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PubMed1994

[Acoustic implications of the use of air technology designs in the hospital--a case report and its consequences].

An undesirable side-effect of the operation of air conditioners in the hospital are acoustic emissions which can propagate as structure-borne noise or airborne noise in sick-rooms and function rooms. Despite useful information provided in DIN 1946 as well as in other relevant documents and legal statutes on restricting the acoustic emissions caused by air conditioning equipment, substantial noise phenomena are sometimes experienced in practice because of negligence in project engineering, installing and acceptance procedures. The air conditioning system of an ophthalmic hospital, exposing several rooms accommodating tumour patients of a Clinic of Radiology to substantial noise was studied to outline the problems involved in thresholds and indicative figures of noise comprising an essential low-frequency share as well as their particular annoying effects. It is recommended that the hospital hygienist should require the manufacturer and the fitter of an air conditioning system to present a special noise control certificate. The results of the investigation presented also serve to discuss hospital-specific and subject-related factors which can moderate the noise sensation of patients in threshold-relevant terms.

Air Conditioning↗
PubMed2005

Physiological measurements from native and transplanted mussel (Mytilus galloprovincialis) in the canals of Venice. Survival in air and condition index.

The Venice Lagoon has been the focus of many environmental studies due to its heavy contaminant load derived from a variety of sources, including industrial activity, oil tanker traffic, and waste runoff from the mainland. In recent years, there has been increasing concern about water quality in the urban areas of Venice related to the discharge of untreated sewage directly into canals, adding to the pollutant load already existing in these areas. One way of gauging the impact of these chemicals is monitoring the local fauna. In the search for good indicators of water quality in the Venice urban area, two physiological indices for mussels-survival in air and condition index-have been evaluated. In 2002, a seasonal study was undertaken; mussels (Mytilus galloprovincialis) were collected in three sites located in the canals of the city and a clean reference site. At the same time, two transplantation experiments were performed, deploying farmed mussels for 1,2, 4, and 12 weeks in the historic centre of Venice and also at a reference site. Data from survival in air test and the condition index of native and transplanted mussels are reported. The results suggest an impact of the complex mixture of pollutants on mussel health status. Both native mussels and those transplanted to the urban area showed reduced survivability in air and decreased condition index values, indicating a less healthy status in animals from the canals of the city. Data are discussed in relation to pollutant bioaccumulation.

Air↗
PubMed2001

Degradation of 2,4,6-trichlorophenol (2,4,6-TCP) by co-immobilization of anaerobic and aerobic microbial communities in an upflow reactor under air-limited conditions.

The co-immobilization and the culture of anaerobic and aerobic communities was tested for the mineralization of 2,4,6-trichlorophenol (2,4,6-TCP). At first, the anaerobic microorganisms (aggregated into granules) were cultivated in an upflow anaerobic sludge blanket (UASB) reactor, in a continuous mode, with glucose, propionate, acetate (COD loading rate = 0.5-2.0 g COD/l per day, ratio 1:1:1) and 2,4,6-TCP (2,4,6-TCP loading rate = 25-278 micromol/l per day) as substrates. 2,4,6-TCP was degraded into 2,4-DCP and 4-CP, but it was not mineralized because of the low degradation rates of 4-CP. Furthermore, the highest loading rates of 2,4,6-TCP (>126 micromol/l per day) caused the inhibition of the strains degrading the propionate. The granules were therefore tested in association with the aerobic community. They were immobilized in kappa-carrageenan/gelatin [2% (w/w) of each polymer] gel beads and cultivated in a reactor, on their own (to test the influence of the gel), and then with the aerobic community, under anaerobic and air-limited conditions, respectively. The results showed that (1) the gel did not influence the activity of the granules, (2) the anaerobic and aerobic communities could be easily co-immobilized in gel beads and cultivated in a reactor, (3) the mineralization of 2,4,6-TCP (2,4,6-TCP loading rate = 10-506 micromol/l per day), its intermediates of degradation and the other substrates [glucose + acetate + propionate (ratio 1:1:1) = COD loading rate = 500 mg COD/l per day] could be obtained under air-limited conditions if the culture parameters were strictly controlled [airflow = 36-48 vvd (volume of air/volume of liquid in the reactor per day), pH value at around 7.5]. Finally, the gel did not retain its structure during the whole culture (263 days) in the air-limited reactor, but the anaerobic and aerobic communities retained their activities and worked together for the mineralization.

Bacteria, Aerobic↗
PubMed1990

Successful chemotherapy of experimental neuroendocrine lung tumors in hamsters with an antagonist of Ca2+/calmodulin.

The chemotherapeutic effect of B859-35, the (-)-enantiomer of dihydropyrine 3-methyl-5-3-(4,4-diphenyl-1-piperidinyl)-propyl-1,4-dihydro-2,6-dimethy l-4- (3-nitrophenyl)-pyridine-3,5-dicarboxylate-hydrochloride (niguldipine), was tested on tumors induced in Syrian golden hamsters by N-nitrosodiethylamine (DEN). Peripheral pulmonary adenomas/adenocarcinomas were induced in hamsters maintained under ambient air conditions by multiple s.c. injections of DEN for 20 weeks. We have reproducibly shown that within this time interval lung adenomas develop in a significant number of the animals. The carcinogen treatment was discontinued at this point and one group of these hamsters was given B859-35 intragastrically 5 days/week for 20 weeks while the second group of such tumor-bearing hamsters were kept for an identical time interval without further treatment. Neuroendocrine lung tumors were induced in hamsters maintained in an atmosphere of 60% O2 by multiple s.c. injections of DEN for 8 weeks. We have reproducibly shown that within this short time interval neuroendocrine lung tumors develop in a significant number of the animals. The carcinogen treatment was discontinued at this point and the animals were returned to ambient air conditions. One group of these tumor-bearing hamsters was then given B859-35 intragastrically 5 days/week for 20 weeks while a second group of these hamsters was kept untreated for an identical time interval. A control group was given s.c. injections of saline for 20 weeks under ambient air conditions. A dramatic and selective anticarcinogenic effect of B859-35 was observed on the neuroendocrine lung tumors and nasal cavity tumors induced by DEN/hyperoxia while tumors of larynx/trachea were not affected. B859-35 had no effect on peripheral adenomas/adenocarcinomas, nasal cavity tumors, papillary polyps of larynx/trachea, or liver tumors induced by DEN under ambient air conditions.

Animals↗
PubMed1976

Distribution of waste anesthetic gases in the operating room air.

Epidemiologic and animal studies identify a strong relationship between chronic exposure to anesthetic gases and health hazards. Efforts to reduce exposure of personnel require an understanding of the distribution of anesthetic waste gases in the operating room air. Concentrations of nitrous oxide and halothane were measured at numerous stations throughout an operating room and a delivery room in the absence of personnel. Air conditioning flow rates and flow patterns were varied, as was the height of the anesthetic gas source. Air flow patterns were found to dominate the anesthetic gas distribution, while buoyancy effects were negligible. Venting waste gases at the floor does not significantly reduce exposure of personnel. Areas of high concentration were observed; their occurrences and locations varied strongly with air flow patterns. The exhaust grille is the best location for a single measurement of the average room concentration. Recirculating air-conditioning systems reduce energy costs; however, only the non-recirculating portion of the air exchanges reduces waste gas concentrations.

Air↗
PubMed1986

Postexertional airway rewarming and thermally induced asthma. New insights into pathophysiology and possible pathogenesis.

To determine if postexercise thermal events play a role in exercise-induced asthma (EIA), nine normal and eight asthmatic subjects on three occasions exercised while they inhaled frigid air. During the recovery period, either cold air, air at room temperature and humidity, or air at body conditions was administered in a random fashion. On a fourth occasion, body-condition air was given during exercise. Pulmonary mechanics were measured before and after each challenge. No changes in mechanics developed when air at body conditions was inhaled during exercise, however, increasing the heat content of the air during recovery produced progressively greater obstruction in both groups. On a separate occasion, seven asthmatics hyperventilated frigid air and either recovered spontaneously or had their ventilation slowly reduced. Controlling ventilation markedly attenuated the obstructive response. These data demonstrate that the severity of EIA is dependent not only on airway cooling but also upon the rapidity and magnitude of airway rewarming postchallenge.

Adult↗
PubMed2001

Heat and water rate transfer processes in the human respiratory tract at various altitudes.

The process of the respiratory air conditioning as a process of heat and mass exchange at the interface inspired air-airways surface was studied. Using a model of airways (Olson et al., 1970) where the segments of the respiratory tract are like cylinders with a fixed length and diameter, the corresponding heat transfer equations, in the paper are founded basic rate exchange parameters-convective heat transfer coefficient h(c)(W m(-2) degrees C(-1)) and evaporative heat transfer coefficient h(e)(W m(-2)hPa(-1)). The rate transfer parameters assumed as sources with known heat power are connected to airflow rate in different airways segments. Relationships expressing warming rate of inspired air due to convection, warming rate of inspired air due to evaporation, water diffused in the inspired air from the airways wall, i.e. a system of air conditioning parameters, was composed. The altitude dynamics of the relations is studied. Every rate conditioning parameter is an increasing function of altitude. The process of diffusion in the peripheral bronchial generations as a basic transfer process is analysed. The following phenomenon is in effect: the diffusion coefficient increases with altitude and causes a compensation of simultaneous decreasing of O(2)and CO(2)densities in atmospheric air. Due to this compensation, the diffusion in the peripheral generations with altitude is approximately constant. The elements of the human anatomy optimality as well as the established dynamics are discussed and assumed. The square form of the airways after the trachea expressed in terms of transfer supposes (in view of maximum contact surface), that a maximum heat and water exchange is achieved, i.e. high degree of air condition at fixed environmental parameters and respiration regime.

Altitude↗
PubMed1999

Indoor air quality at the Correr Museum, Venice, Italy.

Two multidisciplinary field surveys, one in winter and the other in summer have monitored the indoor microclimate, air pollution, deposition and origin of the suspended particulate matter and microorganisms of the Correr Museum, Venice. In addition, this study was focused to identify the problems caused by the heating and air conditioning system (HAC) and the effects due to the presence of carpets. Heating and air conditioning systems (HACs), when chiefly designed for human welfare, are not suitable for conservation and can cause dangerous temperature and humidity fluctuations. Improvements at the Correr Museum have been achieved with the assistance of environmental monitoring. The carpet has a negative influence as it retains particles and bacteria which are resuspended each time people walk on it. The indoor/outdoor pollutants ratio is greater in the summertime, when doors and windows are more frequently open to allow for better ventilation, illustrating that this ratio is mainly governed by the free exchange of the air masses. The chemical composition, size and origin of the suspended particulate matter have been identified, as well as the bacteria potentially dangerous to the paintings. Some general suggestions for improving indoor air quality are reported in the conclusions.

Aerosols↗
PubMed2001

Metropolitan home living conditions associated with indoor endotoxin levels.

BACKGROUND: Household endotoxin exposure in allergy and asthma has been gaining attention for its dual potential to exacerbate these conditions in individuals with established disease and to abrogate atopy before disease onset. OBJECTIVE: We sought to better understand the home environmental and lifestyle factors influencing house dust endotoxin levels. METHODS: From the homes of 86 infants with wheeze in metropolitan Denver, Colorado, house dust endotoxin (detected with a standardized Limulus Amebocyte Lysate assay) and common indoor allergen (Fel d 1, Can f 1, Der p 1, Der f 1, and Bla g 1) contents were quantified. Comprehensive home environment and lifestyle questionnaires were completed during home visits by trained study staff and parents. RESULTS: House dust endotoxin levels were associated with only 2 home environmental features: animals in the home and the presence of central air conditioning. The strongest positive associations were found with animals in the home. Interestingly, the homes without cats or other animals revealed a negative correlation between house dust Fel d 1 and endotoxin (P =.03). Central air conditioning, especially during months of typical use, was associated with lower house dust endotoxin levels. No significant associations between house dust endotoxin levels and home dampness, number of household inhabitants or young children, cleaning frequency, or presence of tobacco smokers in the home were found. CONCLUSIONS: Indoor endotoxin exposure can be increased by the presence of animals in the home and decreased with central air conditioning. In some homes without animals, where allergen exposure adequate for sensitization still occurs, there are lower levels of house dust endotoxin. Therefore in homes without animals, factors that influence allergen and endotoxin levels in house dust probably differ. Households with detectable allergen levels but low endotoxin levels may provide a predisposing environment for animal allergen sensitization.

Air Conditioning↗
PubMed1980

Hypersensitivity pneumonitis and Legionnaires' disease.

Four outbreaks of Legionnaire's disease (LD) and numerous instances of hypersensitivity pneumonitis (HP) have been associated with contaminated water in air-conditioning and cooling tower systems. The present study was carried out to determine if antibody to Legionella pneumophilia (LP) could be detected in the serums of persons with HP related to air-conditioning and cooling tower systems, thus suggesting a possible relationship between the 2 diseases. Serums from 209 persons with suspected or confirmed HP were examined for antibody to LP by the microagglutination method. The results of only 3 serum tests were positive; these serums were from persons with respiratory symptoms suggestive of HP from air-conditioning and cooling tower systems, but who lacked clinical and laboratory confirmation of the disease. The results of all serum tests from confirmed cases of HP were negative. The results indicate that there probably is no association between the organisms causing LD and those associated with HP.

Adolescent↗
PubMed2004

Summary of human responses to ventilation.

UNLABELLED: It is known that ventilation is necessary to remove indoor-generated pollutants from indoor air or dilute their concentration to acceptable levels. But as the limit values of all pollutants are not known the exact determination of required ventilation rates based on pollutant concentrations is seldom possible. The selection of ventilation rates has to be based also on epidemiological research, laboratory and field experiments and experience. The existing literature indicates that ventilation has a significant impact on several important human outcomes including: (1) communicable respiratory illnesses; (2) sick building syndrome symptoms; (3) task performance and productivity, and (4) perceived air quality (PAQ) among occupants or sensory panels (5) respiratory allergies and asthma. In many studies, prevalence of sick building syndrome symptoms has also been associated with characteristics of HVAC-systems. Often the prevalence of SBS symptoms is higher in air-conditioned buildings than in naturally ventilated buildings. The evidence suggests that better hygiene, commissioning, operation and maintenance of air handling systems may be particularly important for reducing the negative effects of HVAC systems. Ventilation may also have harmful effects on indoor air quality and climate if not properly designed, installed, maintained and operated. Ventilation may bring indoors harmful substances or deteriorate indoor environment. Ventilation interacts also with the building envelope and may deteriorate the structures of the building. Ventilation changes the pressure differences across the structures of building and may cause or prevent infiltration of pollutants from structures or adjacent spaces. Ventilation is also in many cases used to control the thermal environment or humidity in buildings. The paper summarises the current knowledge on positive and negative effects of ventilation on health and other human responses. The focus is on office-type working environment and residential buildings. PRACTICAL IMPLICATIONS: The review shows that ventilation has various positive impacts on health and productivity of building occupants. Ventilation reduces the prevalence of airborne infectious diseases and thus the number of sick leave days. In office environment a ventilation rate up to 20-25 L/s per person seem to decrease the prevalence of SBS-symptoms. Air conditioning systems may increase the prevalence of SBS-symptoms relative to natural ventilation if not clean. In residential buildings the air change rate in cold climates should not be below app. 0.5 ach. Ventilation systems may cause pressure differences over the building envelope and bring harmful pollutants indoors.

Air Conditioning↗
PubMed2001

Kappa-carrageenan/gelatin gel beads for the co-immobilization of aerobic and anaerobic microbial communities degrading 2,4,6-trichlorophenol under air-limited conditions.

Alginate and kappa-carrageenan gels were tested as bead materials for the co-immobilization of anaerobic and aerobic microorganisms for the mineralization of 2,4,6-trichlorophenol under air-limited conditions. Chemical, mechanical and thermal culture constraints were pre-defined and the gel resistances were established. Alginate was quickly eliminated because of its chemical instability in the culture media. In anaerobic conditions, the microorganisms transformed the substrates into CH4 and CO2. The kappa-carrageenan gel did not enable these gases to diffuse. They remained as bubbles in the core of the beads and made the beads float. Gelatin was added to kappa-carrageenan in order to change the carrier properties. No biogas bubbles appeared in the bead core during the cultures in anaerobic conditions and the beads reacted well to the culture conditions in the reactor. The co-immobilization of the anaerobic and aerobic microbial communities was successfully performed with the kappa-carrageenan/gelatin gel (2% (w/w) of each polymer). The biological activities, measured by the impedancemetry technique, were preserved in the beads.

Alginates↗
PubMed1979

Survey of operating room pollution within an N.H.S. district.

Pollution by waste anaesthetic gases was measured in all operating departments in a typical N.H.S. district. Methods were chosen to provide time-weighted average levels over the period of each operating session. The results showed that air-conditioning alone could not guarantee pollution levels below suggested maximum levels and that to meet those requirements air-conditioning plus scavenging was necessary. Background pollution levels were found to be representative of the personal exposure of nursing staff but approximated to only one third of the anaesthetists' personal exposure. Dental clinics presented special problems, namely the very high levels of pollution to which the dentist and his assistants were exposed.

Air Conditioning↗
PubMed1989

Building sickness, are symptoms related to the office lighting?

Office lighting has been suggested as one of the possible factors in producing 'building sickness'. Health questionnaires were completed by 106 out of 109 (97%) workers in six randomly sampled multi-occupied offices in each of two buildings, one air-conditioned and one naturally ventilated. There was a significantly higher prevalence of work-related headache and work-related lethargy in the air-conditioned building than in the naturally ventilated one. There was also less daylight in the air-conditioned building and lower mean luminance and illuminance of the work positions despite there being more lights on (p less than 0.01). The workers had a greater dislike of fluorescent lighting (p less than 0.01) and overall found the lighting to be less comfortable (p less than 0.01) and glare readings were higher. The workers perceived their control of lighting as poorer (p less than 0.001) and consequently there was less agreement about it (p less than 0.001). Those with work-related headache found the lighting less comfortable (p = 0.059) and perceived more glare (p less than 0.05). This study suggests the need to maximize the use of natural light from untinted windows, to reduce the impingement of fluorescent tubes on the line of sight and to return the control of levels of lighting to each individual worker.

Environment Design↗
PubMed2001

Investigation of the potential for radon mitigation by operation of mechanical systems affecting indoor air.

Mitigation of radon gas and radon progeny in buildings is based largely on reducing the pressure difference between the point of the radiation source and the point of entry to indoor air. This study identifies the influence of mechanical systems, of air-conditioning and 'wet' systems of central heating as potential remediation agents in the control of radon and progeny concentrations. Air-conditioning was found to reduce radon levels in a systematic way within a few hours of start-up, to a low fraction of the immediately preceding concentration. Central heating reduced the level by around 40% of the preceding high within a few hours of start-up. Importantly for health concerns, under operating conditions of both types of system the level of radon progeny was reduced to a greater extent than the radon progenitor.

Air Conditioning↗
PubMed2006

Air quality in passenger cars of the ground railway transit system in Beijing, China.

This study examined the concentrations of carbon monoxide, carbon dioxide, TVOC, TSP, PM(10), PM(2.5), PM(1), benzene, toluene and xylene in passenger cars of the Beijing Ground Railway Transit System (Line No. 13). This system connects the northern suburb and downtown, and is equipped with air-conditioned passenger cars. In-train air quality monitoring was performed in both summer (July and August) and winter (December). To obtain representative data, the sampling design considered both rush and regular hours, urban and suburban areas, as well as the number of passengers. Meanwhile, questionnaires were distributed to the passengers. The monitoring results indicated that, overall, the air quality in the passenger cars was acceptable with a few exceptions, which is consistent with the passengers' perception. Concentrations of some air pollutants showed significant seasonal variations and had the significant difference between rush hour and regular hour. Furthermore, the in-train air quality was greatly influenced by the number of passengers. This paper describes the experimental design, and presents the preliminary results.

Air↗
PubMedDate not supplied

Changes in airborne fungi from the outdoors to indoor air; large HVAC systems in nonproblem buildings in two different climates.

Little is known about the changes in occurrence and distribution of airborne fungi as they are transported in the airstream from the outdoor air through the heating, ventilation, and air conditioning (HVAC) system to the indoor air. To better understand this, airborne fungi were analyzed in the HVAC systems of two large office buildings in different climate zones. Fungal samples were taken in each of the walk-in chambers of the HVAC systems using a six-stage Andersen Sampler with malt extract agar. Results showed that fungal species changed with different locations in the HVAC systems. The outdoor air intake produced the greatest filtration effect for both the counts and species of outdoor air fungi. The colony forming unit (CFU) counts and species diversity was further reduced in the air directly after the filters. The cooling coils also had a substantial filtration effect. However, in room air the CFU counts were double and the mixture of fungal species was different from the air leaving the HVAC system at the supply air outlet in most locations. Diffusion of outdoor air fungi to the indoors did not explain the changes in the mixture of airborne fungi from the outdoor air to the indoor air, and some of the fungi present in the indoor air did not appear to be transported indoors by the HVAC systems.

Air Conditioning↗
PubMed1990

[Evaluation of humidifier units within the scope of room climate modification].

An analysis method was developed for detecting the biocides usually employed in German humidification units in air-conditioning plant to enable determination of air concentrations of methylisothiazalone often used in such plant (German trade names e.g. Kathon WT, Wacozid 3150, Lavisan Q). Results of measurements revealed great variations in isothiazolone concentrations in ambient indoor aerosols, the peak values being 3.4 micrograms/m3 air. The concentration of these compounds added to the water in the humidificator chambers was also measured in relation to the presence of microorganisms to find out the microbicidal action of the compounds. It was found that the isothiazolone concentrations varied greatly in course of time and that microbiology revealed in some cases a marked contamination of the water in the humidifiers with pathogens. Microbial analyses showed the presence of Legionella pneumophila and free amoeba, sometimes with very high aerobic colony counts. The measured data lead to the conclusion that it is possible that both the unsatisfactory hygienic status of many circulatory spray humidifiers and the exposure to the biocides contained in the humidifier fluids, may be responsible for some of the patterns of signs and symptoms known as "sick building" syndrome.

Air Conditioning↗