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PubMed2003

The vulva skin microclimate: influence of panty liners on temperature, humidity and pH.

Many women use panty liners between menstrual periods. The aim of this study was to investigate whether the use of such products might influence the vulva skin. Twelve healthy women were studied on four occasions with three different product constructions and on one occasion without products. Temperature, surface wetness and surface pH were measured on vulva skin. Mean skin temperature when the women were wearing a conventional panty liner (with a non-breathable back sheet) was 35.9 degrees C, compared to 34.4 degrees C when wearing no panty liner at all (p < 0.01) and 34.5 degrees C when using a panty liner with a breathable (i.e. vapour permeable) back sheet (p < 0.01). Skin humidity was significantly higher when the conventional panty liner was used compared to no panty liner or to the breathable panty liner (both cases p < 0.01). The mean pH value at the exterior aspect of the labium majus was 5.8 with the conventional panty liner, 5.2 with no panty liner and 5.3 with the breathable panty liner (p < 0.001 and p < 0.01, respectively). The results indicate that the conventional panty liner changes the vulva skin microclimate, but that the breathable panty liner to a substantial degree keeps the microclimate at an undisturbed level. The actual effect of these differences on microbiological flora will be addressed in a subsequent study.

Adult↗

PubMed1977

Use of detector tubes under extreme conditions (humidity, pressure, temperature).

Detector tubes are mainly used in a temperature range between 0 degrees C and 40 degrees. At lower temperatures systematic minus indications may occur, high temperatures cause plus indications. By utilizing simple warming-up methods or cooling devices the temperature of the gas to be tested can be adjusted to a temperature which which is suitable for detector tubes. Humidity often influences chemical reagents. In detector tubes this interfering effect can be eliminated by special drying preparations. The reading of most of the detector tubes is directly proportional to the absolute air pressure. Pressure correction can be done easily by the gas law.

Air Pressure↗

PubMedDate not supplied

Effect of relative humidity on the adsorption of selected water-miscible organic vapors by activated carbon.

The adsorptive capacity of activated charcoal was determined experimentally for the vapors of 2-ethoxyethanol, pyridine, acetic acid, and piperidine from dry air and from air saturated with water vapor. Vapor concentrations ranged from 100 mg/m3 to at least 1000 mg/m3; the temperature was kept constant at 25 degrees C. The reduction in the adsorptive capacity of the activated charcoal by the relative humidity over the entire range of experimental conditions was accounted for by the Hansen-Fackler modification of the Dubinin-Radushkevich equation. This procedure allows the use of the activity coefficients, which are basic thermodynamic factors often available in the literature, to estimate the effect of adsorbed moisture on the adsorption of these organic compounds from a humidified atmosphere.

Acetic Acid↗

PubMed2000

Relative humidity at moderate ambient temperatures: its effect on male broiler chickens and turkeys.

1. The effect of relative humidity (RH, 40% to 75%) at moderate ambient temperatures (Ta, 28 degrees and 30 degrees C) on the performance and thermoregulation of male broiler chickens and turkeys was studied at the age of 4 to 8 weeks. 2. Weight gain and food intake of male broiler chickens were significantly higher at 60% to 65% RH but food conversion efficiency was not affected by RH. In male turkeys, no effect of RH on performance was recorded. 3. Both chickens and turkeys controlled body temperature at normothermic levels during exposure to the experimental environmental conditions. 4. The rate of panting estimated from blood pH and pCO2 was lower in chickens exposed to 28 degrees C than to 30 degrees C. In turkeys, the rate was lower than that recorded in chickens at both Ta(s). 5. Plasma T3 was positively and significantly correlated with food intake. 6. It may be concluded that RH plays a role in the performance of chickens exposed to 30 degrees and 28 degrees C. whereas male turkeys must respond to RH at Ta >30 degrees C.

Animals↗

PubMed2003

Environmental and human factors influencing thermal comfort of office occupants in hot - humid and hot - arid climates.

The effects of environmental and individual factors on thermal sensation in air-conditioned office environments were analysed for two large, fully compatible thermal comfort field studies in contrasting Australian climates. In the hot - humid location of Townsville, 836 office workers were surveyed; 935 workers participated in hot - arid Kalgoorlie-Boulder. Overall perceived work area temperature and measured indoor operative temperature correlated moderately with thermal sensation for Townsville (T) subjects but only perceived temperature correlated with Kalgoorlie-Boulder (KB) sensation. Multiple regression analyses confirmed that indoor climatic variables (including Predicted Mean Vote) contributed to actual thermal sensation vote (24% T; 15% KB), with operative temperature having more of an effect in T than in KB. Subsequent analyses of individual characteristics showed no linear contributions to thermal sensation. The remaining variances were significantly related to perceived work area temperature (7% additional explained variance in T; 12% in KB). Mann - Whitney analyses (after correction for climatic variables) showed that T subjects with higher job satisfaction had thermal sensations closer to 'neutral'. Males, healthier subjects, non-smokers, respondents with earlier survey times and underweight occupants had lower median thermal sensations in KB. Townsville occupants appeared more adapted to their outdoor climatic conditions than Kalgoorlie-Boulder respondents, perhaps due to limited home air-conditioning. Further research into non-thermal impacts on gender-related thermal acceptability is suggested.

Adolescent↗

PubMed1993

Physiological strains in hot-humid conditions while wearing disposable protective clothing commonly used by the asbestos removal industry.

The purpose of this study is to investigate workers' responses to work in hot-humid conditions while wearing protective clothing commonly used by the asbestos removal industry, and to evaluate the effects of resting between work bouts in a cool environment on the physiological strain. Seven male students wearing impermeable protective clothing and air masks were exposed to the following conditions for 100 min on separate days: (1) hot conditions (35 degrees C/85%RH), (2) cool conditions (20 degrees C/85%RH), and (3) hot/cool conditions (working in hot conditions and resting in cool conditions). After 12 min rest, the subjects worked on an ergometer (70 Watts) for 18 min. This experimental schedule was repeated three times under each environmental condition. Rectal temperature (Tre), heart rate (HR), sweat rate (SR) and discomfort sensation were recorded. Two of the subjects were not able to complete the experiment in hot conditions. The increases in Tre and HR with time were not found in cool conditions. Although Tre increased in hot/cool conditions, it was almost half of that in hot conditions. Since HR did not return to the pre-work level during recovery in hot conditions, HR during work was accompanied by increases in HR at pre-work. HR during work in hot/cool conditions was higher than that in cool conditions, HR at pre-work, however, was almost the same as that in cool conditions because of rapid recovery. The means of SR in hot and hot/cool conditions were five and four times greater than that in cool conditions, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1995

Clothing, assessment and effects on thermophysiological responses of man working in humid heat.

This paper presents the relative importance of the different factors to be taken into account when predicting thermal exchanges when man is wearing garments while being exposed to warm environments. Factors considered are the thermal insulation of clothing (CLO), the thermal efficiency of clothing (Fcl), the clothing area factor (fcl), the pumping coefficient (p), the vapour permeation efficiency factor (Fpcl). As Fpcl depends on CLO, Fcl,fcl and p factors, physiological assessments of this factor appears to be necessary for the calculation of the maximum evaporative capacity (Emax) in clothed subjects. In this paper, comparisons of body temperatures, whole body and local sweating were made from data obtained on both unclothed and then clothed subjects working at 50 watts on a cycloergometer in warm environments (Ta = Tr = Tsk), with increasing ambient humidity levels (Pa). Results showed that clothed subjects sweated more than unclothed man for the same Pa increases and hidromeiosis occurring on the skin of unclothed man seemed to be responsible for this. Sweat accumulation in the clothes confirms that the decrease in the evaporative sweat efficiency for clothed subjects was closely associated with the threshold for occurrence of core temperature drift. However the less important slope in the Tcore vs delta Pa relationship for clothed subjects compared to that for unclothed implies a more efficient body cooling thanks to clothing, which does not lead to as great a physiological disadvantage as expected. Pumping effect and additional concurrent evaporation could account for this phenomenon: the ISO model (Required sweat rate) which includes an additional air velocity as a function of metabolism allows us to consider this beneficial influence of increased Emax in clothed subjects. However this effect should not be considered when the model is used for unclothed subjects.

Adult↗

PubMed2006

Direct field observation of the relative humidity effect on the beta-gauge readings.

The effect of ambient relative humidity (RH) on hourly particulate matter (PM10) readings of beta-gauge monitors has been studied using two collocated monitors in the field. The inlet air of monitor 1 was conditioned with water vapor to increase its RH, whereas monitor 2 operated normally in ambient conditions. Experimental data showed that PM10 readings of monitor 1 were nearly the same as monitor 2, as long as the RH of its conditioned incoming air did not exceed approximately 80-85%. However, when the RH exceeded approximately 80-85%, PM10 readings of monitor 1 became higher than monitor 2, and the difference increased with increasing RH. The measurement of pressure drop across the filter was also conducted, and the data revealed that the increase of pressure drop per unit of PM10 concentration decreased when RH was higher than approximately 80-85%, as compared with the case when RH was lower than 80-85%. This is perhaps because of more porous structure of deposited particles in the beta-gauge monitor when RH is greater than approximately 80-85%. The theoretical calculation using an evaporation model and a thermodynamic model has been conducted to simulate the beta-gauge readings. The results show that the theoretical PM10 concentrations using the evaporation model are in better agreement with the actual beta-gauge readings than those using the thermodynamic equilibrium model.

Air Pollutants↗

PubMed1999

An analysis of work environments and operations in hot and humid areas.

Crews on tankers traveling and hauling cargo on the lower reaches of the Mississippi River during the hot and humid (H&H) summer season face various occupational safety and ergonomics problems. Evaluation of medical data reveals that a large number of the crewmembers experience job related injuries, diseases, disorders, and exhaustion as a result of adverse environmental conditions (National Institute for Occupational Safety and Health [NIOSH], 1993). The accidents and injuries that occurred were characterized and then analysis was used to recommend constructive remedies and solutions. The results were also used to design and develop better work environments on the tankers and in the general industry. In H&H conditions, the body's chemical reactions constantly change in order to maintain the best possible reaction to changing environments. This chemical reaction increases blood flow to the skin through sweating. Body metabolism stabilizes body temperature through muscular work and convection, evaporation and radiation remove heat.

Body Temperature↗

PubMed2006

Test of firefighter's turnout gear in hot and humid air exposure.

Five students of a rescue training school cycled at 50 W for 20 min at 20 degrees C before walking at 5 km/hr up to 30 min in a climatic chamber at 55 degrees C and 30% relative humidity. 4 different types of clothing ensembles differing in terms of thickness and thermal insulation value were tested on separate days. All subjects completed 28-30 min in light clothing, but quit after 20-27 min in 3 firefighter ensembles due to a rectal temperature of 39.0 degrees C or subjective fatigue. No difference in the evolution of mean skin or rectal temperature was seen for the 3 turnout ensembles. Sweat production amounted to about 1000 g in the turnout gears of which less than 20% evaporated. It was concluded that the small differences between the turnout gears in terms of design, thickness and insulation value had no effect on the resulting heat physiological strain for the given experimental conditions.

Adult↗

PubMedDate not supplied

The influence of humidity on the overall mass transfer coefficient of the Wheeler-Jonas equation.

The Wheeler-Jonas model is well known for its good prediction of breakthrough times for organic vapors on activated carbon beds. However, it is valid only in dry conditions: no prewetting of the filter and no humidity in the ambient air during use. One of the parameters that is likely to be influenced is the overall mass transfer coefficient kv. By measuring over 200 breakthrough times, with 7 different vapors on 4 different types of activated carbon, a simple but satisfactory model for the influence of moisture on kv was established. The only items of information needed, compared with the application of the Wheeler-Jonas equation under dry circumstances, are the water isotherm and the total pore volume of the activated carbon.

Adsorption↗

PubMed1985

Comparison of solid sampling media for Aroclor 1254 vapor under dry and humid conditions.

Chromosorb 102 (60/80 mesh) was as good a sampling sorbent for Aroclor 1254 vapor as deactivated Florisil (30/60 mesh), but recoveries were less precise when vapor collection occurred at 90% relative humidity. Tenax-GC (35/60 mesh) and XAD-2 (20/60 mesh) are probably also acceptable based on spiking experiments. The phenomenon of vapor phase enrichment of the most volatile PCBs in Aroclor 1254 was noted and was allowed for by the Webb-McCall method of quantitation. An inexpensive generator of PCB vapor to produce a 300 micrograms/m3 volatilization rate over a two-week period also was developed.

Air Pollutants, Occupational↗

PubMed2000

Lack of response of laying hens to relative humidity at high ambient temperature.

1. The effects of relative humidity (rh=40% to 70%) at high ambient temperature (Ta) on the performance of laying hens at different ages (8 to 10 months, Trial 1; and 16 to 18 months, Trial 2) was evaluated. Laying hens were exposed to 25 degrees C (control) for 3 weeks and thereafter acclimated for 1 week to 35 degrees C and 4 different rh. 2. Body weight declined significantly in young and older hens exposed to 60% or 70% and 70% rh, respectively: Food intake declined with increasing Ta, except in the case of older hens exposed to 60% rh, for which it remained relatively constant. Water consumption, however, increased with increasing Ta but the increase was significant in young hens exposed to 70% rh only. 3. Egg production was not affected by the changes in Ta. However, a decrease in egg production was observed in older hens exposed to 60% rh. 4. Egg weight (EW), shell weight (SW) and shell thickness (ST) were significantly reduced by exposure to elevated Ta, whereas % breakage significantly increased. In young hens, a response to rh was exhibited in ST which was significantly higher in hens exposed to the low rh (40% to 45%) than in those exposed to the highest rh (70% to 75%). 5. It can be concluded that Ta is the main environmental factor affecting young and older laying hens while the effect of rh is minor.

Age Factors↗

PubMed1978

Effect of physical activity on human potassium metabolism in a hot and humid environment.

Previous investigations have suggested that there are high potassium losses during heavy physical activities in hot climates. In order to determine if high levels of potassium losses could be offset by potassium loading, this study was conducted with five long-distance track runners who had trained in hot and humid environments. The liquid supplements containing 4.3, 98.0, and 0.0 mEq/liter of potassium were given 1 to 2 hr before physical activity. The daily diet contained 2.6 g of potassium. A sodium and potassium balance study was conducted in which stool, urine, and dermal losses were measured. In order to determine if there was a change in the distribution of body potassium during physical exercise, seven subjects total body potassium was estimated before and after exercise. This measurement was performed by counting 40K in a whole body counter. Although the subjects with potassium supplementation and higher urinary sodium and potassium losses, the 98 mEq/liter of potassium supplement resulted in a positive potassium balance. The subjects' potassium requirements exceeded the National Research Council suggested dietary intake. The total body potassium measurements indicated that the counting efficiency of 40K increases significantly immediately after the period of vigorous exercise.

Adult↗

PubMed2005

Effect of canopy position on germination and seedling survival of epiphytic bromeliads in a Mexican humid montane forest.

BACKGROUND AND AIMS: Seeds of epiphytes must land on branches with suitable substrates and microclimates to germinate and for the resulting seedlings to survive. It is important to understand the fate of seeds and seedlings in order to model populations, but this is often neglected when only established plants are included in analyses. METHODS: The seeds of five bromeliad species were exposed to different canopy positions in a Mexican montane forest, and germination and early seedling survival were recorded. Additionally, the survival of naturally dispersed seedlings was monitored in a census over 2.5 years. Survival analysis, a procedure rarely used in plant ecology, was used to study the influence of branch characteristics and light on germination and seedling survival in natural and experimental populations. KEY RESULTS: Experimental germination percentages ranged from 7.2 % in Tillandsia deppeana to 33.7 % in T. juncea, but the seeds of T. multicaulis largely failed to germinate. Twenty months after exposure between 3.5 and 9.4 % of the seedlings were still alive. There was no evidence that canopy position affected the probability of germination, but time to germination was shorter in less exposed canopy positions indicating that higher humidity accelerates germination. More experimental seedlings survived when canopy openness was high, whereas survival in census-seedlings was influenced by moss cover. While mortality decreased steadily with age in juveniles of the atmospheric Tillandsia, in the more mesomorphic Catopsis sessiliflora mortality increased dramatically in the dry season. CONCLUSIONS: Seedling mortality, rather than the failure to germinate, accounts for the differential distribution of epiphytes within the canopy studied. With few safe sites to germinate and high seedling mortality, changes of local climate may affect epiphyte populations primarily through their seedling stage.

Environment↗

PubMed1983

Influence of temperature and relative humidity on human rotavirus infection in Japan.

A climatologic analysis of human rotavirus infection in inpatients with acute diarrhea was conducted over a seven-year period. The infection frequency appeared to be related to temperature, but not to relative humidity. Human rotavirus infection was found to appear abruptly when the mean temperature of any 10-day period became less than 5 C (November or December), reached a peak when it was less than 0 C (January and February), and waned when it became greater than 20 C (June and July) in the city of Yamagata in northern Japan.

Adolescent↗

PubMed1998

Survival, fecundity, and development of Dermatophagoides farinae (Acari: Pyroglyphidae) at fluctuating relative humidity.

We determined the survival, development, and fecundity of Dermatophagoides farinae Hughes exposed to fluctuating daily regimes of hydrating and dehydrating relative humidity. Larva emerged from 84, 92, and 94% of eggs incubated at a regime of 2, 4, and 8 h at 75% RH and 22, 20, and 16 h at 0% RH, respectively. No emerging offspring completed the life cycle when exposed to the 2 and 4 h of moist air daily but 44 and 53% survived for 70 d in the larval or nymphal stages, respectivley, and these completed development to adults when subsequently held at a constant 75% RH. Given 8 h of moist air daily, 41% of emerging offspring completed the life cycle but development was 1.6 times longer compared with development at a constant 75% RH. For all daily hydrating and dehydrating regimes, a greater percentage of offspring became males than females. Overall, survival of immatures was remarkable at these daily long periods of dehydrating conditions when a short period of hydrating moisture was provided. When exposed to a daily regime of 4 h of moist air (75% RH) and 20 h of dry air (0% RH), 84% of females survived 28 d and produced approximately 1/3 of the number of eggs produced at constant 75% RH (control).

Animals↗

PubMed2005

Development of Dermatophagoides pteronyssinus (Acari: Pyroglyphidae) at constant and simultaneously fluctuating temperature and humidity conditions.

House dust mites are found in almost all dwellings in New Zealand and are a major risk factor in the development of asthma and perennial allergic rhinitis. We studied the longevity, life stage length, and fecundity of a New Zealand strain of European house dust mite, Dermatophagoides pteronyssinus (Trouessart), at constant (23 degrees C, 75% RH) and the fluctuating conditions typically found in dry (18-25 degrees C, 60-38% RH) and damp (18-23 degrees C, 70-55% RH) New Zealand dust mite microhabitats in carpets. All the adult mites placed in the "dry" conditions died within 18 d. Mites in the "da conditions had developmental times, oviposition, and death rates that were not significantly different from constant conditions. These mites are tolerant of fluctuating temperatures, but they are more susceptible to environments that strongly fluctuate in humidity.

Animals↗