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PubMed1997

The effect of relative humidity of inhaled air on acoustic parameters of voice in normal subjects.

The hypothesis that relative humidity (RH) of air exerts an effect on voice has been widely accepted. The aim of this study has been to assess whether this can be demonstrated. Eight healthy subjects inhaled during ten minutes three different air conditions: dry, standard room, and humidified air. After inhalation, the subjects produced repeatedly a sustained /a/ of controlled pitch and loudness, which was analyzed for perturbation and noise-to-harmonic parameters. Perturbation measures increased after inhalation of dry air. No significant differences existed between standard and humidified air. No significant difference in the noise-to-harmonic ratio was found among the three conditions. We conclude that the human voice is very sensitive to decreases in RH of inhaled air, because even after a short provocation with dry air, a significant increase in perturbation measures was found.

Adult↗
PubMedDate not supplied

Quantitative noise analysis in a modern hospital.

Quantitative noise analysis of a general surgical ward in a modern hospital showed that the level of noise was in excess of recommended levels and of sufficient intensity to disturb sleep. Individual noises in excess of 50 dB(A) were recorded in every area at all times of the day. Internal hospital sounds were responsible for most noise; staff and audible warning devices were the main sources of noise over 70 dB(A). Octave waveband analysis showed that both the general ward noise and the noise of the air conditioning were in excess of recommended levels.

Air Conditioning↗
PubMed1992

Economic humidity control: an alternative to reheat.

Heat pipe technology will have a significant impact on the power consumption of many manufacturing industries, the installation costs of new or replacement air conditioning systems, and on electric utility peak demands.

Air Conditioning↗
PubMedDate not supplied

Role of ventilation in the causation of building-associated illnesses.

The objective of this article is to provide the reader with a basic knowledge of the operation of heating, ventilation, and air-conditioning (HVAC) systems and to explain why many systems do not perform correctly. The flow of air through a typical HVAC system is described, and the correlation between system components and their potential to affect indoor air quality is addressed.

Air Conditioning↗
PubMed1980

Environmental quality within animal facilities.

Maintenance of environmental quality for laboratory animals involves more than heat and moisture production of animals or room air changes per hour. Heating, ventilating and air conditioning of animal facilities allows control of room temperature and humidity, cage microenvironment, gaseous and particulate contamination, air distribution and diffusion, air quality and temperature differentials. However, other factors may influence environmental quality: population density, species of animals, and husbandry and sanitation practices. Because of all of these considerations, animal facilities tend to be energy intensive. Recommended environmental conditions are designed to satisfy physiological requirements of animals but prevent physiologic and psychophysiologic stresses. Analytical studies will provide necessary information to attain these goals and simultaneously reduce energy expenditures or minimize the need for expensive control systems.

Air Conditioning↗
PubMed1985

Indoor infection in a modern building.

Outbreaks of tuberculosis (TB), which are of a type rarely experienced in the past, have recently increased in Japan. An example of such an outbreak, which occurred in a modern building with fixed sash windows, will be described. The occurrence of four TB cases, which had been found during the period between May 1979 and June 1980 among company employees working in the same building in downtown Tokyo, motivated the conduct of epidemiological and environmental surveys on this episode. The first case, a 36-year-old male with a positive smear and cavities in both lungs, was considered to have been in an infectious state for about one year before his admission to a TB hospital in June 1979. Follow-up investigation of 99 contacts until March 1982 revealed the occurrence of 16 secondary cases. The secondary attack rate was highest among those working on the same floor of the building as this first case, but no case was found among employees of another company that occupied this building. The desks of secondary cases were aggregated near and around that of the first case. Although this building had central air-conditioning, ventilation was often closed for energy conservation purposes. This resulted in the increase of carbon dioxide concentration in the air up to a level of more than 1,000 ppm during working hours and to as high as 2,000 ppm when the ventilation was closed. It was thus concluded that the indoor infection of TB in this episode was attributable to the insufficient ventilation in the building.

Adult↗
PubMed1990

Effects of humid air breathing during arm or treadmill exercise on exercise-induced bronchoconstriction and refractoriness.

Although it has been reported that inhibitory prostaglandins may be a causal factor in exercise refractoriness, it is still unclear whether exercise-induced bronchoconstriction (EIB) and/or other specific "exercise factors" are necessary to trigger their release and render a subject refractory to subsequent exercise. The purpose of this study was to determine whether non-EIB-producing exercise with the legs or arms could produce refractoriness to a standard treadmill challenge. Eight asthmatic subjects with EIB completed three sessions consisting of two exercise challenges separated by a 30-min rest. In all sessions, the second challenge was done on a treadmill while breathing dry air. Conditions for Challenge 1 were the following: Session A = treadmill, dry air; Session B = treadmill, humid air; Session C = arm cranking, humid air. All three conditions produced a significant degree of refractoriness. There was a tendency for the percent protection index to be greater for Session A; however, no significant differences were found among the three sessions. Therefore, it can be concluded that although both exercise and bronchoconstriction may play a role in producing the refractory period, neither severe bronchoconstriction nor intense exercise with the same muscle groups are required to produce refractoriness.

Adult↗
PubMed1996

[Aspergillus lung pathology in transplant patients].

Invasive pulmonary aspergillosis, with or without dissemination to other organs, is a severe complication in patients who have undergone transplantation. The incidence of this disease is conditioned by the type of transplantation, the intensity of immunosuppressive regimens, and local epidemiology. The latter factor underscores the importance of air conditioning systems, and special caution is needed in case of hospital renovation. The clinical picture is frequently characterized by persisting fever, despite antibiotic treatments, but is otherwise non specific. Computerized tomography and magnetic resonance imaging show typical lesions more often than do conventional chest x-ray films. The sensitivity of broncho-alveolar lavage is poor, and DNA amplification techniques for Aspergillus might increase the diagnostic yield in the future. Also, detection of Aspergillus antigens in serum and urine might prove useful, but further studies are needed before a standardized test can be recommended for diagnostic purpose. Intravenous amphotericin B is the treatment of choice. Liposomal and other lipid formulations of this drug represent interesting alternatives, although very expensive. Itraconazole is emerging as a promising drug, because of fewer side effects than amphotericin. However, improvement of its formulation is still necessary.

Air Conditioning↗
PubMed1985

Operant control of convective cooling and microwave irradiation by the squirrel monkey.

Adult male squirrel monkeys (Saimiri sciureus) were individually chair-restrained in an air-conditioned Styrofoam box in the far field of a horn antenna. Each monkey first received extensive training to regulate the temperature of the air circulating through the box by selecting between 10 and 50 degrees C air source temperatures. Then, to investigate the ability of the animals to utilize microwaves as a source of thermalizing energy, 2450-MHz continuous wave microwaves accompanied by thermoneutral (30 degrees C) air were substituted for the 50 degrees C air. Irradiation at each of three power densities was made available, ie, at 20, 25, and 30 mW/cm2 [SAR = 0.15 (W/kg)/(mW/cm2)]. The percentage of time that the monkeys selected microwave irradiation paired with thermoneutral air averaged 90% at 20 and at 25 mW/cm2. The mean percentage declined reliably (p less than 0.001) to 81% at 30 mW/cm2, confirming the monkey's ability to utilize microwave irradiation as a source of thermal energy during the course of behavioral thermoregulation. All animals readily made the warm-air to microwave-field transition, regulating rectal temperature with precision by sequentially selecting 10 degrees C air, then microwave irradiation accompanied by 30 degrees C air. Although the selection of cooler air resulted in a slight reduction of skin temperatures, normal rectal temperature was maintained. The results indicate that the squirrel monkey can utilize a microwave source in conjunction with convective cooling to regulate body temperature behaviorally.

Air Conditioning↗
PubMed1976

Heat illness. III. Acclimatization.

In this third paper on heat illness, the position of acclimatization in prevention of heat illness is reviewed. Both short and long-term acclimatization are considered, the former in more detail with discussion of present knowledge of the differences arising from artificial and natural acclimatization, the effects of training, water intake and increasing salt intake, and climatic chamber and vapour-barrier suit acclimatization. The possibility of the development of a safe drug to accelerate acclimatization is considered remote. The effects of age and acclimatization in the healthy and unhealthy elderly and the very young are reviewed briefly as is also the possibility that air conditioning may have an adverse effect on acclimatization.

Acclimatization↗
PubMed2005

Development of an autotrophic culture system for the in vitro mycorrhization of potato plantlets.

An autotrophic culture system was developed for the in vitro mycorrhization of potato plantlets. Roots of micropropagated plantlets were associated to an arbuscular mycorrhizal fungus under in vitro conditions, while shoots developed under open air conditions. Several thousand spores, an extensive extraradical mycelium and an abundant root colonization were obtained. Spores were able to colonize new plantlets under the same conditions. These results support the capacity of the autotrophic culture system to continuously culture arbuscular mycorrhizal fungi and may serve as a powerful tool to investigate various aspects of the symbiosis for which a source-sink relationship and photosynthetic active tissues are necessary.

Acclimatization↗
PubMed2003

Carbonyl levels in indoor and outdoor air in Mexico City and Xalapa, Mexico.

Carbonyl compounds in air were measured at two houses, three museums, and two offices. All sites lacked air-conditioning systems. Although indoor and outdoor air was measured simultaneously at each site, the sites themselves were sampled in different dates. Mean concentrations were higher in indoor air. Outdoor means concentrations of acetone were the highest in all sites, ranging from 12 to 60 microg m(-3). In general, formaldehyde and acetaldehyde had similar mean concentrations, ranging from 4 to 32 and 6 to 28 microg m(-3), respectively. Formaldehyde and acetone mean indoor concentrations were the highest, ranging from 11 to 97 and 17 to 89 microg m(-3), respectively, followed by acetaldehyde with 5 to 47 microg m(-3). Formaldehyde and acetaldehyde had the highest mean concentration in the offices where there were smokers. Propionaldehyde and butyraldehyde concentrations did not show definite differences between indoor and outdoor air. In general, the highest outdoor and indoor hourly concentrations were observed from 10:00 to 15:00 h. Mean indoor/outdoor ratios of carbonyls exceeded 1. Formaldehyde and acetaldehyde risks were higher in smoking environments.

Air Pollutants↗
PubMed2006

Indicators of moisture and ventilation system contamination in U.S. office buildings as risk factors for respiratory and mucous membrane symptoms: analyses of the EPA BASE data.

We assessed associations between indicators for moisture in office buildings and weekly, building-related lower respiratory and mucous membrane symptoms in office workers, using the U.S. EPA BASE data, collected in a representative sample of 100 U.S. office buildings. We estimated the strength of associations between the symptom outcomes and moisture indicators in multivariate logistic regression models as odds ratios (ORs) and 95% confidence intervals (CI), controlling for potential confounding factors and adjusting for correlation among workers in buildings. This analysis identified associations between building-related symptoms and several indicators of moisture or contamination in office buildings. One set of models showed almost a tripling of weekly building-related lower respiratory symptoms in association with lack of cleaning of the drip pans under air-conditioning cooling coils (OR [CI] = 2.8 (1.2-6.5)). Other models found that lack of cleaning of either drip pans or cooling coils was associated with increased mucous membrane symptoms (OR [CI] = 1.4 (1.1-1.9)). Slightly increased symptoms were also associated with other moisture indicators, especially mucous membrane symptoms and past water damage to building mechanical rooms (OR [CI] = 1.3 (1.0-1.7)). Overall, these findings suggest that the presence of moisture or contamination in ventilation systems or occupied spaces in office buildings may have adverse respiratory or irritant effects on workers. The analysis, however, failed to confirm several risks identified in a previous study, such as condition of drain pans or outdoor air intakes, and other hypothesized moisture risks. Studies with more rigorous measurement of environmental risks and health outcomes will be necessary to define moisture-related risks in buildings.

Air Pollution, Indoor↗
PubMed1997

Occupational exposure to sevoflurane, halothane and nitrous oxide during paediatric anaesthesia. Waste gas exposure during paediatric anaesthesia.

We report the findings of a study on exposure of operating room staff to sevoflurane, halothane and nitrous oxide during induction and maintenance of anaesthesia in children. Concentrations of anaesthetic agents in the operating theatre were measured directly by highly sensitive, photoacoustic infrared spectrometer during 20 anaesthetics. Samples were taken from the breathing zones of the anaesthetist and the circulating nurse. The operating theatre was of modern design with an air conditioning system providing 20 changes of air each hour. The threshold values of 100 ppm N2O, 50 ppm isoflurane and 10 ppm halothane recommended by the United Kingdom Committee for Occupational Safety and Health (COSH) were exceeded in several cases for a short time during mask induction. After tracheal intubation, trace concentrations of sevoflurane, halothane and N2O were mostly under the recommended levels and comparable to levels measured during adult anaesthesia.

Adult↗
PubMed2003

Changing heat-related mortality in the United States.

Heat is the primary weather-related cause of death in the United States. Increasing heat and humidity, at least partially related to anthropogenic climate change, suggest that a long-term increase in heat-related mortality could occur. We calculated the annual excess mortality on days when apparent temperatures--an index that combines air temperature and humidity--exceeded a threshold value for 28 major metropolitan areas in the United States from 1964 through 1998. Heat-related mortality rates declined significantly over time in 19 of the 28 cities. For the 28-city average, there were 41.0 +/- 4.8 (mean +/- SE) excess heat-related deaths per year (per standard million) in the 1960s and 1970s, 17.3 +/- 2.7 in the 1980s, and 10.5 +/- 2.0 in the 1990s. In the 1960s and 1970s, almost all study cities exhibited mortality significantly above normal on days with high apparent temperatures. During the 1980s, many cities, particularly those in the typically hot and humid southern United States, experienced no excess mortality. In the 1990s, this effect spread northward across interior cities. This systematic desensitization of the metropolitan populace to high heat and humidity over time can be attributed to a suite of technologic, infrastructural, and biophysical adaptations, including increased availability of air conditioning.

Adolescent↗
PubMed1984

[A transportation vehicle for laparoscopically obtained follicular specimens].

Structure, function and first results with a vehicle for transportation were described. This apparatus allows to store laparoscopic harvested follicular fluids for a while in constant temperature and in air condition with 5% CO2 in compressed air. Simultaneously the follicular fluids were transported in this vehicle from operating theatre to the laboratory.

Female↗
PubMed1995

Thermal study of anti-G ensembles aboard F-16 aircraft in hot weather.

Continuing advances in the performance of new fighter aircraft have engendered requirements for more sophisticated protective clothing and life support systems. A major goal is prevention of acceleration-induced loss of consciousness. The USAF's Advanced Technology Enhanced Design G-Ensemble (COMBAT EDGE) increases acceleration tolerance by providing positive pressure to the oxygen mask; the work of pressure breathing is reduced by adding a counter-pressure bladder over the chest. However, the addition of impermeable layers over the chest reduces the area available for evaporation of sweat. This study was designed to determine whether COMBAT EDGE (CE) was demonstrably hotter than standard summer flight clothing (ST) during F-16 sorties in hot weather. Eight male pilots served as volunteer subjects, each flying missions at 1430 and 1745 h on two consecutive days, one day with CE and the other with ST. Data were logged at 1-min intervals for rectal temperature (Tre), skin temperatures at the chest and thigh (Tch and Tth) and air temperatures outside the clothing at the same two sites (Tach and Tath). The weather was stable over the 4 d of data collection with highs of 34-36 degrees C and simultaneous dewpoints of 19-23 degrees C (relative humidity 35-45%). The mean Tach was stable at 28 degrees C in flight, while individual means for Tath ranged from 22 to 25 degrees C. The lower value and greater variability at the thigh reflect its proximity to the air conditioning vent. Despite the differences in air temperature, Tch and Tth remained in the range 34-36 degrees C throughout the flights.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed2004

Comparison of environment and mice in static and mechanically ventilated isolator cages with different air velocities and ventilation designs.

The purpose of this study was to compare environmental conditions and mice in cages with four different mechanical ventilation designs and a static isolator cage. Environmental conditions (air velocity, temperature, relative humidity, bedding weight change, airborne dust, NH3, and CO2) were compared for each cage type (n = 5 per cage). Bedding type was chipped hardwood. Mouse response in each cage type was evaluated by body weight, feed consumption, water intake, location of specific behaviors, and building of bedding mounds. Commercial polycarbonate mouse caging units (29.2 x 19.1 x 12.7 cm shoebox style, stainless-steel round wire bar lids, and 7-cm-deep isolator cage filter tops) were modified to fit the mechanical ventilation cage types and were used for the static isolator cages. Mechanically ventilated cages were fitted with forced air inlets centered 5 cm above the cage floor on the 19.1 cm-side of the cage. Inlet air velocity was either 40 or 200 feet/min (n = 10 cages each), and the air volume exchange rate was 9.3 L/min. In half of the mechanically ventilated cages, the exhaust air was forced through a filter in the isolator cage top, whereas in the remaining mechanically ventilated cages, the air was forced through a single exhaust port fixed in the narrow side of the cage top directly above the air inlet. Inlet air velocity but not exhaust design affected intracage air velocity distribution. Other environmental conditions were similar between the four mechanical ventilation designs. Relative to the mechanically ventilated cages, the static isolator cages had lower air velocities, higher relative humidities, higher NH3 levels, higher CO2 levels, lower body weight gain, and lower water consumption; temperatures, particulate levels, and feed consumption rates did not differ significantly between cage types. Locations of bedding mounds and behaviors were similar in all cage treatments.

Air↗