Increase In Absolute Humidity Research Articles

Short-term effect of meteorological factors on COVID-19 mortality in Qom, Iran

ABSTRACT The present study was conducted to assess the short-term effects of the meteorological factors on the COVID-19 mortality in Qom, Iran. The GAM with a quasi-Poisson link function was used to evaluate the impact of temperature, DTR, relative humidity, and absolute humidity on the COVID-19 mortality, controlling potential confounders such as time trend, air pollutants, and day of the week. The results showed that the risk of COVID-19 mortality was reduced, in single-day lag/multiple-day average lag, per one-unit increase in absolute humidity (percentage change in lag 0=−33.64% (95% CI (−42.44, −23.49)), and relative humidity (percentage change in lag 0=−1.87% (95% CI (−2.52, −1.22)). Also, per one-unit increase in DTR value, COVID death risk increased in single-day and multiple-day average lag. This study demonstrated a significant relationship between the four meteorological variables and the COVID-19 mortality.

The influence of vapor on the particle transport in high humid neighborhood environment

The particle transport characteristics have a significant effect on the exposure of residents and pedestrians to traffic pollutants in the street canyon. Around the lakeside environment, the diffusion of water vapor affects the flow characteristics of the gas mixture, which has a considerable influence on particle transport in the street canyon. A computational domain containing water bodies from which droplets were emitted by evaporation, a lakeside avenue and architectural groups were constructed. The RNG k-ε turbulence model and discrete phase model were applied to study the velocity, pressure, density of the airflow and particle transport characteristics in the street canyon with the absolute humidity increase (AHI) of 0, 3.8×10-4 g/kg, 1.7×10-3 g/kg, 3.1×10-3 g/kg. The saturated vapor pressure on the surface of droplets was modified by the pressure correction equation, which can limit the evaporation rate of the droplets. The simulation results demonstrated that, the diffusion of vapor could reduce the airflow velocity and increase the air pressure and density. The particle concentration in the street canyon increased with the AHI. Most of the pathogens in the air are transmitted with the flow of particle, and the study has some guiding significance to prevent the transmission of viruses.

Experimental analysis of the air humidification process for humid air turbine cycle using a two-phase measurement system

The humid air turbine (HAT) cycle utilizes the low-temperature heat from the gas turbine exhaust to humidify the air, thereby increasing the specific output work. The air humidification process has a significant impact on gas turbine efficiency. So far, there is still a lack of reliable experimental data from gas-liquid two-phase flow, which limits the in-depth study of the air humidification process. In this work, the new multi-point gas–liquid two-phase temperature and relative humidity measurement system suitable for countercurrent pressurized humidifier is re-designed, the temperature and relative humidity distributions of humid air and the water temperature distribution are obtained along the height of humidifier. The effects of the water–air ratio and inlet water temperature on the humidification process are thoroughly investigated. The water–air ratio has little effect on the outlet air temperature, and it has a significant effect on the air and water temperature in the packing segment, and the relative humidity and absolute humidity increase as the water–air ratio increases. The outlet air temperature and water temperature increase as the inlet water temperature improves. The sooner the air reaches saturation and the absolute humidity increases more significantly at higher inlet water temperature. Vapor condensation occurs at the interface during the humidification process. Besides, the outlet water temperature can be cooled to be lower than the wet bulb temperature of the inlet air, but always higher than the dew point temperature of the inlet air. The measurement data provide an experimental basis for studying the heat and mass transfer inside the humidifier.

Tree cooling effects and human thermal comfort under contrasting species and sites

The potential of urban greenspaces in regulating temperature is widely known; however, in the heterogeneous urban landscape the process and the magnitude of human thermal comfort as well as the cumulative effects of natural and built surfaces are not yet well understood. We selected two ecologically contrasting species Tilia cordata Mill. and Robinia pseudoacacia L. planted in eight plots across five different sites in Würzburg, one of the major cities in Northern Bavaria, Germany. We monitored meteorological and edaphic variables and tree sap-flow along with the air temperature, relative humidity, within tree canopy and outside, between January 1 and December 31, 2018. Additionally, we measured surface temperature, meteorological variables below the tree canopies and outside, during the hottest summer days of 2018 (July 23 to 31). With 35% higher leaf area index, T. cordata tree canopies prevented higher incoming radiation compared to R. pseudoacacia trees. Moreover, with diffuse porous wood anatomy, T. cordata trees provided four times more transpiration compared to R. pseudoacacia, therefore, up to 2.8 °C air temperature reduction (ΔAT) within the tree canopy, and increase in absolute humidity (ΔAH) up to 2.6 g m − 3 compared to the 1.9 °C of ΔAT and 1.9 g m − 3 of ΔAH for R. pseudoacacia respectively. Thus, physiological equivalent temperature reduction was up to 4 °C under the shade of a R. pseudoacacia tree compared to 11 °C under a T. cordata tree. Finally, the research showed the importance of urban topography, such as street orientation, surrounding environment such as geometry, urban design to reduce the hindrance of wind flow and proportion of greenspaces in terms of outdoor human thermal comfort.

Characteristics of summer heat stress in China during 1979‒2014: climatology and long-term trends

Heat stress describes the joint effects of high temperature and humidity. It poses severe impacts on public health and socioeconomic activities. However, its characteristics have not been fully investigated. Here we conduct a comprehensive examination of the climatological pattern and long-term trends of summer heat stress occurrences across China during 1979–2014. We find that China experienced severe heat stress conditions, particularly in densely populated and urbanized areas such as North China, the Yangtze River valley, and South China. Heat stress events in all these subregions are accompanied by decreased relative humidity (RH), and suppressed surface pressure and precipitation. Heat stress in China is mainly caused by high temperature, rather than high RH. Moreover, heat stress in most regions of China has increased noticeably during the past decades. Nationwide apparent temperature (AT, or heat index) and temperature (T) have increased by 0.37 and 0.35 °C decade−1, respectively. The yearly frequencies of cautionary, extreme cautionary, and dangerous heat stress days have increased by 0.92, 0.67, and 0.03 days decade−1, respectively. It is noticed that AT, T, and absolute humidity increase and RH decreases in most parts of China, suggesting that saturated water vapor pressure increases faster than actual water vapor pressure with rising temperature.

How environmental conditions impact mosquito ecology and Japanese encephalitis: An eco-epidemiological approach

Japanese encephalitis (JE) is one of the major vector-borne diseases in Southeast Asia and the Western Pacific region, posing a threat to human health. In rural and suburban areas, traditional rice farming and intensive pig breeding provide an ideal environment for both mosquito development and the transmission of JEV among human beings. Combining surveillance data for mosquito vectors, human JE cases, and environmental conditions in Changsha, China, 2004–2009, generalized threshold models were constructed to project the mosquito and JE dynamics. Temperature and rainfall were found to be closely associated with mosquito density at 1, and 4month lag, respectively. The two thresholds, maximum temperature of 22–23°C for mosquito development and minimum temperature of 25–26°C for JEV transmission, play key roles in the ecology of JEV. The model predicts that, in the upper regime, a 1g/m3 increase in absolute humidity would on average increase human cases by 68–84%. A shift in mosquito species composition in 2007 was observed, and possibly caused by a drought. Effective predictive models could be used in risk management to provide early warnings for potential JE transmission.

Linking climate and air quality over Europe: effects of meteorology on PM<sub>2.5</sub> concentrations

Abstract. The effects of various meteorological parameters such as temperature, wind speed, absolute humidity, precipitation and mixing height on PM2.5 concentrations over Europe were examined using a three-dimensional chemical transport model, PMCAMx-2008. Our simulations covered three periods, representative of different seasons (summer, winter, and fall). PM2.5 appears to be more sensitive to temperature changes compared to the other meteorological parameters in all seasons. PM2.5 generally decreases as temperature increases, although the predicted changes vary significantly in space and time, ranging from −700 ng m−3 K−1 (−8% K−1) to 300 ng m−3 K−1 (7% K−1). The predicted decreases of PM2.5 are mainly due to evaporation of ammonium nitrate, while the higher biogenic emissions and the accelerated gas-phase reaction rates increase the production of organic aerosol (OA) and sulfate, having the opposite effect on PM2.5. The predicted responses of PM2.5 to absolute humidity are also quite variable, ranging from −130 ng m−3 %−1 (−1.6% %−1) to 160 ng m−3 %−1 (1.6% %−1) dominated mainly by changes in inorganic PM2.5 species. An increase in absolute humidity favors the partitioning of nitrate to the aerosol phase and increases the average PM2.5 during summer and fall. Decreases in sulfate and sea salt levels govern the average PM2.5 response to humidity during winter. A decrease of wind speed (keeping the emissions constant) increases all PM2.5 species (on average 40 ng m−3 %−1) due to changes in dispersion and dry deposition. The wind speed effects on sea salt emissions are significant for PM2.5 concentrations over water and in coastal areas. Increases in precipitation have a negative effect on PM2.5 (decreases up to 110 ng m−3 %−1) in all periods due to increases in wet deposition of PM2.5 species and their gas precursors. Changes in mixing height have the smallest effects (up to 35 ng m−3 %−1) on PM2.5 . Regarding the relative importance of each of the meteorological parameters in a changed future climate, the projected changes in precipitation are expected to have the largest impact on PM2.5 levels during all periods (changes up to 2 μg m−3 in the fall). The expected effects in future PM2.5 levels due to wind speed changes are similar in all seasons and quite close to those resulting from future precipitation changes (up to 1.4 μg m−3). The expected increases in absolute humidity in the future can lead to large changes in PM2.5 levels (increases up to 2 μg m−3) mainly in the fall due to changes in particulate nitrate levels. Despite the high sensitivity of PM2.5 levels to temperature, the small expected increases of temperature in the future will lead to modest PM2.5 changes and will not dominate the overall change.

Influence of changes in humidity on dry temperature in GPS RO climatologies

Abstract. Radio occultation (RO) data are increasingly used in climate research. Accurate phase (change) measurements of Global Positioning System (GPS) signals are the basis for the retrieval of near-vertical profiles of bending angle, microwave refractivity, density, pressure, and temperature. If temperature is calculated from observed refractivity with the assumption that water vapor is zero, the product is called "dry temperature", which is commonly used to study earth's atmosphere, e.g., when analyzing temperature trends due to global warming. Dry temperature is a useful quantity, since it does not need additional background information in its retrieval. However, it can only be safely used as proxy for physical temperature, where moisture is negligible. The altitude region above which water vapor does not play a dominant role anymore, depends primarily on latitude and season. In this study we first investigated the influence of water vapor on dry temperature RO profiles. Hence, we analyzed the maximum altitude down to which monthly mean dry temperature profiles can be regarded as being equivalent to physical temperature. This was done by examining dry temperature to physical temperature differences of monthly mean analysis fields from the European Centre for Medium-Range Weather Forecasts (ECMWF), studied from 2006 until 2010. We introduced cutoff criteria, where maximum temperature differences of −0.1, −0.05, and −0.02 K were allowed (dry temperature is always lower than physical temperature), and computed the corresponding altitudes. As an example, a temperature difference of −0.05 K in the tropics was found at an altitude of about 14 km, while at higher northern latitudes in winter it was found at an altitude of about 9–10 km, in summer at about 11 km. Furthermore, regarding climate change, we expect an increase of absolute humidity in the atmosphere. This possible trend in water vapor could yield a wrongly interpreted dry temperature trend. As a consequence, we performed a model study, investigating the increase in height of the transition region between moist and dry air. We used data from the fifth phase of the Coupled Model Intercomparison Project (CMIP5), analyzing again monthly mean dry temperature to physical temperature differences, now from the years 2006 to 2050. We used the highest emission scenario RCP8.5 (representative concentration pathway), studying all available models of the CMIP5 project, analyzing one internal run per model, with the goal to identify the altitude region where trends in dry temperature can be safely regarded as reflecting trends in physical temperature. From all models we therefore choose a selection of models ("max 8" CMIP5 models), which showed the largest trend differences. As a result, our trend study suggests that the lower boundary of the region where dry temperature is essentially equal to physical temperature rises about 150 m decade−1.

Influence of air pressure and humidity on positive direct current corona discharge performances of the conductor in a corona cage

SUMMARY With the implementation of West-to-East Power Transmission Project in China, transmission lines will inevitably pass through high altitude regions with complex atmospheric conditions. The effects of such atmospheric parameters as pressure and humidity on the corona discharge performances of conductors are complicated. Especially as to the effect of air humidity on corona inception voltage, researchers have not reached an agreement. Therefore, by adjusting air pressure and air humidity in a corona cage, the positive direct current corona discharge performances of a smooth steel tube are tested. Results indicate that corona inception voltage increases significantly with the increase of air pressure, and the calculated results by discharge model are in accordance with measured results. Yet, with the increase of absolute humidity, corona inception voltage increases slowly. Under high humidity condition, corona inception voltage decreases because of the condensation on conductor surface, which distorts the surface electric field. In view of the condensation, the calculating model is improved, whose calculated results are in line with measured results. Moreover, it is found that inception discharge is easier to turn into glow discharge under low pressure and low humidity condition. The average pulse amplitude decreases with the increase of humidity, but with the increase of pressure, it decreases first and then increases. The rising time of the discharge pulse presents increasing trend with the increase of both air pressure and air humidity. All the test results are analyzed from microscopic mechanism. Copyright © 2013 John Wiley & Sons, Ltd.

Effects of air pressure and humidity on the corona onset voltage of bundle conductors

On the condition of adjusting air pressure from 58.7 to 98.7 kPa and air humidity from 5 to 17.3 g/m3 in the multifunctional artificial chamber, experiments on AC corona performance of scaled models of three kinds of bundle conductors are conducted and the mathematical model of corona discharge is proposed to calculate the corona onset voltages. Results indicate that the corona onset voltage of bundle conductors will decrease obviously with the decrease of air pressure, but the effect of air pressure on the corona onset voltage will decline with the increase of absolute humidity. When absolute humidity rises from 5 to 15 g/m3, the corona onset voltage increases slowly. Furthermore, the lower air pressure is, the more obvious effect of absolute humidity on the corona onset voltage is. Yet, the corona onset voltage drops remarkably when absolute humidity reaches 17.3 g/m3, owing to the condensation, which distorts the surface electric field, on the surface of conductors under high-humidity condition. In light of the condensation effect, the mathematical model of corona discharge is improved, which helps yield agreement between the measured results and the calculated results. Moreover, formulas for predicting corona onset voltages under various bundle configurations, air pressure and air humidity are also obtained. Calculated results from these formulas along with from mathematical models are compared with the measured results.

Artificial neural networks for predicting diffusible hydrogen content and cracking susceptibility in rutile flux-cored arc welds

The aim of the current work was to build and validate a back propagation artificial neural network (BPANN) to predict the level of diffusible hydrogen ( H D) based on a variety of flux-cored arc welding (FCAW) parameters such as welding current, contact-tip to work piece distance (CTWD) and shielding gas type for single run, horizontal bead-on-plate steel welds using seamed and seamless rutile consumable wires (Model 1). A probabilistic artificial neural network model (PANN) was then applied to determine the likelihood of hydrogen assisted cold cracking (HACC) in a gapped bead-on-plate (GBOP) test based on the level of H D and welding preheat temperature (Model 2). This approach could be applied to ‘real life’ situations with the availability of sufficient data. Results are also presented for a sensitivity analysis for Model 1, which identifies the key input variables and the effect they have on the output, H D. It was determined that the consumable type and the CTWD were the key variables. A seamless consumable with a H5 classification and an increase in the CTWD, as well as increases in current led mostly to a decrease in the level of diffusible hydrogen. Additionally, Model 1 predicted that using a 25%CO 2–75%Ar shielding gas, instead of 100%CO 2, and an increase in absolute humidity (a function of relative humidity and temperature) in the surrounding atmosphere led to an increase in diffusible hydrogen deposited into the weld metal (WM). Finally, based on the predictions of Model 2 it was established that for the given welding conditions hydrogen cracking in a GBOP test could be avoided by maintaining hydrogen levels at less than ∼3 mL/100 g or using a preheat temperature slightly higher than 100 °C. Analysis of the data also led to the conclusion that further data were required for the GBOP tests when the hydrogen levels were between 4 and 8 mL/100 g to correct and improve confidence in this part of the model.

Sensitivity of ozone to summertime climate in the eastern USA: A modeling case study

The goal of this modeling study is to determine how concentrations of ozone respond to changes in climate over the eastern USA. The sensitivities of average ozone concentrations to temperature, wind speed, absolute humidity, mixing height, cloud liquid water content and optical depth, cloudy area, precipitation rate, and precipitating area extent are investigated individually. The simulation period consists of July 12–21, 2001, during which an ozone episode occurred over the Southeast. The ozone metrics used include daily maximum 8 h average O 3 concentration and number of grid cells exceeding the US EPA ambient air-quality standard. The meteorological factor that had the largest impact on both ozone metrics was temperature, which increased daily maximum 8 h average O 3 by 0.34 ppb K −1 on average over the simulation domain. Absolute humidity had a smaller but appreciable effect on daily maximum 8 h average O 3 (−0.025 ppb for each percent increase in absolute humidity). While domain-average responses to changes in wind speed, mixing height, cloud liquid water content, and optical depth were rather small, these factors did have appreciable local effects in many areas. Temperature also had the largest effect on air-quality standard exceedances; a 2.5 K temperature increase led to a 30% increase in the area exceeding the EPA standard. Wind speed and mixing height also had appreciable effects on ozone air-quality standard exceedances.

In vivo efficacy of heated and non-heated humidifiers during nasal continuous positive airway pressure (nCPAP)-therapy for obstructive sleep apnoea

Upper airway dryness is a frequent side-effect of nasal continuous positive airway pressure therapy (nCPAP) in obstructive sleep apnoea (OSA). In this situation, heated or non-heated passover humidifiers are often added to the nCPAP-therapy. The efficacy of these two modes in terms of increasing the absolute humidity of the inspired air in vivo has so far not been established. The present investigation was therefore designed to compare various heated and non-heated passover humidifiers in terms of the their ability to increase the absolute humidity in the inspired air during nCPAP.In six healthy test individuals, nCPAP-therapy at pressures of 5 mbar and 10 mbar was simulated, and the relative humidity and temperature of the air within the tube at the junction between CPAP tube and mask were measured. In each test person, measurements were carried out both with and without the two heated (HC 100®, Fischer&Paykel Inc., New Zealand and HumidAire®, ResMed Ltd., Australia) and two non-heated (Oasis®and Humidifier®, both from Respironics Inc., U.S.A.) passover humidifiers under steady-state conditions. The absolute humidity was calculated from the relative humidity and temperature measurements.The mean (SD) absolute humidity (gm−3) in the steady-state was significantly (P<0·05 higher with each of the humidifiers than that calculated when no humidifier was used. The relevant figures were as follows: no humidifier: 10·2 (1·8) gm−3(at 5 mbar)/9·8 (1·8) gm−3(at 10 mbar); Humidifier®: 16·4 (0·97)/15·6 (1·26); Oasis®: 17·3 (0·97)/16·7 (0·93); HC100®: 26·5 (1·40)/26·2 (1·23); HumidAire®: 31·8 (2·50)/30·9 (2·64). The mean increase in absolute humidity (in gm−3) with the aid of the heated humidifiers was 16·3 (5 mbar) gm−3/16·4 (10 mbar) gm−3with HC100®and 21·6/21·1 with HumidAire®, and in both cases was clearly and significantly (P=0·028) higher in comparison with the non-heated humidifiers—6·2/5·8 with Humidifier®and 7·2/6·9 with Oasis®.In terms of the absolute humidity achieved within the CPAP tube system, the heated humidifiers were clearly superior to the non-heated humidifiers. These results were, however, obtained under laboratory conditions, and therefore cannot be translated unreservedly to the situation represented by long-term CPAP-treatment. Furthermore, it is possible that the smaller humidification capacity of the non-heated humidifiers may still suffice to meet the requirements of clinical use in terms of effectively preventing dry airways under CPAP treatment. This point, however, needs further investigation on the basis of long-term clinical studies.

Comparison of non-evaporative heat transfer in different cattle breeds

Tissue conductance and non-evaporative heat loss from the skin were determined from measurements of body temperature, evaporative water loss, metabolic rate and heat storage in six steers in each of three breeds, Brahman (B), Brahman x Hereford-Shorthorn (BX) and Shorthorn (S). A group of six steers, two from each breed, remained in a climate room set at 25�C overnight, and during the following day all were exposed for 1 h to sequential increases in air temperature (28, 32, 37, 41, 43, 45�C). Each steer was measured at 25�C and after a 30-min exposure to each temperature. Tissue conductance increased with air temperature (Ta), reaching maximum values at 41�C, the rate of increase (W m-2 'C-I per degree rise in Ta) being for B 3.95, for BX 2.33 and for S 2,09. Between 41 and 45�C, tissue conductance remained constant in B but declined in BX and S with a concurrent increase in heat storage. Mean tissue conductance (W m-2 �C-1) of B was 63.5; BX, 56.1; and S, 47.8, values that were significantly different (P &lt; 0.01). Expressed in terms of metabolic weight, the breed means of tissue conductance (litres O2 h-1 W-0.75 �C-1) were also significantly different: B, 0.56; BX, 0.43; and S, 0.33 (P &lt; 0.005), with the relative differences similar to those calculated per unit area. Breed differences in tissue conductance may be related to variations in ability to redirect blood from the core to the skin. Non-evaporative heat loss comprised 55-65% of the total heat loss from the skin in all breeds at Ta of 25�C. The remaining heat was lost through sweating. As Ta increased and approached skin temperature, non-evaporative heat loss decreased but in B and BX remained 25% of the total heat loss from the skin. S steers, in contrast, sustained little non-evaporative heat loss as Ta increased because sweating rates increased 50% more than that required to dissipate the heat at the skin. The increase in absolute humidity of the chamber was associated with the excessive sweating in this breed.

Cloud Optics as a Possible Stabilizing Factor in Climate Change

Calculations made with a one-dimensional radiative-convective climate model show that the optical properties of clouds in solar wavelengths can be a stabilizing factor in climate change. Cloud reflectivity and absorption have been calculated as functions of cloud liquid water content using the parameterization of Liou and Wittman (1979). With the assumption that cloud liquid water content increases (decreases) as temperature and absolute humidity increase (decrease) during a climate perturbation, cloud reflectivity increases (decreases), damping the original perturbation by a few tens of percent. This probably should be regarded as an upper limit on the amount of negative feedback which changes in solar wavelength cloud optical properties (for fixed cloud area) can provide in a global climate model.

EFFECT OF UREA ON FINE STRUCTURE OF NYLON 6 FIBER DURING HIGH TEMPERATUTE STEAMING WITH HUMID AIR

In the previous paper, it has been reported that heat conduction in a paper cylinder during high temperature steaming with humid air was considerably affected by the presence of urea. In the present paper, the effect of urea on the fine structure of nylon 6 fiber treated by high temperature steaming with humid air was investigated under various conditions of absolute humidity.Furthermore, nylon 6 fiber and filament were treated with various compositions of urea/water solution heated to 140°C in order to investigate in some detail the effect of urea during the steaming. Change of fine structure was observed by X-ray diffraction patterns. Further, crystallite size, lattice spacing and crystallinity were measured by means of X-ray diffractometer and density gradient tube.The following results were obtained:(1) Shrinkage of nylon 6 filament treated by the steaming increased with an increase of absolute humidity, particularly in the presence of urea. Crystal_??_size also increased.(2) Shrinkage, crystallinity and water absorption of nylon 6 fiber treated with hot solution of various compositions of urea/water increased with an increase of water content in treating medium.

Diurnal and seasonal changes in bovine respiratory functions in a subtropical climate

The respiratory responses of four Israeli-Holstein heifers sheltered from direct solar radiation were measured every 4 hr during 4 consecutive days in early spring and again in late summer. Two of the animals were fed according to Fredricksen's standard, and two ad libitum. Average atmospheric conditions were 18.4°C and 65° R.H. In spring and 27.5° and 75° in summer. In spring no marked diurnal variation was evident in either ventilation rate or respiration rate, whereas in summer a well-defined cycle was evident. Tidal volume showed a distinct cycle in spring with the lower volumes occurring in the day-time, while in summer the variation was almost nil and absolute levels were lower. In both seasons the animals fed ad libitum had lower tidal volumes and a more restricted cycle. In both seasons, ventilation rates and respiration rates were not correlated with diurnal variation in climatic parameters. Ventilation rates increased by only 4% from spring to summer in both feeding groups, while respiration rate was doubled. The response of respiration rate to temperature was of the order of Q10 = 2, for changes from season to season only. In both seasons respiratory vaporization followed very similar and pronounced diurnal cycles, the maximum value being attained at 0830 hours. Higher rates were found in both seasons for the group fed ad libitum, owing mainly to consistently higher vaporization rates in the afternoon and evening hours. The diurnal cycle in vaporization was due mainly to changes in moisture content of the expired air. The partial effect of respiration rate on the moisture content of expired air and on moisture exhaled per minute was highly significant, while that of ventilation rate was not significant. The increase in absolute atmospheric humidity from spring to summer was associated with an increase in absolute humidity in the exhaled air, but this did not prevent a 12.6% reduction in respiratory vaporization.