable to monitor any processes that affect elasticity in these models in near-real time. As a demonstration, we continuously monitor a scaled analogue model containing granular glass beads. By continuously monitoring - i.e., performing repeatable active-source acousto-seismic surveys at short time-lapse intervals - over a period of ten hours, we find that an increase of relative humidity of 10% can lead to as much as a factor of two increase in surface wave group velocities. Finally, we discuss future applications of the developed method by considering surface wave inversion for fault and stress monitoring during the deformation of a model.

Novel kinetic modeling of photocatalytic degradation of ethanol and acetaldehyde in air by commercial and reduced ZnO: Effect of oxygen vacancies and humidity

A comprehensive kinetic model has been developed to address the factors and processes governing the photocatalytic removal of gaseous ethanol by using ZnO loaded in a prototype air purifier. This model simultaneously tracks the concentrations of ethanol and acetaldehyde (as its primary oxidation product) in both gas phase and on the catalyst surface. It accounts for reversible adsorption of both compounds to assign kinetic reaction parameters for different degradation pathways. The effects of oxygen vacancies on the catalyst have been validated through the comparative assessment on the catalytic performance of commercial ZnO before and after the reduction pre-treatment (10% H2/Ar gas at 500 °C). The influence of humidity has also been assessed by partitioning the concentrations of water molecules across the gas phase and catalyst surface interface. Given the significant impact of adsorption on photocatalytic processes, the beginning phases of all experiments (15 min in the dark) are integrated into the model. Results showcase a notable decrease in the adsorption removal of ethanol and acetaldehyde with an increase in relative humidity from 5% to 75%. The estimated number of active sites, as determined by the model, increases from 7.34 10−6 in commercial ZnO to 8.86 10−6 mol gcat−1 in reduced ZnO. Furthermore, the model predicts that the reaction occurs predominantly on the catalyst surface while only 14% in the gas phase. By using quantum yield calculations, the optimal humidity level for photocatalytic degradation is identified as 25% with the highest quantum yield of 6.98 10−3 (commercial ZnO) and 10.41 10−3 molecules photon−1 (reduced ZnO) catalysts.

New Insights into the Hygroscopic Character of Ionic Liquids: Study of Fourteen Representatives of Five Cation and Four Anion Families.

Over the past three decades, the synthesis of new ionic liquids (ILs) and the expansion of their use in newer applications have grown exponentially. From the beginning of this vertiginous period, it was known that many of them were hygroscopic, which in some cases limited their use or altered the value of their measured physical properties with all the problems that this entails. In an earlier article, we addressed the hygroscopic grade achieved by the ILs 1-ethyl-3-methylimidazolium chloride, 1-ethyl-3-methylimidazolium bromide, 1-ethyl-3-methylimidazolium methyl sulfate, 1-ethyl-3-methylimidazolium ethyl sulfate, 1-ethyl-3-methylpyridinium ethyl sulfate, 1-ethyl-3-methylimidazolium tosylate, 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium tetrafluoroborate, 1-dodecyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylpyridinium tetrafluoroborate, 1-butyl-1-methylpiperidinium bis(trifluoromethyl sulfonyl)imide, 1-methyl-1-propylpyrrolidinium bis(trifluoromethyl sulfonyl)imide, 1-butyl-1-methylpyrrolidinium bis(trifluoromethyl sulfonyl)imide, and methyl trioctyl ammonium bis(trifluoromethyl sulfonyl)imide. The objective was to determine the influence of the chemical nature of the compounds, exposed surface area, sample volume, agitation, and temperature. For this purpose, we exposed the samples to abrupt increases in relative humidity from 15 to 100% for days in an atmosphere chamber and then proceeded with the reverse process in a gentle manner. The results show that the sorption of water from the atmosphere depends on the nature of the IL, especially the anion, with the chloride anion being of particular importance (chloride ≫ alkyl sulfates~bromide > tosylate ≫ tetrafluoroborate). It has also been proven for the EMIM-ES and EMIM-BF4 samples that the mechanism of moisture capture is both absorption and adsorption, and that the smaller the exposed surface area, the higher the ratio of the mass of water per unit area.

Assessing the impact of green infrastructure on thermal comfort in relation to humidity: A case study in Korea

Problems arising from heatwaves and urban heat islands (UHIs) exacerbated by climate change have prompted diverse adaptation strategies. Although green infrastructure, which positively affects climate change adaptation, has been extensively evaluated, global-scale assessments of UHIs indicate that green infrastructure may not be sufficient to mitigate UHIs in humid regions with annual precipitation exceeding 1000 mm or summer precipitation exceeding 570 mm. However, these assessments primarily focused on UHIs; different results may be obtained for individual heat comfort. As relative humidity increases, the cooling effect of green areas potentially decreases. This suggests the need for additional studies on the impact of short-term precipitation, which increases relative humidity and induces cooling effects on green infrastructure. Korea experiences a humid summer due to the concentration of precipitation (approximately 711 mm of summer precipitation); thus, the contribution of green infrastructure to improving heat comfort might be limited. Therefore, this study investigated the impact of green infrastructure on thermal comfort in relation to precipitation levels using the Wet-Bulb Globe Temperature (WBGT) index and data from weather stations in Korea. Precipitation intensity was categorized into 2-day periods and 10 mm/day. Subsequently, thermal comfort was compared for summers from 1993 to 2022 according to the green infrastructure ratio around the stations. The results indicated that green infrastructure had a cooling effect on clear days but only had a cooling effect on precipitation days when the level of green infrastructure was above the critical ratio. Additionally, green infrastructure reduced the WBGT index if minimal precipitation occurred during the five-day cooling period following precipitation. While green infrastructure remains crucial for climate change adaptation, other strategies must be implemented to improve the thermal environment, particularly in areas with frequent precipitation.

Assessing the role of cold front passage and synoptic patterns on air pollution in the Korean Peninsula

Various numerical experiments using WRF (Weather Research & Forecasting Model) and CMAQ (Community Multiscale Air Quality Modeling System) were performed to analyze the phenomenon of rapidly high concentration PM2.5 after the passage of a cold front in an area with limited local emissions. The episode period was from January 14 to 23, 2018, and analysis was conducted by dividing it into two stages according to the characteristics of changes in PM2.5 concentrations during the period. Through the analysis of observational data during the episode period, we confirmed meteorological impacts (decrease in temperature, increase in wind speed and relative humidity) and an increase in air pollution (PM10 and PM2.5) attributed to the passage of a cold front. Using CMAQ's IPR (Integrated Process Rate) analysis, the contribution of the horizontal advection process was observed in transporting PM2.5 to Gangneung at higher altitudes, and the PM2.5 concentrations at the surface increased because the vertical advection process was influenced by the terrain. Notably, in Stage 2 (64 μg·m−3), a higher contribution of the vertical advection process compared to Stage 1 (35 μg·m−3) was observed, which is attributed to the differences in synoptic patterns following the passage of the cold front. During Stage 2, following the cold front, atmospheric stability (dominance of high-pressure system) led to air subsidence and the presence of a temperature inversion layer, creating favorable meteorological conditions for the accumulation of air pollutants. This study offers the mechanisms of air pollution over the Korean Peninsula under non-stationary meteorological conditions, particularly in relation to the passage of the cold front (low-pressure system). Notably, the influence of a cold front can vary according to the synoptic patterns that develop following its passage.

Research on the Effect of Spray Ventilation Cooling Systems on Human Physiological and Psychological Indexes

Hot working environment not only affects work efficiency, but also poses a potential threat to the physical and mental health of staff. The current common method for dealing with high temperatures is spray-only or ventilation-only. To investigate the impact of different spray and ventilation modes on indoor high-temperature environments, this study examined their effects on indoor environmental parameters, average skin temperature, and psychological indicators. By establishing an experimental platform for high-temperature thermal environments, a spray ventilation cooling system was implemented, and its cooling efficacy in the indoor thermal environment was analyzed. The environmental classification of the high-temperature working environment under experimental conditions is provided based on the experimental data. A comparison and analysis of environmental parameters and physiological and psychological indicators between moderate and high-temperature environments were conducted. The combination of spray and ventilation modes resulted in a 5.3 °C reduction in air temperature, a 24.1% increase in average relative humidity, and a 3.3 °C reduction in average Wet-bulb Globe Temperature (WBGT). The cooling effect was increased by 2.3 °C and the average relative humidity was increased by 10.8% compared to spray-only and ventilation-only modes. In spray and ventilation mode, when the spray volume is increased by 15 mL/min, the air temperature is reduced by 8.2 °C, the average relative humidity is increased by 31.9%, and the average WBGT is reduced by 5.1 °C. This study has guiding significance for finding a reasonable cooling scheme to cope with indoor high-temperature environments.

Development of a GSM-RC Automated Device for Measuring Mobile Communication Signal Strength and Meteorological Parameters

The automated Global System for Mobile Communication Signal Strength and Radio Climatological (GSM-RC) measuring device is an integration of different electronic sensors in a box for an in-situ measuring system. The sensor, data logging, and communication subsystems are integrated for transmitting information on meteorological parameters (MPs) and GSM signal strength level (SSL). The goal is to develop a device that could simultaneously measure MP and SSL of GSM communication systems in any location of interest. This is to reduce significant errors due to a lack of synchronization among multiple devices. To accomplish this objective, we designed an atmospheric sensing system with GSM SSL, temperature, relative humidity, and pressure sensors integrated as a GSM-RC unit. An Arduino microcontroller unit was used to wirelessly transmit the data collected by various sensors in each subsystem and stored on a micro-SD card. A statistical analysis of the SSL between the GSM-RC and the Samsung Galaxy A10s mobile reveals a correlation of roughly 0.99. The ANOVA analysis of variance demonstrates no noticeable distinction between the SSL from developed and conventional devices. The P-value is about 0.93, with α-value of 0.05. The MPs were validated with a standard Vintage Pro weather station, and the data were statistically correlated with accuracies close to unity. A field test was carried out with the device to measure the SSL through the GSM and the selected MP in Akure from January to December 2022. The findings indicate a weak and poor correlation between temperature and signal strength, while relative humidity and pressure have a positive and weak correlations with the signal strength. This implies that an increase in SSL leads to a slight decrease in temperature while the relative humidity and pressure increase slightly. Other than being affordable in terms of production and deployment, the device has also solved the problem of labour-intensiveness arising from bulkiness.

Geo-ecological, shoreline dynamic, and flooding impacts of Cyclonic Storm Mocha: A geospatial analysis

This research comprehensively assesses the aftermath of Cyclonic Storm Mocha, focusing on the coastal zones of Rakhine State and the Chittagong Division, spanning Myanmar and Bangladesh. The investigation emphasizes the impacts on coastal ecology, shoreline dynamics, flooding patterns, and meteorological variations. Employed were multiple vegetation indices—Normalized Difference Vegetation Index (NDVI), Enhanced Vegetation Index (EVI), Modified Vegetation Condition Index (mVCI), Disaster Vegetation Damage Index (DVDI), and Fractional Vegetation Cover (FVC)—to evaluate ecological consequences. The Digital Shoreline Assessment System (DSAS) aided in determining shoreline alterations pre- and post-cyclone. Soil exposure and flood extents were scrutinized using the Bare Soil Index (BSI) and Modified Normalized Difference Water Index (MNDWI), respectively. Additionally, the study encompassed an analysis of microclimatic variables, comparing meteorological data across pre- and post-cyclone periods. Findings indicate significant ecological impacts: an estimated 8985.46 km2 of dense vegetation (NDVI >0.6) was adversely affected. Post-cyclone, there was a discernible reduction in EVI values. The mean mVCI shifted negatively from −0.18 to −0.33, and the mean FVC decreased from 0.39 to 0.33. The DVDI underscored considerable vegetation damage in various areas, underscoring the cyclone's extensive impact. Meteorological analysis revealed a 245 % increase in rainfall (20.22 mm on May 14, 2023 compared to the May average of 5.86 mm), and significant increases in relative humidity (14 %) and wind speed (205 %). Erosion was observed along 74.60 % of the studied shoreline. These insights are pivotal for developing comprehensive strategies aimed at the rehabilitation and conservation of critical coastal ecosystems. They provide vital data for emergency response initiatives and offer resources for entities engaged in enhancing coastal resilience and protecting local community livelihoods.

Influence of Weather Parameters on the Development of Grey Mildew Disease in Cotton

A study was conducted at the Regional Agricultural Research Station in Warangal to investigate the impact of environmental factors on the development of grey mildew (Ramularia aerola Atk) in cotton. The research spanned from the Kharif season of 2019-20 to 2022-23 and focused on both Bt and non-Bt cotton genotypes grown in vertisols. Disease scores were recorded weekly on randomly selected labeled plants, and the percentage of disease intensity (PDI) was analyzed in relation to various weather parameters. Grey mildew was observed during the boll development stage up to the boll bursting stage, reaching its peak during the latter phase. Correlation analysis revealed significant negative associations between PDI and maximum temperature, minimum temperature, morning relative humidity, evening relative humidity, rainfall, and the number of rainy days. These findings indicate that these environmental factors influenced the development of the disease in both Bt and non-Bt genotypes. Furthermore, multiple linear regression analysis of PDI demonstrated that one percent increase in evening relative humidity led to a corresponding increase in the percent disease index of grey mildew. Specifically, in Bt (RCH 2 BG II) genotype, the increase was 0.38%, while in non-Bt (LRA-5166) genotype, it was 1.87%. Consequently, the study suggests the implementation of preventive and/or protective measures, such as the use of recommended fungicides like 0.3% wettable sulphur or 0.1% carbendazim.

Climate influences scrub typhus occurrence in Vellore, Tamil Nadu, India: analysis of a 15-year dataset

Climate is one of the major factors determining the prevalence and seasonality of vector borne diseases like scrub typhus (ST). We analyzed, the association of the meteorological factors like temperature, rainfall and humidity with scrub typhus using the 15 years scrub typhus data from a tertiary care hospital in Vellore, South India. Demographic data of permanent residents of Vellore, who had IgM ELISA results for scrub typhus for the time period of May 2005 to April 2020 were included. Meteorological data was correlated with the monthly scrub typhus cases; negative binomial regression model was used to predict the relation between scrub typhus occurrence and climate factors. Maximum number of ST cases were reported between the months August and February with October recording the highest number of cases. Elderly people, farmers, agricultural workers and housewives were at higher risk for scrub typhus. For an increase of 1 °C in mean temperature, the monthly ST cases reduced by 18.8% (95% CI − 24.1, − 13.2%). On the contrary, for 1 percent increase in mean relative humidity (RH), there is an increase of 7.6% (95% CI 5.4, 9.9%) of monthly ST cases. Similarly, an increase of 1 mm of rainfall contributed to 0.5 to 0.7% of monthly ST cases (after 2 months) depending on the variables included in the analysis. This study provides information that meteorological factors influence ST occurrence in Vellore. The rise of scrub typhus cases is maximal 2 months post rainfall. Whereas a rise in relative humidity, causes a rise in scrub typhus cases in same month, while rise in temperature has a negative impact on scrub typhus during the same month. These findings based on a retrospective analysis need validation by prospective studies.

Ambient atmospheric application and influencing factors of ozone catalytic decomposition materials in a channel test

Surface ozone pollution is a significant environmental problem. In addition to the control of ozone precursors, direct catalytic decomposition of ozone is an effective control method with broad prospects. At present, the evaluation of the ozone decomposition performance of catalysts is typically performed in the laboratory, and the lack of scientific evaluation means to apply them to complex ambient atmosphere limits the practical application of ozone removal catalysts. Here, we devised a new evaluation method for ozone catalytic decomposition materials in the ambient atmosphere that can comprehensively evaluate the influence of various factors in the ambient atmosphere on performance. The results showed that ozone catalytic decomposition materials can maintain a decomposition efficiency of more than 20% in ambient atmosphere. The decomposition efficiency is mainly affected by distance, the closer the distance; the higher the decomposition efficiency. In addition, the concentration of ozone in the environment also affects the decomposition efficiency and shows a positive correlation. As the ozone concentration increased, the decomposition efficiency increased. An increase in relative humidity can cause a decline in decomposition efficiency, but this effect is eliminated with a decrease in humidity. In addition, the ozone catalytic decomposition materials can reduce the ozone concentration in the environment from 160 μg/m3to less than 100 μg/m3, which can play a great role in environmental ozone pollution control.

Enhanced dielectric properties of poly(vinylidene fluoride) matrix nanocomposites incorporated with one–dimensional structure of titanate nanotubes

The dielectric properties of polymer nanocomposites based on a poly(vinylidene fluoride) (PVDF) matrix, filled with a one–dimensional nanostructure of titanate nanotubes (TNTs), were investigated. These studies demonstrated significant improvements in the energy storage capability of the application. The TNTs were synthesized through an alkali hydrothermal treatment method at 130 °C for 24 h, using a 10 M NaOH solution. The TNTs exhibited a large dielectric permittivity of approximately 1.2 × 104 with a low loss tangent of approximately 0.12 at 1 kHz and 25 °C. TNTs/PVDF polymer nanocomposites were studied and fabricated using liquid phase–assisted dispersion and hot–pressing methods. By introducing TNTs into the PVDF polymer, both the dielectric permittivity and loss tangent increased. Notably, the polymer nanocomposite containing 50 wt. % TNTs exhibited a dielectric permittivity of 5.3 × 103 at 1 kHz, which is ∼530 times greater than that of pure PVDF (10.78), while the loss tangent remained at 0.572. The low–frequency dielectric permittivity increased with an increase in relative humidity from 50 to 95 % due to enhanced interfacial polarization at the surface and electrode interface. However, at frequencies greater than 1 kHz, the dielectric permittivity was independent of relative humidity. The improvement in the enhanced dielectric permittivity of polymer–based nanocomposites with incorporated TNTs was ascribed to these factors.

Wintertime fine aerosol particles composition and its evolution in two megacities of southern and northern China

Study on fine aerosols composition can help understand the particles formation and is crucial for improving the accuracy of model simulations. Based on field data measured by a Q-ACSM (Quadrupole-Aerosol Chemical Speciation Monitor), we have comprehensively compared the characteristics, evolution, and potential formation mechanisms of the components in NR-PM2.5 during wintertime at two megacities (Beijing and Guangzhou) of southern and northern China. We show that as PM pollution intensifies, the mass fraction of the primary aerosols (e.g., COA, HOA) in PM2.5 in Guangzhou increased, along with a slight decline in proportion of both the secondary organic (SOA) and inorganic (SIA) aerosols; In contrast, in Beijing, the proportion of the SIA ramped up from 28 % to 53 % with the pollution evolution; and the fraction of SOA in total OA also increased due to a substantial increment in the proportion of MO-OOA (from 29 % to 48 %), suggesting a significance of the secondary processes in worsening aerosols pollution in Beijing. Our further analysis demonstrates a leading role of aqueous pathway in the secondary formation of aerosols at the Beijing site, presenting an exponential rising of SIA and SOA with the relative humidity (RH) increase. Compared to Beijing, however, we find that the photochemical oxidation other than aqueous process in Guangzhou plays a more critical role in those secondary aerosols formation. Combined with the Hysplit trajectory model, we identify the high humid conditions in Guangzhou are typically affected by clean marine air masses, explaining the slower response of secondary components to the RH changes. Moreover, the particles in Guangzhou were observed less hygroscopic that is adverse to the aerosol aqueous chemistry. The results provide basis for the precise control of PM pollution in different regions across China and would be helpful in improving model simulations.

Measurement and analysis of the air quality within a high-speed train carriage in a region of Southwest China

To investigate the air quality status and identify factors influencing air pollution, data on CO2, formaldehyde, PM2.5, PM10, temperature, and humidity were measured in a high-speed train carriage of the Changsha-Zhuzhou intercity in southwest China. In the test section, CO2, formaldehyde, relative humidity, and temperature exceeded the standard levels, and their compliance rates were 84%, 96%, 84%, and 76%, respectively. Then the influencing factors of pollutants were analyzed from three aspects: driving environment, the number of passengers, and relative humidity. Results show that the percentage of PM2.5 to PM10 in tunnel environments was higher; the increase in the number of passengers led to the elevation of CO2 concentration in the carriage, while only in the ground environment, the number of passengers significantly correlated with particulate matter; the increase in relative humidity promotes the production and release of particulate matter and formaldehyde. Finally, fitting relationships between relative humidity and formaldehyde, as well as the number of passengers and CO2 were established to predict the air quality status. It indicated that when the relative humidity of the carriage is less than 73%, the formaldehyde solubility was easy to exceed standards, and when the number of passengers was greater than 70, the CO2 was easy to exceed standards.

Research on the influence of relative humidity on the purification efficiency of sponge activated carbon system purification system

An indoor air purification system coupled with adsorption and heat storage was designed based on a prefabricated building, which has the advantages of high purification efficiency, does not take up indoor space and does not require additional power consumption. It has been shown that the relative humidity has a significant impact on the purification effect of particulate matter. Using sponge activated carbon as adsorption material, the effect of different relative humidity on the purification efficiency of PM2.5 and PM10 was experimentally studied, and the purification effect of the purification system on PM2.5 and PM10 under various relative humidity conditions was analyzed. The results show that in the relative humidity interval of 20%-70%, with the increase of relative humidity, the sponge activated carbon purification system shows an increasing trend in the purification efficiency of PM2.5, and the effect on the purification efficiency of PM10 is not obvious.

Experimental investigation of flow characteristics of a jet in low atmospheric pressure conditions on the Tibetan Plateau

The indoor humidity of heated buildings on the Tibetan Plateau can be as low as 5%RH. Indoor air humidification is very important to people's life and health. Due to the low atmospheric pressure on the plateau, the air physical parameters and wet component diffusion characteristics are different from those of standard atmospheric pressure. This paper investigates experimentally the effects of horizontal and vertical wet jets with various initial velocities, pipe diameters, ambient temperatures, and moisture temperatures on the indoor temperature and humidity field. It is shown that low atmospheric pressure will lead to an increase in relative humidity nearly the jet outlet, but the effective moisture delivery distance becomes shorter and the actual moisture load increases. When the same relative humidity is reached, the specific humidity under low atmospheric pressure is about 1.5–2.5 times as that under standard atmospheric pressure. The average relative humidity of jets produced by the ultrasonic humidification source is 10% higher than the evaporative humidification source during the same time. During the actual humidification process, it is necessary to consider the balance between the initial velocity of the jet and the humidification distance and select the jet tube diameter according to the humidification space area. Additionally, choosing a jet with a temperature slightly higher than the ambient temperature can avoid reducing the indoor temperature. This study should be helpful to the plateau humidification jet characteristics and parameter selection.