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PubMed1997

Expired air temperature during prolonged exercise in cool- and hot-humid environments.

The purpose of this investigation was to measure expired air temperature under cool- and hot-humid environmental conditions at rest and during prolonged exercise to: (1) establish if significant increases in body core temperature affected expired air temperature, and (2) to determine if the temperature setting for heating the pneumotachometer in an open-circuit system requires adjustment during prolonged exercise tests to account for changes in expired air temperature. Six male distance runners completed two tests in cool-humid [dry bulb temperature (Tdb) 15.5 (SD 1.3) degrees C, wet bulb temperature (TWb) 12.1 (SD 1.4) degrees C] and hot-humid [Tdb 31.6 (SD 0.6) degrees C, TWb 24.9 (SD 0.6) degrees C, black globe temperature (Tg) 34.3 (SD 0.3) degrees C] environments, running at a velocity corresponding to 65% [67.1 (SD 2.82)%] of their maximal oxygen uptake. Rectal temperature and expired air temperatures were compared at rest, and after 30 min and 60 min of exercise for each environment. The main finding of this investigation was a significant (P < 0.05) but small increase in expired air temperature between the 30-min and 60-min measures in the hot-humid environment. No significant differences in expired air temperature were found between the 30-min and 60-min measures in the cool-humid environment. These findings suggest that: (1) expired air temperature is influenced by elevations in body core temperature during prolonged exercise in hot-humid conditions, and (2) that the temperature setting for heating the head of the pneumotachometer (after determining the appropriate temperature through measuring expired air temperature for the set environmental condition) may require adjustment during prolonged exercise trials in hot-humid environmental conditions.

Adult↗
PubMed1993

Air humidity: a detrimental factor in dentine adhesion.

Successful dentine adhesion may be negatively influenced by intrinsic and extrinsic dentine wetness. Testing the influence of high humidity levels during the application of bonding systems is therefore relevant. It was the aim of this study to investigate in vitro the sensitivity to air humidity of the dentine bond strength for some commercially available bonding systems. Four bonding systems were tested in vitro on human molars at temperature/humidity levels of 25 degrees C and 40% relative humidity (RH) as well as 35 degrees C and 95% RH. Four operators each made two samples of the respective treatment combinations. After shear bond testing a three-way ANOVA was carried out. Only the factors 'material', 'humidity' as well as their interaction were statistically significant. The factor 'operator' did not exert a significant influence on the shear bond strength. For the 'clinically dry' group statistically significant differences were found between all materials (P < 0.001). In the 'high humidity' setting too, significant differences were found between materials (P < 0.001). The shear bond strength values ('high humidity') were very low (< 3 MPa) for Gluma 2000, Denthesive and Syntac, while the mean values for Scotchbond Multi-Purpose were significantly higher (12 MPa; P < 0.001). It was concluded that in general bonding systems are highly sensitive to extrinsic dentine wetness, resulting in very low adhesion values at high humidity.

Acid Etching, Dental↗
PubMed2004

Effects of irrigation and air humidity preconditioning on water relations, growth and survival of Rosmarinus officinalis plants during and after transplanting.

The effect of different irrigation and air humidity conditioning treatments on the morphological and physiological responses of Rosmarinus officinalis in nursery conditions was investigated in order to evaluate the degree of hardening resulting from these conditions. Rosmarinus officinalis seedlings were pot-grown during 4 months in two greenhouses (nursery period), in which two irrigation treatments were used (control and deficit). In one of these greenhouses, air humidity was controlled using a dehumidifying system (low humidity), in the other greenhouse the air conditions were not artificially modified (control humidity). After the nursery period, the plants of all treatments were transplanted and well watered (100% water holding capacity for 1 month, transplanting period). After this period, they received no water (establishment period). At the end of the nursery period it was seen that deficit irrigation had altered the morphology of the R. officinalis plants by reducing plant height, stem diameter, leaf area, total dry weight, and root length, while humidity influenced the parameters related with plant water relations. Low air humidity and deficit irrigation-induced tissue dehydration and lower stomatal conductance values (gs). The plants subjected to deficit irrigation developed leaf osmotic adjustment, which was maintained during the transplanting period. At that time, the plants that had been exposed to deficit irrigation and low humidity showed efficient stomatal regulation (lower gs values). After transplanting and during the establishment period, these plants showed a better water status (higher psil and gs values). Their post-planting survival rate improved as a result of acclimation processes.

Humidity↗
PubMed2006

Influence of air humidity and the distance from the source on negative air ion concentration in indoor air.

Although negative air ionizer is commonly used for indoor air cleaning, few studies examine the concentration gradient of negative air ion (NAI) in indoor environments. This study investigated the concentration gradient of NAI at various relative humidities and distances form the source in indoor air. The NAI was generated by single-electrode negative electric discharge; the discharge was kept at dark discharge and 30.0 kV. The NAI concentrations were measured at various distances (10-900 cm) from the discharge electrode in order to identify the distribution of NAI in an indoor environment. The profile of NAI concentration was monitored at different relative humidities (38.1-73.6% RH) and room temperatures (25.2+/-1.4 degrees C). Experimental results indicate that the influence of relative humidity on the concentration gradient of NAI was complicated. There were four trends for the relationship between NAI concentration and relative humidity at different distances from the discharge electrode. The changes of NAI concentration with an increase in relative humidity at different distances were quite steady (10-30 cm), strongly declining (70-360 cm), approaching stability (420-450 cm) and moderately increasing (560-900 cm). Additionally, the regression analysis of NAI concentrations and distances from the discharge electrode indicated a logarithmic linear (log-linear) relationship; the distance of log-linear tendency (lambda) decreased with an increase in relative humidity such that the log-linear distance of 38.1% RH was 2.9 times that of 73.6% RH. Moreover, an empirical curve fit based on this study for the concentration gradient of NAI generated by negative electric discharge in indoor air was developed for estimating the NAI concentration at different relative humidities and distances from the source of electric discharge.

Air↗
PubMed2005

Controlled reduction of the humidity induces a shortcut recovery reaction in the photocycle of photoactive yellow protein.

The photocycle of the blue-light photoreceptor protein Photoactive Yellow Protein (PYP) was studied at reduced relative humidity (RH). Photocycle kinetics and spectra were measured in thin films of PYP in which the relative humidity was set at values between 29 and 98% RH with saturated solutions of various salts. We show that in this range, approximately 200 water molecules per PYP molecule are released from the film. As humidity decreased, photocycle transition rates changed, until at low humidity (RH < 50%) an authentic photocycle was no longer observed and the absorption spectrum of the dark, equilibrium state of PYP started to shift to 355 nm, that is, to a form resembling that of pB(dark). At moderately reduced humidity (i.e., >50% RH), an authentic photocycle is still observed, although its characteristics differ from those in solution. As humidity decreases, the rate of ground state recovery increases, while the rate of depletion of the first red-shifted intermediate pR dramatically decreases. The latter observation contrasts all so-far known modulations of the rate of the transition of the red-shifted- to the blue-shifted intermediates of PYP, which is consistently accelerated by all other modulations of the mesoscopic context of the protein. Under these same conditions, the long-lived, blue-shifted intermediate was formed not only with slower kinetics than in solution but also to a smaller extent. Global analysis of these data indicates that in this low humidity environment the photocycle can take a different route than in solution, that is, part of pG recovers directly from pR. These experiments on wild-type PYP, in combination with observations on a variant of PYP obtained by site-directed mutagenesis (the E46Q mutant protein), further document the context dependence of the photocycle transitions of PYP and are relevant for the interpretation of results obtained in both spectroscopic and diffraction studies with crystalline PYP.

Bacterial Proteins↗
PubMed2005

Rates of cuticular penetration of chelated Fe(III): role of humidity, concentration, adjuvants, temperature, and type of chelate.

Time courses of cuticular penetration of FeCl3 and Fe(III) complexes of citric acid, EDTA, EDDHA (Sequestrene 138Fe), imidodisuccinic acid (IDHA), and ligninsulfonic acid (Natrel) were studied using astomatous cuticular membranes (CMs) isolated from Populus x canescens leaves. At 100% relative humidity, the Fe(III) chelates disappeared exponentially with time from the surface of the CMs; that is, penetration was a first-order process that can be described using rate constants or half-times of penetration (t(1/2)). Half-times ranged from 20 to 30 h. At 90% humidity, penetration rates were insignificant with the exception of Natrel, for which t(1/2) amounted to 58 h. Rate constants were independent of temperature (15, 25, and 35 degrees C). Permeability decreased with increasing Fe chelate concentration (IDHA and EDTA). At 100% humidity, half-times measured with FeIDHA were 11 h (2 mmol L(-1)), 17 h (10 mmol L(-1)) and 36 h (20 mmol L(-1)), respectively. In the presence of FeEDTA, penetration of CaCl2 was slowed greatly. Half-times for penetration of CaCl2, which were 1.9 h in the absence of FeEDTA, rose to 3.12 h in the presence of an equimolar concentration of EDTA and 13.3 h when the FeEDTA concentration was doubled. Hence, Fe chelates reduced permeability of CMs to CaCl2 and to the Fe chelates themselves. It is suggested that Fe chelates reduced the size of aqueous pores. This view is supported by the fact that rate constants for calcium salts were about 5 times higher than for Fe chelates with the same molecular weights. Adding Tween 20 (5 g L(-1)) as a humectant did not increase permeability to FeIDHA at 90% humidity and below, while addition of glycine betaine did. Penetration of FeCl3 applied at 5 g L(-1) (pH 1.5) was not a first order process as rate constants decreased rapidly with time. Only 2% of the dose penetrated during the first 2 h and less than that in the subsequent 8 h. Recovery was only 70%. This was attributed to the formation of insoluble Fe hydroxide precipitates on CMs. These results explain why in the past foliar application of Fe compounds had limited success. Inorganic Fe salts are instable and phytotoxic because of low pH, while Fe chelates penetrate slowly and 100% humidity is required for significant penetration rates. Concentrations as low as reasonably possible should be used. These physical facts are expected to apply to stomatous leaf surfaces as well, but absolute rates probably depend on leaf age and plant species. High humidity in stagnant air layers may favor penetration rates across stomatous leaf surfaces when humidity in bulk air is below 100%.

Calcium↗
PubMed2003

The effect of heat and moisture exchanger on humidity and body temperature in a low-flow anaesthesia system.

BACKGROUND: Artificial humidification of dry inspired gases seems to reduce the drop in body temperature during surgery. The aim of this study was to evaluate the humidity and temperature of anaesthetic gases with heat and moisture exchangers (HMEs). The secondary aim was to evaluate if HMEs in combination with low-flow anaesthesia could prevent a decrease in the body temperature during general anaesthesia. METHODS: Ninety patients scheduled for general surgery were randomised to receive a fresh gas flow of 1.0, 3.0 or 6.0 l min-1 with or without HMEs in a circle anaesthesia system. Relative humidity, absolute humidity, temperature of inspired gases and body temperatures were measured during 120 min of anaesthesia. RESULTS: The inspiratory absolute humidity levels with HMEs were 32.7 +/- 3.1, 32.1 +/- 1.1 and 29.2 +/- 1.9 mg H2O l(-1) and 26.6 +/- 2.3, 22.6 +/- 3.0 and 13.0 +/- 2.6 mg H2O l(-1) without HMEs after 120 min of anaesthesia with 1.0, 3.0, or 6.0 l min(-1) fresh gas flows (P < 0.05, between with and without HME). The relative humidity levels with HMEs were 93.8 +/- 3.3, 92.7 +/- 2.2 and 90.7 +/- 3.5%, and without the HMEs 95.2 +/- 4.5, 86.8 +/- 8.0 and 52.8 +/- 9.8% (P < 0.05, between with and without HMEs in the 3.0 and 6.0 l min(-1) groups). The inspiratory gas temperatures with HMEs were 32.5 +/- 2.0, 32.4 +/- 0.5 and 31.0 +/- 1.9 degrees C, and 28.4 +/- 1.5, 27.1 +/- 0.8 and 26.1 +/- 0.6 degrees C without HMEs after 120 min of anaesthesia (P < 0.05, between with and without HME). The tympanic membrane temperatures at 120 min of anaesthesia were 35.8 +/- 0.6, 35.5 +/- 0.6 and 35.4 +/- 0.8 degrees C in the groups with HMEs, and 35.8 +/- 0.6, 35.3 +/- 0.7 and 35.3 +/- 0.9 degrees C in the groups without the HMEs (NS). CONCLUSIONS: The HMEs improved the inspiratory absolute humidity, relative humidity and temperature of the anaesthetic gases during different fresh gas flows. However, the HMEs were not able to prevent a body temperature drop during low-flow anaesthesia.

Adult↗
PubMedDate not supplied

Incubation of cultured skin substitutes in reduced humidity promotes cornification in vitro and stable engraftment in athymic mice.

Cultured skin substitutes have been used successfully for adjunctive treatment of excised burns and chronic skin wounds. However, limitations inherent to all models of cultured skin include deficient barrier function in vitro, and delayed keratinization after grafting in comparison to native skin autografts. Experimental conditions for incubation of skin substitutes were tested to stimulate barrier development before grafting, and measure responses in function and stability after grafting. Cultured skin substitutes consisted of human keratinocytes and fibroblasts attached to collagen-glycosaminoglycan biopolymer substrates. Parallel cultured skin substitutes were incubated at the air-liquid interface in ambient (48-61%) or saturated (79-91%) relative humidity, and grafted to athymic mice on culture day 14. Additional cultured skin substitutes were incubated in the experimental conditions for a total of 28 days. Cadaveric human skin and acellular biopolymer substrates served as controls. Epidermal barrier was evaluated as the change in surface hydration by surface electrical capacitance with the NOVA Dermal Phase Meter. Cultured skin substitutes and cadaveric skin incubated in ambient humidity had lower baseline surface electrical capacitance and less change in surface electrical capacitance than parallel samples incubated in saturated humidity at all time points in vitro. Data from healing cultured skin substitutes at 2, 4, 8 and 12 weeks after grafting showed an earlier return to hydration levels comparable to native human skin, and more stable engraftment for skin substitutes from ambient humidity. The data indicate that cultured skin substitutes in ambient humidity have lower surface electrical capacitance and greater stability in vitro, and that they reform epidermal barrier more rapidly after grafting than cultured skin substitutes in saturated humidity. These results suggest that restoration of functional epidermis by cultured skin substitutes is stimulated by incubation in reduced humidity in vitro.

Animals↗
PubMed2000

[Temperature and humidity profile of the paranasal sinuses before and after mucosal decongestion by xylometazolin].

BACKGROUND: One of the most important functions of the nose is to warm and to humidify air before it reaches the lower respiratory tract. Nasal decongestants as one of the most common drugs used in otorhinolaryngology are often associated with the feeling of a "dry nose". The purpose of this study was to determine the short-term influence of xylometazoline on temperature and humidity in the nasal airways. METHODS: 15 healthy volunteers were enclosed into the study. A miniaturised humidity sensor and thermocouple was used for detection of humidity and airway temperature in the nasal vestibule, at the nasal valve area and in the nasopharynx at the end of inspiration. Measurements were done before and after topical application of xylometazoline. RESULTS: Temperature and relative humidity increase from the anterior parts of the nose to the nasopharynx at the end of inspiration. The temperature and humidity values after nasal decongestion are not significantly different from the values before application of xylometazoline. As a tendency temperature and humidity values after nasal decongestion are even somewhat higher at the nasal valve area compared to the values before application of xylometazoline. CONCLUSIONS: Widening of the nasal airways by mucosal decongestion did not lead to a significant change of the nasal temperature and humidity profile 20-30 min after application of xylometazoline. The use of xylometazoline seems not to influence humidifying and heating of inspired air within a short period after onset of the maximal decongestive effect of xylometazoline.

Administration, Intranasal↗
PubMed1996

[New permanent humidity chamber in dry eye disorders].

BACKGROUND: In corneal lubrication or eyelid closure disorders it may be necessary to apply a monoculus to protect the eye from drying out. Changing the monoculus involves dermal irritation. Furthermore, because the monoculus is not completely airtight, the desired humidity is not achieved. INSTRUMENT: We introduce a tape-free permanent humidity chamber fastened to a spectacle frame that achieves a relative humidity of more than 98% even over a long period of time. PATIENTS/TESTED PERSONS: Five test persons and two patients with lagophthalmus were treated with a monoculus and with the permanent humidity chamber. Comparative measurements of the humidity achieved with the two methods were done. RESULTS: For both test persons and lagophthalmus patients the permanent humidity chamber is a good alternative to the monoculus, because it maintains a humidity of more than 98% r/H over a period of eight hours or longer. It consequently provides much better conditions for successful treatment and additionally minimizes skin irritation.

Dry Eye Syndromes↗
PubMed1995

The effect of relative humidity on mouse allergen levels in an environmentally controlled mouse room.

To determine the effect of humidity on the levels of the mouse allergen Mus m 1, an experimental animal room was constructed to control environmental variables. The sex, strain, age, and number of mice was constant in the room, so that the average daily production of Mus m 1 would not vary greatly. Six different levels of relative humidity from 15% to 65% were maintained for a minimum of a week each. Daily collections of airborne particulates were eluted from filters and Mus m 1 content measured by immunological assay. Increasing relative humidity caused a decrease in Mus m 1 levels from a high of 3 ng/m3 at 15% humidity to a low of 0.5 ng/m3 at 65% humidity. Thus, reduction of airborne allergen levels can be achieved by careful attention to humidity control, especially during the winter heating season when humidity levels may be low. This experimental room can be used to measure the effect of other variables such as ventilation rate, caging, bedding, and work practices on the levels of mouse allergen in an animal facility.

Allergens↗
PubMed2004

Influences of calcium oxide content in marine fuel oil on emission characteristics of marine furnaces under varying humidity and temperature of the inlet air.

A marine furnace made of stainless steel. combined with an automatic small-size oil-fired burner, was used to experimentally investigate the influences of calcium oxide content in fuel oil on the combustion and emission characteristics under varying temperatures and humidity of the inlet air. Marine fuel oil generally contains various extents of metallic oxides such as CaO, Fe2O3, V2O5, etc which might affect its burning properties. In this study, an air-conditioner was used to adjust the humidity and temperatures of the inlet air to preset values prior to entering the burner. The adjusted inlet air atomized the marine diesel oil A containing a calcium oxide compound, to form a heterogeneous reactant mixture. The reactant mixture was thereafter ignited by a high-voltage electrode in the burner and burned within the marine furnace. The probes of a gas analyzer, H2S analyzer and a K-type thermocouple were inserted into the radial positions of the furnace through the eight rectangular slots which were cut in the upper side of the furnace. The experimental results showed that an increase of either humidity or temperature of the inlet air caused the promotion of the reaction rate of the fuel. The existence of calcium oxide compound in the diesel fuel also facilitated the oxidation reaction in the combustion chamber. The addition of CaO in the diesel fuel under the conditions of higher temperature or higher relative humidity of the inlet air produced the following: higher concentrations of CO2, SO2, and H2S emissions, an increased burning efficiency, a lowered O2 level, production of excess air and NOx emissions as well as a lower thermal loss and a lower burning gas temperature, as compared with the conditions of a lower temperature or a lower humidity of the inlet air. In addition, the burning of diesel fuel with added CaO compound caused a large variation in the burning efficiency, thermal loss, plus CO2, O2, and excess air emissions between the conditions of higher temperature/higher humidity and lower temperature/lower humidity inlet air compared with no CaO addition in the fuel. Moreover, the burning efficiency and the concentrations of excess air and O2 emissions increased, while the thermal loss, burning gas temperature and H2S, SO2, NOx, and CO2 emissions decreased with the increase of the axial distance from the measured location to the burner nozzle.

Air Movements↗
PubMed2005

Thermoregulation responses of broiler chickens to humidity at different ambient temperatures. II. Four weeks of age.

Two experiments were conducted to investigate the effect of RH (35, 60, and 85%) on thermoregulation of broiler chickens at high (35 degrees C) and mild (30 degrees C) temperatures at the age of 4 wk. The effects of humidity on rectal temperature (RT) and plumage temperature at back (PBAT) and skin temperature at breast (SBRT) were determined at 1, 4, 8, 16, and 24 h after exposure. The RT, PBAT, and SBRT were all significantly increased by high temperature (35 degrees C). Humidity had a significant influence on RT at 35 degrees C but not at 30 degrees C. The peripheral temperatures (PBAT and SBRT) were significantly affected by humidity but responded differently at high (35 degrees C) compared with mild temperature (30 degrees C). In conclusion, high humidity above 60% impaired the heat transmission from body core to the periphery at 35 degrees C but facilitated it at 30 degrees C in 4-wk-old broiler chickens. The effect of humidity on nonevaporative heat loss was depended on air temperature, as nonevaporative heat loss was suppressed by high humidity (>60% RH) at high temperature but enhanced at the mild temperature. The effect of humidity on the relationship between peripheral and core temperature depends on ambient temperature as well as on the age of the broiler chicken. The disturbance of thermal balance could not be determined only by changes in RT or peripheral temperature at a single time point but could be determined by mean body temperature within a certain time frame.

Aging↗
PubMed1991

Is neonatal inspired gas humidity accurately controlled by humidifier temperature?

OBJECTIVE: To investigate: a) the relationship between humidifier temperature and inspired gas humidity and b) the effect of insulating the inspiratory tube on "rainout" (condensate). DESIGN: Observational study. SETTING: Regional neonatal unit in a university hospital. PATIENTS: Forty-eight infants receiving assisted ventilation, of whom 31 infants were nursed in incubators and 17 under radiant heaters. MEASUREMENTS AND MAIN RESULTS: Despite always maintaining humidifier temperature greater than 34.7 degrees C, inspired gas humidity decreased below the American National Standards Institution minimum of 30 mg H2O/L on 35 of 479 occasions. At a humidifier temperature of 36 degrees C, inspired gas humidity varied between 17 and 43 mg H2O/L. In incubators set at a temperature of 34.1 +/- 1.3 (SD) degrees C, inspired gas humidity was linearly related to humidifier temperature, but with wide scatter (p less than .001, r2 = .28). In cooler incubators set at 32.9 +/- 1.8 degrees C, inspired gas humidity varied inversely with humidifier temperature. This variation was attributed to condensate due to inspired gas cooling within the incubator. Insulation of the inspiratory tubing reduced condensate by only 15%. CONCLUSIONS: Inspired gas humidity cannot be predicted reliably from humidifier temperature. Accurate control will require a new generation of humidifiers that measure inspired gas humidity.

Equipment Design↗
PubMed2002

Temperature and humidity consideration for calculating airborne 222Rn using activated charcoal canisters.

A radon calibration chamber with variable and controlled radon concentration, humidity, and temperature was constructed and used to extend the calibration range of open-faced and diffusion-barrier charcoal canisters for higher temperature and humidity applications. The optimum exposure time to achieve the best detection accuracy and the lowest minimum detectable level was between 2 and 4 d depending on relative humidity for open-faced canister and 4 d for diffusion barrier canister over a range of humidity. The dependence of radon adsorption on the temperature was also studied for both types of canister at different values of relative humidity. The open-faced canisters at 15 degrees C absorb 68% more radon than at 30 degrees C over the range of humidity from 20% to 80%. The diffusion-barrier canister shows insignificant variation in absorption over the same range of temperature and humidity.

Air↗
PubMed2005

The temperature and humidity of inspired gases in infants using a pediatric circle system: effects of high and low-flow anesthesia.

BACKGROUND: The effects of low-flow anesthesia on the temperature and humidity of the inspired gas in infants during mechanical ventilation is unknown. This study was designed to evaluate the temperature and humidity of the inspired gas in infants using a pediatric circle absorber system with high and low fresh gas flow (HFGF and LFGF) anesthesia. METHODS: Twenty infants participated in this observational, sequential, cross-over study. Each infant was mechanically ventilated with a Kion Anesthesia Workstation, using a pediatric anesthesia circle circuit with both HFGF (6 l.min(-1)) and LFGF (0.6 l.min(-1)) technique. Airway temperature was recorded continuously at 16 sites throughout the breathing circuit. The relative humidity of the inspired gas was measured at the elbow connector adjacent to the CO2 sampling line. RESULTS: The mean airway temperatures of the inspired gas and the changes in mean airway temperatures throughout the breathing circuit during HFGF and LFGF did not differ significantly. The mean relative humidity of the inspired gas at steady state using a LFGF technique, 33.7 +/- 3.6%, was approximately threefold greater than it was with a HFGF technique, 11.9 +/- 5.1% (P < 0.05). CONCLUSIONS: Low-flow anesthesia with a pediatric circle system in infants neither increases the temperature of the inspired gas, nor achieves the minimum humidity of 50% reported to prevent ciliary damage, although the humidity during LFGF did increase threefold compared with HFGF. To maintain the temperature and humidity of the inspired gas during mechanical ventilation in infants, passive or active gas humidification should be used.

Anesthesia, Inhalation↗
PubMed1999

Impact of temperature and humidity on chemical and sensory emissions from building materials.

The chemical and sensory emissions from five building materials (carpet, polyvinyl chloride (PVC) flooring, sealant, floor varnish and wall paint) were tested under different combinations of temperature and relative humidity in the ranges 18-28 degrees C and 30-70% relative humidity (RH). The experiment was performed in a climate chamber where a specially designed test system was built to study emissions from the five materials. The test system could provide different temperatures and humidities of air around the materials, while the air, after being polluted by the emissions from the materials, could be reconditioned to 23 degrees C and 50% RH for sensory assessments. The experiment was designed to separate the direct impact of temperature and humidity on perception from the impact on sensory emission. The study found little influence of temperature on the emissions from the five materials whether expressed in chemical or sensory terms. The effect of humidity was found to be significant only for the waterborne materials--floor varnish and wall paint. Compared with the direct impact of temperature and humidity on the perception of air quality, the impact of temperature and humidity on sensory emissions from the building materials has a secondary influence on perceived air quality.

Adult↗
PubMed1991

Tracheal vascular and smooth muscle responses to air temperature and humidity in dogs.

Twenty-five dogs were anesthetized, paralyzed, and artificially ventilated. Their cranial tracheal arteries were perfused bilaterally with blood at constant flow, and the perfusion pressures (Patr) were measured. Tracheal smooth muscle function was assessed by recording changes in external diameter (delta Dtr). The perfused segment of the trachea was exposed to air at a constant unidirectional airflow of 25 l/min. Group 1 (n = 6) was exposed to cold dry air, ambient room air, and hot dry and hot humid air, each for 10 min with exposures starting from zero flow. The tracheal vascular responses to all four conditions were small vasodilations (delta Patr from -2 to -6%) followed by recovery or small vasoconstrictions. In group 2 (n = 19), exposures to cold dry and hot humid air were preceded and followed by body-temperature fully humidified air. Cold dry air caused a sustained vasodilation (delta Patr -9.0 +/- 1.1%), and hot humid air usually caused a biphasic response: a vasoconstriction (delta Patr 4.4 +/- 1.0%) followed by a vasodilation (delta Patr -5.7 +/- 1.9%). The warm humid air after cold dry air or hot humid air caused a further vasodilation, which lasted a short time after cold dry air (delta Patr -3.7 +/- 0.4%) but greater than 10 min after hot humid air (delta Patr -13.8 +/- 1.4%). In both groups, all exposures that cooled the trachea (cold dry air, ambient room air, and hot dry air) caused smooth muscle contraction, and hot humid air that warmed the trachea caused relaxation.

Animals↗