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The thermal exchanges between lung and working or living environment constitute a very small amount of the total thermal exchange of the human body. They mainly depend on temperature and humidity gradients between inspired and expired air and on ventilatory levels as well. In spite of the smallness of such exchanges regarding the thermal steady state of the body, the variations of the climate physical parameters can greatly affect the lung either from the subjective or the objective point of view. Air humidity, temperature and ventilation are here considered as causes of respiratory discomfort and as risk factors of respiratory disease. It has been pointed out that the same parameter levels can exert a favourable or unfavourable influence on respiratory tract. For instance low humidity values can support the respiratory infections but usually prevent asthma crisis caused by indoor mite sensitization. Sometimes among the causes of respiratory risk can be involved the artificial systems of ventilation and humidification (air conditioning, humidifiers). It is not possible to set proper limit values for the physical parameters but only ranges where to determine the best combination for each single situation. The width of such ranges as well as the dysfunctioning of the artificial conditioning systems can in particular cases support some conditions of respiratory risk.
A critical assessment of available waste anaesthetic gas scavenging devices was made by simulating the worst theatre conditions as well as ideal conditions. Only one of the scavenging devices tested proved to be unacceptable. However, the critical nature of suction flow rates was revealed and the ineffectiveness of air conditioning in the absence of adequate scavenging was highlighted.
Both for the nose and the lower airways there is an extensive subepithelial capillary network. That for the nose is fenestrated, and this is true for the tracheobronchial tree of rats, guinea pigs, and hamsters, and for that of human asthmatics. However, healthy humans, dogs, and sheep have capillaries without fenestrations except for those close to neuroepithelial bodies and submucosal glands. Deeper in the mucosa there is a capacitance system of vessels, conspicuous in the nose but present also in the lower airways of rabbits and sheep and, to a lesser extent, in those of dogs and humans. Both for the nose and the lower airways, parasympathetic nerves are vasodilator, sympathetic nerves are vasoconstrictor, and sensory nerves are able to release dilator neuropeptides. Most inflammatory and immunologic mediators are vasodilator. A conspicuous difference between the nasal and lower airway vasculatures is the presence of arteriovenous anastomoses only in the former. Countercurrent mechanisms also exist in the nose to increase its efficiency in air conditioning, but they have not been established for the trachea. The pulmonary vasculature could be part of such a system for the bronchi. Distension of the airway vasculature thickens the mucosa, probably both by vascular distension and by edema formation. The latter can lead to exudation into the airway lumen. These processes have not been well quantitated, and the balance sheet of capillary and capacitance vessel volumes, interstitial liquid volume, and exudate volume needs to be worked out in physiologic and pathologic conditions.
The Authors have taken under study 6 office buildings and a total of 165 work stations with VDTs. Lighting conditions, postures, indoor climate and air-quality have been evaluated, besides worker's subjective approach sounded by individual questionnaire. Concerning visual comfort, it has been noticed that the most simple and well-known rules are often disregarded, such as avoiding to place a screen in front of a light source because of its glare. Also, operators postures are often incorrect, making problems related to their own fixity worse. Air conditioning systems assure almost excellent conditions for thermal comfort, but air changes are often poor and microbiologic quality suffers from plant's inadequate servicing. Finally, the survey of questionnaires shows a complaint percentage which only partly corresponds with the objective data collected, reflecting instead an uneasiness to the kind of work and its organisation.
The risk of transmission of nosocomial infections associated with technical installations in hospitals probably is not very important. The way of infection (e.g. airborne particles, droplets, fluids, fomites, contact with persons) must be considered and an estimation as to their importance should be tried. Transport systems and air-conditioning plants are discussed as possible transmitters of infectious particles by air and UV-radiation and air-locks in their role as preventive measures. Fluides which can allow a microbial growth are part of many sanitary installations and medical equipment. They may cause transmissions of great numbers of pathogenes to susceptible patients. In this context, ultrasonic inhalators, irrigators, dialysis equipment and faucet aerators are discussed. Concerning transmission by contact, bed-pan washers, endoscopes and anaesthetic tools are mentioned and finally the role of industrial procedures, the extent and function of which can't be supervised by the medical personn,el, must be submitted to adequate microbiological controls. Physicians should pronounce more clearly then before their interest in equipment which can easily be sterilized.
Clavicular air sac pressure, arterial blood gases and pH, and rectal temperature were measured in treadmill-exercised cockerels breathing air, 10% O2 in N2 or a mixture of 10% O2/3% CO2 in N2. Air sac pressures were used to estimate changes in the rate and the relative depth of breathing. In air-breathing conditions exercise took place at two intensities corresponding to treadmill speeds of 3.2 and 5.0 km h-1, respectively. Rectal temperature increased by 0.5 degrees C but there was no sign of thermal hyperventilation and arterial PCO2 remained constant. Increased ventilation was mainly brought about by changes in respiratory rate, with relatively small increases in depth. During exercise at 3.2 km h-1 inhalation of 10% O2 in N2 produced a 35% increase in ventilation and breathing became faster and shallower. Arterial PCO2 fell by 3-4 Torr, apparently as a result of lung hyperventilation. Addition of 3% CO2 to the hypoxic gas restored normal arterial PCO2 and reversed the trend to polypneic breathing. However, it failed to produce an exact matching of respiratory characteristics with those observed during isocapnic exercise hyperpnea. It is concluded that rapid, shallow breathing during hypocapnic hypoxia in running birds serves as a mechanism to minimize lung hyperventilation and CO2 washout. This reflex, which may stem from the intrapulmonary CO2 receptors, occurs in the face of a severe hypoxic challenge. Failure to match respiratory characteristics during isocapnic hypoxia and isocapnic exercise may be due to an inhibitory effect of the inhaled CO2 on these receptors.
The physiological and subjective responses of six sedentary subjects wearing half-facepiece respirators were observed over a wide range of room and respirator air conditions. Room air and dew-point (Ta:Tdp) temperatures were 25:11 degrees, 30:13 degrees, and 35:16 degrees C in still air. Respirator air temperatures were maintained independently of room conditions at 27 degrees, 30 degrees, 33 degrees, and 36 degrees C with relative humidity levels of 47% and 73%. Physiological measurements included local skin and dew-point temperatures. Subjective judgments of acceptability, thermal sensation, degree of discomfort, sense of skin moisture, and difficulty of breathing were recorded separately for the thermal environment in the room and inside the respirator. Respirator temperatures cooler than 33 degrees C were always comfortable and 100% acceptable; respirator air temperatures above 33 degrees C or higher humidity levels decreased respirator acceptability. Acceptability of the respirator environment decreased as lip temperature increased above 34.5 degrees C or when respirator dew-point temperature increased above 20 degrees C. Increased respirator air temperature and humidity often made breathing seem "slightly hard." The respirator conditions influenced the subjects' judgment of the acceptability of the surrounding thermal environment.
Authors analysed 96 workers exposed to air conditioning system (Group A), and 71 workers (Group B) breathing normal ambient air. 38 workers in group A had a positive clinical history of "Monday morning miseries". Eight cases with the diagnosis hypersensitivity pneumonitis, acute and chronic form was based on environmental history, clinical investigations, physical examination, Chest-X-ray examination, immunological test "in vivo" and "in vitro" with common allergens and antigen "Monday morning miseries", ELISA, spirometry and PEFR (Peak Expiratory Flow-Rate) measurements. Exposure to contaminated air may be responsible for morbidity and reduced performance of workers.
The changes in respiratory water loss with time, expressed as the mass of water vapour lost per liter BTPS of ventilation (MH2O), and expired temperature (TE), used to calculate the relative humidity (ERH), were investigated in ten normal subjects while breathing warm dry air by mouth (PIH2O = 0 kPa; TI = 30 degrees C): at rest for a period of 35 min; during 15 min light muscular exercise (50 W); at increasing work load from 50 to 100 W between the 5th and 10th min of the exercise. The data collected were compared to those obtained in room air conditions (PIH2O = 0.68-1.3 kPa) and under conditions with slightly heated inspired air (TI = 28-30 degrees C). At rest, when breathing dry warm air MH2O and ERH fell during the first 15 min, while they recovered their initial values during the last 20 min. In contrast no differences in MH2O or ERH were observed when breathing ambient warm air. At constant and moderate work load for 15 min, the respiratory water loss fell significantly (compared to the 5th min) at the 10th and the 15th min when breathing warm dry air. The added hyperpnea which was obtained by increasing work load from 50 to 100 W between the 5th and 10th min of exercise did not further reduce MH2O and ERH. The transient fall in MH2O and ERH, which lasted at least 15 min either at rest or during muscular exercise, suggested that the mechanism underlying humidification of expired gas is overwhelmed by thermal stress. Since the upper airways mucosa is unable to saturate expired gas, this also suggested that the mucosa is dehydrated and probably hyperosmotic. The progressive recovery in MH2O and ERH after 15 min of warm dry air breathing at rest, suggest operation of a slow adaptive mechanism.
Improvements in carbon assimilation and water-use efficiency lead to increases in maximum leaf area index at elevated carbon dioxide concentration ([CO(2)]); however, the molecular drivers for this increase are unknown. We investigated the molecular basis for changes in leaf development at elevated [CO(2)] using soybeans (Glycine max) grown under fully open air conditions at the Soybean Free Air CO(2) Enrichment (SoyFACE) facility. The transcriptome responses of rapidly growing and fully expanded leaves to elevated [CO(2)] were investigated using cDNA microarrays. We identified 1,146 transcripts that showed a significant change in expression in growing versus fully expanded leaves. Transcripts for ribosomal proteins, cell cycle, and cell wall loosening, necessary for cytoplasmic growth and cell proliferation, were highly expressed in growing leaves. We further identified 139 transcripts with a significant [CO(2)] by development interaction. Clustering of these transcripts showed that transcripts involved in cell growth and cell proliferation were more highly expressed in growing leaves that developed at elevated [CO(2)] compared to growing leaves that developed at ambient [CO(2)]. The 327 [CO(2)]-responsive genes largely suggest that elevated [CO(2)] stimulates the respiratory breakdown of carbohydrates, which provides increased energy and biochemical precursors for leaf expansion and growth at elevated [CO(2)]. While increased photosynthesis and carbohydrate production at elevated [CO(2)] are well documented, this research demonstrates that at the transcript and metabolite level, respiratory breakdown of starch is also increased at elevated [CO(2)].
The effects of soil temperature on the shoot phenology, carbohydrate dynamics, chlorophyll fluorescence and cold hardiness of 4-year-old Norway spruce seedlings (Picea abies L. Karst.) were studied. The experiment was carried out under controlled conditions in the Joensuu dasotrons. Air conditions were similar but soil temperatures differed by treatments (9, 13, 18 and 21 degrees C) during the second growing period in the dasotrons. The after-effects of the treatments were investigated during the third growing period following the treatments. Low soil temperature increased the starch content of needles and delayed the loss of starch at the end of the growing season. The photochemical efficiency (F(v)/F(m)) of the PSII of the current-year needles was reduced at the lowest soil temperature. The cold hardiness of needles correlated with the soluble sugar content. The differences in soil temperature had no effect on the timing of bud burst. No after-effects from the treatments were observed during the third growing period in the dasotrons.
Sixteen healthy women users and nonusers of oral contraceptives (OC) volunteered to document a set of circadian rhythms. Nine were taking OC providing ethynyl estradiol (0.03-0.05 mg/24h, 21 days/month) combined with DL- or L-norgestrel or norethisterone. There was no group difference (p > 0.05) in median age (22 years), weight (57 kg), and height (162) cm). Data were obtained at fixed hours, 5 times/24h, during a 48-h span, in November. (Day activity from approximately 08:00 to approximately 23:00 h and night rest). Environmental conditions were controlled, using air-conditioned rooms of constant temperature (26 degrees +/- 0.5) and relative humidity 45% +/- 1. Both cosinor and ANOVA were used for statistical analyses. All circadian rhythms were validated with one exception: that of salivary melatonin was not detected in OC users. The 24h mean (M) exhibited group differences for certain variables: M was greater in OC than non-OC users for systolic blood pressure (p < 0.0001), heart rate (p < 0.01), skin blood flow (p < 0.04), and transepidermal water loss (p < 0.02). M was lower in OC than non-OC users in salivary cortisol (p < 0.04) and skin amino acids (p < 0.003). No group difference was detected in any other documented rhythms: diastolic blood pressure, grip strength of both hands, oral temperature, self-rated fatigue, and the skin variables of urea, lactate, triglycerides, and acid phosphatase activity.
PURPOSE: To assess tear function in radiologists. MATERIALS AND METHODS: The study included 71 volunteers divided into 2 groups; 36 radiologists (Group 1) and 35 non-radiologist controls (Group 2). The noted ophthalmologic symptoms in both groups were burning, stinging, redness, sensation of a foreign body, photophobia, and blurred vision. Schirmer's 1 and tear break-up time tests were used to assess tear function. RESULTS: The distribution of eye symptoms in Group 1 was as follows: 16 radiologists (44.4%) presented with burning and stinging, 17 (47.2%) with the sensation of a foreign body, 23 (63.8%) with redness, 11 (30.5%) with blurred vision, and 5 (13.8%) with photophobia. As for Group 2, the following symptoms were noted: burning and stinging in 8 (22.8%), sensation of a foreign body in 5 (14.2%), redness in 6 (17.1%), blurred vision in 3 (8.5%), and photophobia in 1 control volunteer (2.8%). Tear break-up time test scores were 8.4 for Group 1 and 15.4 for Group 2, whereas Schirmer's 1 test scores were 9.1 and 16.1 for Groups 1 and 2, respectively. CONCLUSION: As a conclusion, dry eye syndrome occurs significantly more frequently in radiologists compared to non-radiologist. The working conditions and circumstances, including air-conditioned rooms, use of negatoscopes, and exposure to diagnostic radiation may be possible causative factors of this statistical outcome.
The contamination by nitrous oxide of an operating room atmosphere was studied in a number of experiments, in the absence of personnel and using a gaschromatographic method. The evacuating device of the anesthesia machine proved to be ineffective to overcome the hazard of leaks in the breathing system, whereas the air conditioning flow rates (12 outside air changes per hour) minimized waste anesthetic gas concentrations.
UNLABELLED: The thermal environment and air quality in buildings affects occupants' health, comfort and performance. The heating, ventilating and air-conditioning (HVAC) of buildings today is designed to provide a uniform room environment. However, large individual differences exist between occupants in regard to physiological and psychological response, clothing insulation, activity, air temperature and air movement preference, etc. Environmental conditions acceptable for most occupants in rooms may be achieved by providing each occupant with the possibility to generate and control his/her own preferred microenvironment. Furthermore, HVAC systems should be designed to protect occupants from airborne transmission of infectious agents that may be present in exhaled air. Personalized ventilation is a new development in the field of HVAC and has the potential to fulfill the above requirements. This paper reviews existing knowledge on performance of personalized ventilation (PV) and on human response to it. The airflow interaction in the vicinity of the human body is analyzed and its impact on thermal comfort and inhaled air quality is discussed together with control strategies and the application of PV in practice. Performance criteria are defined. Recommendations for design of PV that would be in compliance with the criteria are given. Future research needed on the topic is outlined. PRACTICAL IMPLICATIONS: Personalized ventilation can improve occupants' comfort, decrease SBS symptoms and reduce the risk of transmission of contagion between occupants in comparison with total volume ventilation. However in order to perform efficiently in rooms in practice, the design (air distribution, control, etc.) has to be carefully considered together with type of occupant activity (occupancy rate, occupied density, etc.).
The effect of laminar air flow conditions and clean-room dress on the microbial contamination rates of intravenous admixtures was investigated. Intravenous admixtures were prepared by one investigator using aseptic technique under four environmental conditions: laminar air flow conditions with clean-room dress; laminar air flow without clean-room dress; clean table top with clean-room dress; and clean table top without clean-room dress. In each environmental condition, 350 admixtures were compounded. Negative-control samples (n = 150) were also tested, as were 10 positive-control samples. Samples were tested in each of two growth media and incubated at 35 degrees C for 14 days or until growth occurred. The incidence of contamination of admixtures compounded in laminar air flow conditions was significantly less than the contamination of those compounded on a clean table top (p less than 0.05) regardless of the operator's dress. The incidence of contamination of admixtures compounded while wearing clean-room dress was not significantly different from those prepared while not wearing clean-room dress regardless of the environment in which the admixture was prepared. The overall low level of contamination [0.79% (11/1400)] was inconclusive regarding the effect of dress on the incidence of contamination when admixtures were prepared under LAF conditions. It is concluded that, when one adheres to aseptic technique, the environment in which admixtures are compounded is the most important variable affecting the microbial contamination rate.