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At least 577 records · Page 32Linked to original sources
PubMed2006

Mortality of patients with heatstroke admitted to intensive care units during the 2003 heat wave in France: a national multiple-center risk-factor study.

OBJECTIVE: Heatstroke requires active body cooling and organ failure supportive care. Although heat waves are expected to recur over the next decades, little is known about the risk factors for mortality in heatstroke patients. We examined the prognosis and risk factors for hospital mortality in patients with heatstroke admitted to an intensive care unit (ICU) during the heat wave in France in August 2003. DESIGN: A questionnaire was sent to the physicians leading an ICU in France to identify the patients admitted with heatstroke during August 2003. Data included demographics, factors predisposing to heatstroke, severity during the first day in the ICU, air conditioning in the ICU, and hospital mortality. Risk factors for mortality were determined in multivariate Cox proportional hazards analysis. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Data were obtained for 345 patients. Hospital mortality was 62.6%. Occurrence of heatstroke at home or in a healthcare facility rather than in a public location, high Simplified Acute Physiology Score II, high body temperature, prolonged prothrombin time, use of vasoactive drugs within the first day in the ICU, and patient management in an ICU without air conditioning were independently associated with an increased risk of death. CONCLUSIONS: Mortality of patients admitted to the ICU with heatstroke is high. Predictors of mortality are available within the first 24 hrs after admission. Furthermore, in this study, air conditioning in the ICU was associated with improved outcome.

Aged↗
PubMedDate not supplied

Numerical simulation of intranasal airflow after radical sinus surgery.

PURPOSE: Radical sinus surgery disturbs intranasal humidification and heating of inspired air, resulting in reduced air conditioning mainly caused by a disturbed airflow. Therefore, the aim of this study was to simulate the intranasal airflow after radical sinus surgery during inspiration by means of numerical simulation. MATERIAL AND METHODS: A bilateral model of the human nose with maxillectomy, ethmoidectomy, and resection of the lateral nasal wall and the turbinates on one side based on a multislice computed tomographic scan was reconstructed. An unsteady numerical simulation displaying the intranasal airflow patterns applying the computational fluid dynamics solver Fluent 6.1.22 was performed. RESULTS: Spacious vortices throughout the entire nasal cavity and the paranasal sinuses caused by the radical resections occurred, causing a less-intense contact between air and the surrounding nasal wall. An enlargement of the nasal cavity volume and a reduction of the nasal surface area in ratio to the nasal cavity volume could be observed. CONCLUSIONS: Aggressive sinus surgery leads to disturbed intranasal air conditioning caused by disturbed intranasal airflow patterns and a reduction of the surface area in relation to the nasal volume. The presented numerical simulation demonstrates the close relation between air conditioning and intranasal airflow. It can be helpful to understand and interpret in vivo measured data of intranasal temperature and humidity.

Biophysical Phenomena↗
PubMed2006

[Heat waves: health impacts].

During the summer of 2003, record high temperatures were reported across Europe, causing thousands of casualties. Heat waves are sporadic recurrent events, characterised by intense and prolonged heat, associated with excess mortality and morbidity. The most frequent cause of death directly attributable to heat is heat stroke but heat waves are known to cause increases in all-cause mortality, specially circulatory and respiratory mortality. Epidemiological studies demonstrate excess casualties cluster in specific risk groups. The elderly, those with chronic medical conditions and the socially isolated are particularly vulnerable. Air conditioning is the strongest protective factor against heat-related disorders. Heat waves cause disease indirectly, by aggravating chronic disorders, and directly, by causing heat-related illnesses (HRI). Classic HRI include skin eruptions, heat cramps, heat syncope, heat exhaustion and heat stroke. Heat stroke is a medical emergency characterised by hyperthermia and central nervous system dysfunction. Treatment includes immediate cooling and support of organ-system function. Despite aggressive treatment, heat stroke is often fatal and permanent neurological damage is frequent in those who survive. Heat related illness and death are preventable through behavioural adaptations, such as use of air conditioning and increased fluid intake. Other adaptation measures include heat emergency warning systems and intervention plans and environmental heat stress reduction. Heat related mortality is expected to rise as a consequence of the increasing proportion of elderly persons, the growing urban population, and the anticipated increase in number and intensity of heat waves associated with global warming. Improvements in surveillance and response capability may limit the adverse health conditions of future heat waves. It is crucial that health professionals are prepared to recognise, prevent and treat HRI and learn to cooperate with local health agencies.

Europe↗
PubMed2004

Risk assessment of exposure to volatile organic compounds in different indoor environments.

The lifetime cancer risks of exposure of cooks and food service workers, office workers, housewives, and schoolchildren in Hong Kong to volatile organic compounds (VOCs) in their respective indoor premises during normal indoor activities were assessed. The estimated cancer risk for housewives was the highest, and the second-highest lifetime cancer risk to VOC exposure was for the groups of food service and office workers. Within a certain group of the population, the lifetime cancer risk of the home living room was one to two orders of magnitude higher than that in other indoor environments. The estimated lifetime risks of food service workers were about two times that of office workers. Furthermore, the cancer risks of working in kitchen environments were approximately two times higher than the risks arising from studying in air-conditioned classrooms. The bus riders had higher average lifetime cancer risks than those travelling by Mass Transit Railway. For all target groups of people, the findings of this study show that the exposures to VOCs may lead to lifetime risks higher than 1 x 10(-6). Seven indoor environments were selected for the measurement of human exposure and the estimation of the corresponding lifetime cancer risks. The lifetime risks with 8-h average daily exposures to individual VOCs in individual environments were compared. People in a smoking home had the highest cancer risk, while students in an air-conditioned classroom had the lowest risk of cancer. Benzene accounted for about or more than 40% of the lifetime cancer risks for each category of indoor environment. Nonsmoking and smoking residences in Hong Kong had cancer risks associated with 8-h exposures of benzene above 1.8 x 10(-5) and 8.0 x 10(-5), respectively. The cancer risks associated with 1,1-dichloroethene, chloroform, methylene chloride, trichloroethene, and tetrachloroethene became more significant at selected homes and restaurants. Higher lifetime cancer risks due to exposure to styrene were only observed in the administrative and printing offices and air-conditioned classrooms. Higher lifetime cancer risks related to chloroform exposures were observed at the restaurant and the canteen.

Adult↗
PubMed1984

Bacterial air counts obtained with a centrifugal (RCS) sampler and a slit sampler--the influence of aerosols.

Samples of air collected from an air-conditioned hospital room with a 'Biotest RCS' centrifugal air sampler yielded (assuming a sampling rate of 40 l/min) air counts that were approximately twice those obtained with a modified conventional ' Casella ' slit sampler. However, for samples taken during the generation of an aerosol of spores of Bacillus globigii, the slit sampler gave counts that were apparently three- to tenfold higher than those with the centrifugal sampler. For a few minutes after switching off the nebulizer, higher counts were still obtained with the slit sampler, but then the centrifugal sampler again gave consistently higher counts. Our results illustrate that attempts to measure the number of bacteria in air are influenced by the size of the bacterial particles and the sampler that is used.

Aerosols↗
PubMed1988

Hormonal alterations in the lactating dairy cow in response to thermal stress.

The influence of acute exposure to thermal stress on the secretion of progesterone, estradiol, cortisol, and LH was monitored in 14 lactating Holstein cows. Eight cows were maintained throughout the summer in a refrigerated air-conditioned tie stall barn. An additional eight cows were maintained in outdoor corrals with access only to shade. Rectal temperatures and respiration rates of cows under heat stress conditions were elevated above the cows maintained under air conditioning. Cows in both environments exhibited similar serum concentrations of progesterone and estradiol throughout the estrous cycle. Serum cortisol concentrations were higher in heat-stressed cows compared to cows maintained under cooling. The number of LH pulses on d 5 of the estrous cycle was greatly reduced in the heat-stressed cows compared to the cows under cooling. No differences in the number of pulses of LH were observed on d 12 of the estrous cycle between cows in the two environments. Data suggest that heat stress can suppress anterior pituitary release of LH without having a measurable influence on ovarian steroid hormone secretion.

Animals↗
PubMed1979

Airway cooling. Stimulus for exercise-induced asthma.

Five patients were studied using a randomly assigned sequence of four inspired-air conditions during strenuous treadmill exercise for 10 min. The four inspired-air conditions were: (1) Cool, dry room air (CDA) at 23 degrees C with 3 mg of water and 7.3 cal of heat content/l, (2) over-saturated air (OSA) at room temperature containing 43 mg water and 16.3 cal/l, (3) hot, dry air (HDA) at 120 degrees C having 3 mg water and 24.4 cal/l, and (4) warm, humidified air (WHA) at 37 degrees C with 43 mg water and 34.7 cal/l. Using inspired-air CDA and OSA, all patients manifested exercise-induced asthma (EIA) while forced expiratory volume in 1 sec (FEV1) and maximal mid-expiratory flow (MMEF) decreased to an average of 81% and 63% of the baseline when breathing CDA and to 83% and 71% of the baseline when breathing OSA. With WHA, EIA was clearly prevented while the post-exercise FEV1 and MMEF were 101% and 103% of baseline, respectively. With HDA, the post-exercise FEV1 and MMEF were 95% and 86% of baseline, respectively. Analysis of variance revealed that the post-exercise pulmonary function changes had resulted solely from respiratory heat loss and not from water loss or from interaction of heat and water losses. These results indicate that exercise-induced asthma is associated with airway cooling incurred during exercise rather than airway dehydration.

Adolescent↗
PubMed2004

Mite and cat allergen exposure in Brazilian public transport vehicles.

BACKGROUND: Mites and pets are important sources of indoor allergens. OBJECTIVES: To determine Dermatophagoides pteronyssinus (Der p 1), Dermatophagoides farinae (Der f 1), and Felis domesticus (Fel d 1) allergen levels in buses and taxis and to evaluate the predominant allergen in each vehicle type. METHODS: Mite and cat allergens were measured using enzyme-linked immunosorbent assay in dust samples collected from upholstered seats in 60 natural-ventilation buses (NVBs), 60 artificial-ventilation buses (AVBs), and 60 taxis. Thirty dust samples from AVB air-conditioning filters were also included. RESULTS: Levels of Der p 1 and Der f 1 were significantly higher in AVBs than in NVBs, whereas Fel d 1 levels were not significantly different between bus types. No significant differences were found in mite allergen levels in various sites in both types of buses, whereas Fel d 1 levels were significantly higher in rear and middle seats than in front seats in NVBs. Mite and cat allergen levels in taxis were significantly higher in passenger's rear seats than in driver's seats. A high proportion of dust samples from the vehicles, especially AVBs (82% for Der p 1 and 58% for Der f 1) had sensitizing levels of mite allergens, whereas more than 60% of samples from all vehicles had sensitizing levels of Fel d 1 allergen. In AVBs, samples from seats showed significantly higher levels of mite and cat allergens than those from air-conditioning filters. CONCLUSIONS: Public transport vehicles constitute an important allergen reservoir for continuous contamination of the indoor environment.

Air Conditioning↗
PubMed2006

Association between PM2.5 and all-cause and specific-cause mortality in 27 US communities.

While fine mode particulate matter (PM(2.5)) forms the basis for regulating particles in the US and other countries, there is a serious paucity of large population-based studies of its acute effect on mortality. To address this issue, we examined the association between PM(2.5) and both all-cause and specific-cause mortality using over 1.3 million deaths in 27 US communities between 1997 and 2002. A two-stage approach was used. First, the association between PM(2.5) and mortality in each community was quantified using a case-crossover design. Second, meta-analysis was used to estimate a summary effect over all 27 communities. Effect modification of age and gender was examined using interaction terms in the case-crossover model, while effect modification of community-specific characteristics including geographic location, annual PM(2.5) concentration above 15 microg/m(3) and central air conditioning prevalence was examined using meta-regression. We observed a 1.21% (95% CI 0.29, 2.14%) increase in all-cause mortality, a 1.78% (95% CI 0.20, 3.36%) increase in respiratory related mortality and a 1.03% (95% CI 0.02, 2.04%) increase in stroke related mortality with a 10 microg/m(3) increase in previous day's PM(2.5). The magnitude of these associations is more than triple that recently reported for PM(10), suggesting that combustion and traffic related particles are more toxic than larger sized particles. Effect modification occurred in all-cause and specific-cause deaths with greater effects in subjects >or=75 years of age. There was suggestive evidence that women may be more susceptible to PM(2.5) effects than men, and that effects were larger in the East than in the West. Increased prevalence of central air conditioning was associated with a decreased effect of PM(2.5). Our findings describe the magnitude of the effect on all-cause and specific-cause mortality, the modifiers of this association, and suggest that PM(2.5) may pose a public health risk even at or below current ambient levels.

Aged↗
PubMed1999

Investigation of atmospheric, mechanical and other pressure effects influencing the levels of radon and radon progeny in buildings.

Real-time data measurement and analysis have identified a number of influences affecting the variability and accumulation of radon and its progeny in indoor air. Observed cycles in radon concentrations were shown to be related to the influence of air-conditioning and water-heated central heating systems. The cyclical pattern, related to operation of the air-condition system, showed radon levels almost four times lower during the period when the system was switched On than when it was Off. When the heating system was switched On the radon and radon progeny levels were 40% lower than when it was switched Off. Under both regimes, it was possible to establish the over-riding influence of meteorological factors by separating the recurring cyclical component from the relevant data set. The general or trend level of indoor radon was determined substantially by the prevailing atmospheric conditions.

Air Pollution, Indoor↗
PubMed1982

[Hygienic relevance of devices for indoor air treatment].

Shortcomings regarding design, construction, operation (including emissions), maintenance/repair and control of buildings with rooms for the accommodation of persons may be the reason to install air conditioning devices. According to manufacturers' data, such devices may be applied for various purposes, e.g. the creation of a defined air temperature or humidity, an increase of the supply of outdoor air, the cleaning and deodorization of indoor air or the alteration of the so-called electric climate of a room. The hygienic health evaluation of the different types of air conditioning devices should establish whether --there are aspects of health necessitating alterations of the microclimate of a room; --such alterations could be brought about in a more economic way by purely constructional or individual measures; --the function of individual apparatuses could be accomplished in a better way by replacing them by a larger device serving several rooms; --the operation of such devices may produce adverse health effects such as nuisance by noise, formation of undesirable gases (ozone), danger owing to non-adherence to electric safety rules; --there will be no damage to rooms and furniture, e.g. by water droplets. A look at a number of commercially available devices shows that they are generally dispensable. There are, however, special rare cases where the use of such devices may result in an improvement of the quality of indoor environments.

Air Conditioning↗
PubMed2000

Humidity and temperature profile in the nasal cavity.

OBJECTIVES/HYPOTHESIS: Adequate air conditioning in the nasal airways is mandatory for respiration and gas exchange in the lower respiratory tract. The aim of the present study was to measure relative humidity and temperature in the airstream at different sites within the nasal cavity for mapping of relative humidity and temperature in the upper airways. STUDY DESIGN: Intranasal relative humidity and temperature of 23 volunteers was measured during respiration at different locations in the nasal cavity. METHODS: The end-inspiratory temperature and humidity data, obtained with a miniaturized thermocouple and a capacitive humidity sensor, were determined. RESULTS: A high increase of humidity and temperature at the end of inspiration, in relation to the environmental conditions, was found in the anterior nasal segment. The further increase of both parameters between turbinate area and nasopharynx was less pronounced in spite of the longer distance. CONCLUSIONS: The anterior part of the nasal cavity contributes within a short nasal passage to air conditioning of inspired air.

Adult↗
PubMed1976

[Efficiency of heat exchanging equipment in a laboratory animal facility (author's transl)].

The efficiency of the so-called econovent heat exchanging equipment located in the Institute of Laboratory Animal Sciences, Faculty of Medicine, Kagoshima University, was measured as follows: The air velocity was decreased to about 64% of that with the fresh air ducts, but a sufficient air volume was supplied maintaining an air change of 12 times per hour or more. The efficiency of the econovent showed a little difference depending upon air conditioning systems. The average efficiencies were 81%, 75% and 76% for temperature, absolute humidity and enthalpy, respectively. The energy required for the air conditioning in this facility in September 1975 and January 1976 estimated by enthalpy hour almost agreed with that estimated using a calorie meter or steam meter. It was assumed that a total of 63% and 60% energy were saved in the cooling and heating seasons, respectively, using the econovent.

Air Conditioning↗
PubMed1978

[Does room air humidification prevent respiratory diseases in winter? An epidemiologic study on 1321 office workers].

An epidemiological study was carried out from January 15th to March 31st 1976 among 1321 clerical workers of the Administration of the Canton of Geneva. This study was intended to determine whether indoor humidification during winter prevents respiratory infections. The results obtained show that air-conditioning, in spite of an average relative humidity (RH) of 52%, has an unfavourable influence on respiratory infections which are significantly more numerous among people working in air-conditioned offices. Humidifiers did not have a significant influence on the incidence of respiratory diseases, but the trifling difference of average air humidity between offices equipped with humidifiers (RH:33%) and offices without humidifier (RH:30%) shows that these appliances, as at present commonly used, are inefficient. After a review of the literature on the subject, the authors reach the conclusion that no convincing evidence supports the theory of the effectiveness of indoor humidification in the prevention of respiratory diseases.

Adolescent↗
PubMed2005

[Progression of study on the health effects of indoor biological contaminants].

The use of HVAC (the heating, ventilation and air conditioning) system which leads to the inadequate circulation of indoor air, together with the popularization of family pets, creates an appropriate environment for survival and reproduction of air-borne microbes. Microbes with their toxin and allergen in air often adhere to saliva and particular matters, landing to the ground or floating in air for long time. Potential adverse health consequences may be led to subjects exposed to the biological contaminants. In particular, the disorders from the respiratory and allergic response were often reported. The progresses of studies on the biological contaminants during recent ten years were reviewed in the paper.

Air Conditioning↗
PubMed1989

Legionnaires' disease and the sick-building syndrome.

In October 1985, six cases of legionnaires' disease were associated with a police headquarters building. Four were amongst staff who worked in or visited the communications wing of the headquarters and two cases occurred in the local community. A case-control study implicated the operations room of the communications wing as the main area associated with infection. This wing was air-conditioned and smoke tracer studies showed that drift from the exhaust as well as from the base of the cooling tower entered the main air-intake which serviced the air-conditioning system. Legionella pneumophila serogroup 1 subgroup pontiac was isolated from water and sludge in the cooling tower pond. Contaminated drift from the top of the cooling tower was probably responsible for the two community cases. An additional discovery was that symptoms suggestive of the sick-building syndrome were associated with working in this wing.

Adult↗
PubMed2002

Determining the frequency of open windows in motor vehicles: a pilot study using a video camera in Houston, Texas during high temperature conditions.

Researchers have developed a variety of computer-based models to estimate population exposure to air pollution. These models typically estimate exposures by simulating the movement of specific population groups through defined microenvironments. Exposures in the motor vehicle microenvironment are significantly affected by air exchange rate, which in turn is affected by vehicle speed, window position, vent status, and air conditioning use. A pilot study was conducted in Houston, Texas, during September 2000 for a specific set of weather, vehicle speed, and road type conditions to determine whether useful information on the position of windows, sunroofs, and convertible tops could be obtained through the use of video cameras. Monitoring was conducted at three sites (two arterial roads and one interstate highway) on the perimeter of Harris County located in or near areas not subject to mandated Inspection and Maintenance programs. Each site permitted an elevated view of vehicles as they proceeded through a turn, thereby exposing all windows to the stationary video camera. Five videotaping sessions were conducted over a two-day period in which the Heat Index (HI)-a function of temperature and humidity-varied from 80 to 101 degrees F and vehicle speed varied from 30 to 74 mph. The resulting videotapes were processed to create a master database listing vehicle-specific data for site location, date, time, vehicle type (e.g., minivan), color, window configuration (e.g., four windows and sunroof), number of windows in each of three position categories (fully open, partially open, and closed), HI, and speed. Of the 758 vehicles included in the database, 140 (18.5 percent) were labeled as "open," indicating a window, sunroof, or convertible top was fully or partially open. The results of a series of stepwise linear regression analyses indicated that the probability of a vehicle in the master database being "open" was weakly affected by time of day, vehicle type, vehicle color, vehicle speed, and HI. In particular, open windows occurred more frequently when vehicle speed was less than 50 mph during periods when HI exceeded 99.9 degrees F and the vehicle was a minivan or passenger van. Overall, the pilot study demonstrated that data on factors affecting vehicle window position could be acquired through a relatively simple experimental protocol using a single video camera. Limitations of the study requiring further research include the inability to determine the status of the vehicle air conditioning system; lack of a wide range of weather, vehicle speed, and road type conditions; and the need to exclude some vehicles from statistical analyses due to ambiguous window positions.

Air Movements↗