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PubMed1985

An open circuit respiration unit for calorimetric studies with small animals.

Two open-circuit respiration chambers for small animals (rats, poultry and rabbits) have been built at the Estación Experimental del Zaidín. The respiration facility is air-conditioned, the temperature and the relative humidity in the chambers can be regulated from about +15 to +30 degrees C and from 60 to 90%, respectively. The air flow is determined by the differential pressure principle, CO2 measurement is by the infra-red technique and O2 analyser is of the paramagnetic type. The present work describes the technical details of the respiration plant and the calibration procedures of the whole system.

Air Conditioning↗
PubMed2003

Positive effects of a fresh air filtration system on hay fever symptoms.

BACKGROUND: Avoidance of allergen exposure is the basic preventive measure in reducing symptoms of immediate-type allergies. As room air cleaners were found to have no benefic effect on general health, their use has not been recommended. The purpose of this study was to evaluate the effect of a fresh air filtration system installed in the bedrooms of non-air-conditioned homes on hay fever symptoms. METHODS: In a placebo-controlled, double-blind, two-period, crossover study, we investigated the effectiveness of a fresh air filtration system installed in the bedrooms of volunteers suffering from hay fever. RESULTS: Volunteers only suffering from pollinosis reported an improvement of their allergy symptoms. We observed a significant decrease in nighttime hay fever symptoms and an increase in morning peak expiratory flow rates (PEFR). No effects were recognized in volunteers who additionally had perennial allergy. CONCLUSION: Based upon these results, the installation of fresh air filtration systems in bedrooms should be recommended for patients suffering from hay fever.

Adult↗
PubMedDate not supplied

Pulmonary functions in air conditioner users.

Air conditioning may affect human health since it has profound effect on our environment, than just lowering temperature. The present study was planned to assess the effect of air conditioners (AC) on pulmonary functions in young healthy non-smoker males. The study group comprised of ten subjects who were using AC's in their cars for at least 1 hr daily since last 6 months. While ten subjects who did not use AC at all served as controls. The pulmonary functions were assessed using PK Morgan 232 spirometer in a closed room. The peak expiratory flow rate (PEFR) and Forced expiratory flow between 25-75% of vital capacity (FEF25-75) were significantly reduced in subjects using car AC's. Inspiratory flow rates also showed a trend towards decline in AC users but could not reach the level of significance. The lung volumes and capacities were not significantly different in the two groups except for forced expiratory volume in 0.5 sec (FEV 0.5 sec), which also decreased in AC users. The airway resistance and lung compliance did not show significant change. In the presence of normal FEV1, reduced FEF25-75% which is the flow rate over the middle half of vital capacity, is an evidence of mild airflow limitation. The result is suggestive of predisposition of AC users towards respiratory disorders in form of mild airflow restriction.

Adolescent↗
PubMed1994

Shiftwork and heat stress in an intensive care unit.

This paper reported the results of investigation on shiftwork and heat stress in an intensive care unit. The aim of this study was to analyse the physiological strain of nurses during the three shifts (Morning, Afternoon, Night) in relation to the specific microclimatic conditions and job activities. 8 professional nurses (6 female and 2 male), aged between 21 and 38 years (mean 29.8 +/- 5.6 years), having from 3 to 18 years service, were monitored throughout a complete working cycle of 4 days. They worked on a three shift system at fast rotation. Their working environment was an independent unit for intensive care and expert surgical treatment which was entirely air conditioned. The observation indexes included: twenty-five blood parameters, ten urine parameters, net cardiac cost and relation cardiac cost, etc. The results of the investigation have not evidenced serious alterations of the psycho-physical conditions of the nurses, but do pointed out some problems pertaining both to the environmental and physiological conditions.

Adult↗
PubMedDate not supplied

Effects of hyperoxia and beta-adrenergic stimulation on pulmonary surfactant in neonatal rabbits.

To study the effects of hyperoxia and beta-adrenergic stimulation on pulmonary surfactant in the neonatal lung, we measured disaturated phosphatidylcholine (DSPC) and [14C]choline incorporation into DSPC, obtained from alveolar lavage and lung tissue. We used an isolated salt-perfused rabbit lung preparation from neonatal rabbits exposed to room air or greater than 95% oxygen for 3 days. There were four experimental groups: room air, basal condition; room air, beta-adrenergic stimulation; hyperoxia, basal conditions; and hyperoxia, beta-adrenergic stimulation. Hyperoxia caused a significant decrease in lavage and intracellular [14C]DSPC specific activity, and a decrease in intracellular DSPC suggesting depressed surfactant synthesis. Beta-stimulation in room air caused a decrease in lavage DSPC, an increase in DSPC, and [14C]DSPC fraction released, consistent with increased uptake for reutilization. With hyperoxia and beta-stimulation, there is an increase in total DSPC in the lavage; lavage [14C]DSPC specific activity is similar to that of the basal hyperoxia group (i.e., depressed compared with the room air state); intracellular [14C]DSPC specific activity does not differ from basal, hyperoxia, or beta-stimulated, room air groups, all being depressed compared with basal, room air conditions. Intracellular DSPC in the beta-stimulated group is less affected by hyperoxia than the basal groups. It appears that prolonged exposure to hyperoxia is manifested primarily by a decrease in [14C]DSPC specific activity suggesting alterations in surfactant synthesis, though DSPC in the lavage is not altered. Beta-adrenergic stimulation may enhance release of newly synthesized surfactant into the alveoli, and possibly enhances uptake for reutilization. The enhancement of surfactant release seems to be preserved after prolonged hyperoxia.

Adrenergic beta-Agonists↗
PubMed1979

[Effect of proximate environment on drug susceptibility of mice (author's transl)].

The present study was performed in order to elucidate the effect of proximate environment on drug susceptibility of mice. Three experiments were carried out independently. In the first experiment, mongrel and ddS mice produced under an unsatisfactory control of proximate environment were purchased, and acute toxicity tests of thiamine hydrochloride (B1HCl) and isonicotinic acid hydrazide (INAH) were practiced at two different conditioned rooms. In the second experiment, ddY mice produced under the conventional environment controlled to a certain extent were purchased, and the toxic effect of B1HCl was examined under the similar environment. In the third experiment, the sensitivity to B1HCl of RFVL mice produced under the strict barrier system was tested at the severe air-conditioned room. LD50 and their fLD50 values were calculated by Litchfield-Wilcoxon's method, and the variance analyses were carried out. The severer the environmental control after the purchase of mice turned to the higher the drug sensitivity. This respect was more remarkable in INAH of which the toxic response is appeared slowly compared with B1HCl. Furthermore, seasonal variation was found in LD50 values. However, seasonal effect differed from rearing and experimental conditions. In the third experiment which these proximate environments were controlled severely, seasonal variation was very small. From the results of these experiments, it was defined that the use of animals produced under the satisfactory rearing condition and severe environmental control are necessary for animal experiments.

Air Conditioning↗
PubMed1989

A microcomputer-based respiratory heat exchange facility for use in the diagnosis of thermally induced asthma.

Exercise-induced asthma is prevalent in many asthmatics and during the winter months can be exacerbated by cold air inhalation. A laboratory facility was required to permit early diagnosis of cold air sensitivity in these patients. This paper describes the development of a modular air conditioning system to produce a range of inhalative thermal burdens and the microcomputer interfacing to measure the rate of airway heat loss imposed. A single-stage refrigerator was built capable of cooling 150 l/min air to -25 degrees C. This was also used to generate dry ambient temperature air by rewarming the chilled air supply. An air humidifier was developed based upon natural convection and evaporation. It was capable of raising 150 l/min ambient air to 37 degrees C, 100 per cent relative humidity. In two pilot studies of 18 asthmatics it was found that the rate of respiratory heat exchange could be correlated with the magnitude of post exertional bronchoconstriction (lung dysfunction) and that exercise-induced asthma could be minimized by attenuating the rate of airway heat loss.

Adult↗
PubMed2003

Effective protection of allogeneic stem cell recipients against Aspergillosis by HEPA air filtration during a period of construction--a prospective survey.

High incidence of aspergillosis on transplant units or hematological wards without HEPA air conditioning during periods of demolishing or construction has been reported by several investigators. Here we report monitoring of fungal air contamination during a period of construction on a stem cell transplantation ward using the gravity air-setting plate (GASP) method. Fungal air contamination in HEPA-conditioned patient rooms was constantly low, independent from construction activity. Outside of the patient rooms at the ward's corridor, the fungal load was significantly higher with some peak values. Outside the transplant unit measures of construction led to a significant increase of fungal spore concentration in air. Transplant activity was not reduced during construction and patients were nursed strictly under HEPA conditions. Patients were monitored prospectively for incidence of infections since 1990 and data of patients grafted during construction (n = 28) were compared to those grafted outside building activity (n = 652). An increase of aspergillosis during construction could be clearly excluded. It can be concluded: Nursing of patients undergoing stem cell transplantation in HEPA-conditioned rooms is an effective protection against acquisition of aspergillus-infection, even under environmental conditions with increased air contamination by conidia. The gravity air-setting plate (GASP) method is not expensive and easy to use and allows reliable and quantitative aerobiological spore monitoring.

Air↗
PubMed2003

Air flow and particle control with different ventilation systems in a classroom.

Most ventilation and air conditioning systems are designed without much concern about how settling particles behave in ventilation air flows. For displacement ventilation systems, designers normally assume that all pollutants follow the buoyant air flow into an upper zone, where they are evacuated. This is, however, not always true. Previous studies show that high concentrations of settling respirable particles can be found in the breathing zone, and that the exposure rates can be a health hazard to occupants. The emphasis here is on how ventilation systems should be designed to minimize respirable airborne particles in the breathing zone. The supply and exhaust conditions of the ventilation air flow are shown to play an important role in the control of air quality. Computer simulation programs of computational fluid dynamics (CFD) type are used. Particle concentrations, thermal conditions and modified ventilation system solutions are reported.

Air Movements↗
PubMed1989

[A case of mass legionellosis infection in an enterprise of the rubber technology industry].

On the basis of the analysis of the sanitary and hygienic conditions, epidemiology of a mass disease, clinical picture of the disease during a 6-month trial period the problems of differentiated diagnosis of infectious and toxic processes, examination of capacity for work, the course of diseases were studied in 219 workers who had had legionellosis. The participation of various specialists in the analysis of analogous cases at the enterprises with chemical environmental contamination and developed systems of air conditioning was considered necessary.

Air Conditioning↗
PubMed2001

A heart rate evaluation approach to determine cost-effectiveness an ergonomics intervention.

This paper describes a hear-rate methodology to determine the cost-effectiveness of an ergonomics intervention to reduce workload and improve working conditions. This is a practical approach as opposed to the energy expenditure technique that is difficult to implement in natural settings. This was a laboratory study using a large excavator cabin with devices to simulate excavation operations. Mean heart rate was used to calculate the required rest time during a shift with or without air-conditioning. The criterion for evaluation was differences in required rest time during a shift under these 2 conditions. The simplicity and objectivity of this approach invites use to solve the problem of the economic evaluation of ergonomics interventions.

Air Conditioning↗
PubMed1996

Risk factors for hypothermia in psychiatric patients.

Hypothermia occurs when the core body temperature falls below 95 degrees F (35 degrees C). Several conditions which can occur in the psychiatric population increase the risk of hypothermia: nocturnal enuresis, seizure disorder, debilitating physical illness, and mental retardation. The risk of hypothermia is further increased by the use of several classes of medications used to treat psychiatric disorders: antipsychotics, beta-adrenergic antagonists, benzodiazepines, and other sedatives. Air-conditioning is also identified as a risk factor for hypothermia. Hypothermia is posited as a possible link between antipsychotic medication and sudden unexplained death. Suggestions for further investigation are made, and clinical recommendations are offered to reduce the risk of hypothermia in the psychiatric patient population.

Air Conditioning↗
PubMed2005

Symptomatic effects of exposure to diluted air sampled from a swine confinement atmosphere on healthy human subjects.

Aerial emissions from a swine house at North Carolina State University's field laboratory were diluted to a level that could occur at varying distances downwind from a confined animal feeding operation (CAFO) both within and beyond the property line, and these emissions were delivered to an environmental exposure chamber. The study design consisted of two 1-hr sessions, one in which 48 healthy human adult volunteers were exposed to diluted swine air and another in which they were exposed to clean air (control). Objective measures of blood pressure, temperature, heart rate, respiratory rate, lung function, nasal inflammation, secretory immunity, mood, attention, and memory were correlated with objective measures of air quality. Ratings of perceived (self-reported) health symptoms were also obtained. The mean levels of airborne constituents in the swine air condition were hydrogen sulfide (24 ppb), ammonia (817 ppb), total suspended particulates (0.0241 mg/m3), endotoxin (7.40 endotoxin units/m3), and odor (57 times above odor threshold). No statistical differences on objective measures of physical symptoms, mood, or attention resulted from the 1-hr exposure to swine emissions in the environmental chamber when compared with clean air for healthy human volunteers. However, subjects were 4.1 (p = 0.001) times more likely to report headaches, 6.1 (p = 0.004) times more likely to report eye irritation, and 7.8 (p = 0.014) times more likely to report nausea in the swine air (experimental) condition than in the control condition. These results indicate that short-term exposure in an environmental chamber to malodorous emissions from a swine house at levels expected downwind can induce clinically important symptoms in healthy human volunteers.

Adult↗
PubMed2001

The adaptive model of thermal comfort and energy conservation in the built environment.

Current thermal comfort standards and the models underpinning them purport to be equally applicable across all types of building, ventilation, occupancy pattern and climate zone. A recent research project sponsored by the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE, RP-884) critically evaluated these assumptions by statistically analysing a large database of research results in building comfort studies from all over the world (n=22,346). The results reported in this paper indicated a clear dependence of indoor comfort temperatures on outdoor air temperatures (instead of outdoor effective temperature ET* used in RP-884), especially in buildings that were free-running or naturally ventilated. These findings encourage significant revisions of ASHRAE's comfort standard in terms of climatically relevant prescriptions. The paper highlights the potential for reduced cooling energy requirements by designing for natural or hybrid ventilation in many moderate climate zones of the world.

Acclimatization↗
PubMed1985

Occurrence of moulds in modern living and working environments.

The occurrence of saprophytic moulds in indoor environments and their potential hazards to human health are discussed. In addition to mesophilic species, xerophilic moulds appear to be common, often developing together with mites. Allergic and non-allergic symptoms are reported when patients are exposed to moulds in homes, schools and working places. Air-conditioning systems are consistently involved with mould development. Complaints of eye-, nose- and throat-irritation as well as fatigue seem to be correlated with unpleasant odours produced by abundant mould growth, but the relationship between the symptoms and the odours is not understood. The role of air-borne mycotoxins is discussed. Methods to detect moulds in indoor environments are described. Because no single method or cultivation medium is sufficient to detect all the various indoor moulds, a combination of air sampling, direct microscopic examination and cultivation on both standard and low water activity media is recommended.

Air Conditioning↗
PubMed2004

Frequency of open windows in motor vehicles under varying temperature conditions: a videotape survey in Central North Carolina during 2001.

Air pollution exposures in the motor vehicle cabin are significantly affected by air exchange rate, a function of vehicle speed, window position, vent status, fan speed, and air conditioning use. A pilot study conducted in Houston, Texas, during September 2000 demonstrated that useful information concerning the position of windows, sunroofs, and convertible tops as a function of temperature and vehicle speed could be obtained through the use of video recorders. To obtain similar data representing a wide range of temperature and traffic conditions, a follow-up study was conducted in and around Chapel Hill, North Carolina at five sites representing a central business district, an arterial road, a low-income commercial district, an interstate highway, and a rural road. Each site permitted an elevated view of vehicles as they proceeded through a turn, thereby exposing all windows to the stationary camcorder. A total of 32 videotaping sessions were conducted between February and October 2001, in which temperature varied from 41 degrees F to 93 degrees F and average vehicle speed varied from 21 to 77 mph. The resulting video tapes were processed to create a vehicle-specific database that included site location, date, time, vehicle type, vehicle color, vehicle age, window configuration, number of windows in each of three position categories (fully open, partially open, and closed), meteorological factors, and vehicle speed. Of the 4715 vehicles included in the database, 1905 (40.4%) were labeled as "open," indicating a window, sunroof, or convertible top was fully or partially open. Stepwise linear regression analyses indicated that "open" window status was affected by wind speed, relative humidity, vehicle speed, cloud cover, apparent temperature, day of week, time of day, vehicle type, vehicle age, vehicle color, number of windows, sunroofs, location, and air quality season. Open windows tended to occur less frequently when relative humidity was high, apparent temperature (a parameter incorporating wind chill and heat index) was below 50 degrees F, or the vehicle was relatively new. Although the effects of the identified parameters were relatively weak, they are statistically significant and should be considered by researchers attempting to model vehicle air exchange rates.

Air Movements↗
PubMed1998

Hydrophilic membrane-based humidity control.

A dehumidification system for low gravity plant growth experiments requires the generation of no free-liquid condensate and the recovery of water for reuse. In the systems discussed in this paper, the membrane is a barrier between the humid air phase and a liquid-coolant water phase. The coolant water temperature combined with a transmembrane pressure differential establishes a water flux from the humid air into the coolant water. Building on the work of others, we directly compared different hydrophilic membranes for humidity control. In a direct comparison of the hydrophilic membranes, hollow fiber cellulose ester membranes were superior to metal and ceramic membranes in the categories of condensation flux per surface area, ease of start-up, and stability. However, cellulose ester membranes were inferior to metal membranes in one significant category, durability. Dehumidification systems using mixed cellulose ester membranes failed after operational times of only hours to days. We propose that the ratio of fluid surface area to membrane material area (approximately = membrane porosity) controls the relative performances among membranes. In addition, we clarified design equations for operational parameters such as the transmembrane pressure differential. This technology has several potential benefits related to earth environmental issues including the minimization of airborne pathogen release and higher energy efficiency in air conditioning equipment. Utilizing these study results, we designed, constructed, and flew on the space shuttle missions a membrane-based dehumidification system for a plant growth chamber.

Air Conditioning↗