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Lung function of workers exposed to antigens from a contaminated air-conditioning system.
Following the manifestation of humidifier fever in a number of workers in a carpet yarn texturing plant, a comparative study was begun of a group of workers exposed to fungi from the air-conditioning system and a control group not so exposed. For both group of workers anamnestic data were collected, intracutaneous skin tests were performed, certain lung function parameters were determined, and the presence of antibodies to a number of antigens from the system was tested for. It was found that the group of exposed workers had a significantly higher rate of positive intracutaneous skin test than non-exposed workers. Additionally, their serology was more often positive. Both positive skin test and positive serology were more frequent in non-smokers than in smokers. A positive immediate skin reaction among exposed workers was found to correlate with an FEF25-75 reduction during the working week. A positive delayed skin reaction among exposed workers correlated with a lower FVC prior to the start of the working week than recorded for non-exposed workers. A positive serology in exposed workers did not correlate with a difference in lung function compared with non-exposed workers, nor was there a correlation with a change in lung function in the course of the working week. When humidifier fever is diagnosed, steps should be taken to reduce exposure. It would also appear desirable to keep exposed workers under medical observation and to monitor the subsequent development of their lung function.
[A simplified and quantitative method for culturing and isolating Legionella from air condition cooling waters].
OBJECTIVE: To establish simplified technique to investigate the distribution of Legionella from air condition cooling waters in a district in Shanghai. METHODS: Using simplified method to make GVPC agar plates; using candle jar to replace CO(2) incubator; initial identification was only relied on colony appearance but no growth on the blood agar plate; and a simple formula was used to quantify the Legionella in waters. RESULTS: From July 1997 to June 1999 in Luwan District Shanghai, the simplified methods were used to culture and isolate 185 Legionella strains from 371 water samples (47 fixed spots of hotels, markets, resident buildings, hospitals, subway stations, cinemas and stadiums), with a detection rate of 49.87% with highest at the subway stations (69.36%), which were significantly higher than repeated in the literature in this country and abroad. CONCLUSIONS: Simplified methods were established for culturing, isolating and quantifying Legionella. These methods had been used for 3 years to have got a high Legionella detection rate from the cooling waters. The high detection rate and quantity of Legionella in cooling waters of subway stations call for more attention to the fact that Legionellosis might exist in these waters.
Comparison of airborne fungi in evaporative cooled and air conditioned homes.
The evaporative cooler (EC) is commonly used during the warmer months in millions of homes in the desert regions of the Southwestern United States. In this investigation fungi isolated from EC homes were compared with recoveries from air conditioned (AC) homes. Aspergillus tamarii was more abundant in EC homes (P less than .05) whereas Penicillium spp. were more prevalent in AC homes (P less than .05). Fusarium was recovered only from EC homes. Overall, more fungi were isolated from EC homes than AC homes both in terms of total numbers of isolates and numbers of species recovered. The EC appears to provide a niche for allergenic fungi that may be transmitted into the home or business.
Emission modelling and validation of VOCs' source strengths in air-conditioned office premises.
An emission model for indoor volatile organic compounds (VOCs) based on mass balance considerations has been presented and validated under steady state conditions. Comparison were made for the measured and predicted concentrations of 37 selected VOCs and TVOC through a case intervention study on the filters of the ventilation system in a new commercial air-conditioned office building. The intervention involved replacing media filters with electronic and carbon filtration. TVOC and 37 compounds selected for their health and comfort impact, representation of major chemical classes that occur in indoor air and their utility as markers of pollution sources were studied. The concentration levels predicted by the model were compared with actual measurements. Twenty-five target compounds and the TVOC were adequately described by the model where the measured concentrations were in agreement with the predicted concentrations. Modeling of the remaining 12 compounds was found to be affected by the emission rates that were occupant related.
Changing microbial concentrations are associated with ventilation performance in Taiwan's air-conditioned office buildings.
UNLABELLED: Our study conducted serial environmental measurements in 12 large office buildings with two different ventilation designs to obtain airborne microbial concentrations in typical office buildings, and to examine the effects of occupant density, ventilation type and air exchange efficiency on indoor microbial concentrations. Duplicate samples of airborne fungi and bacteria, a total of 2477 measurements, were collected based on a scheme of conducting sampling three times a day for at least seven consecutive days at every study building. Air change rates (ACHs) were also estimated by tracer gas concentration decay method, and measured by continuous Multi-Gas monitor for each building. Most sampling sites were with total fungal and bacteria concentrations higher than 1000 CFU/m(3), an often-quoted guideline in earlier research. Significantly higher concentrations of fungi and bacteria, as well as higher indoor/outdoor (I/O) ratios across most groups of airborne microbes, were identified in buildings with fan coil unit (FCU) system than those with air-handling unit (AHU) system (Student's t test, P < 0.0001). Older buildings and higher air exchange rates were statistically associated with greater indoor bacteria levels in FCU ventilated buildings (R(2) = 0.452); a pattern not found in AHU buildings. Increasing ACH seemed to be the determinant factor for rising indoor fungal and Cladosporium concentrations in those FCU buildings (R(2) = 0.346; 0.518). Our data indicated that FCU ventilated buildings might have provided more outdoor matters into indoor environments through direct penetration of outdoor air. Results also demonstrated a quantitative association between rising numbers of occupants and increasing indoor levels of yeast in both FCU and AHU ventilated buildings. The regression model identified in this study may be considered a reference value for proposing an optimal ACH, while with adequate filtration of fresh air, as an effective strategy in lowering indoor microbial concentrations in air-conditioned buildings. PRACTICAL IMPLICATIONS: As control of indoor microbial contamination has become an increasing concern around the world, feasibility and effectiveness of adopting ventilation approach has attracted a significant interest. This field investigation demonstrated, quantitatively, critical variables to be taken into consideration while applying such a measure, including the kinds of microbes to be removed and the types of ventilation system already in place.
Aerial contamination of an air-conditioned bacteriology department and suggested remedy.
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Contribution of heating, ventilation, and air conditioning airflow and conversation to the ambient sound in a neonatal intensive care unit.
Sound reduction strategies in the neonatal intensive care unit (NICU) must focus on the sources of excessive sound. We studied the relative contribution of personnel conversation and heating, ventilation, and air conditioning (HVAC) airflow by measuring several parameters of sound during four environmental conditions: unaltered ambient sound, HVAC airflow off, HVAC airflow and conversation off, and conversation off. All measurements were decreased by interrupting HVAC airflow and conversation. The reduction was greater when conversation was stopped. The method of sound reduction did not change the frequency distribution of sound. Attention to personnel conversation may be effective in lowering sound exposure in the NICU. The contribution of HVAC airflow should be measured in new constructions and renovations.
[Pollution of operating room air by anesthetic gases in relation to the air conditioning method and anesthesia techniques].
Volatile anesthetics are suspected to cause various health risks even in subnarcotic concentrations (hepatotoxicity, mutagenicity, teratogenicity). Yet only for halothane a limit (MAK-value = 5 ppm) has been established for the entire FRG. In addition, in 1991 Hamburg and Schleswig-Holstein defined preliminary limits for isoflurane, enflurane and nitrous oxide. We analysed the pollution of operating-room air by narcotic gases in 20 hospitals of Niedersachsen. In several cases limits have been exceeded evidently. Reasons for high concentrations were: insufficient room ventilation, defective air-conditioning plants, technical defects (leakage) and high gas emission due to special techniques in anesthesia (bronchoscopy). In order to take care of personnel-health air concentration of anesthetic gases should be kept as low as possible by the help of sufficient room ventilation avoiding unnecessary emissions.
[Technical and hygienic examinations of operating rooms with conventional air conditioning systems].
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Air conditioning in dermatology.
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[Energy consequences of air flow direction in the air conditioning of office spaces].
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[Air conditioning with a high-performance HME (heat and moisture exchanger)--an effective and economical alternative to active humidifiers in ventilated patients. A prospective and randomized clinical study].
Heat and moisture exchangers (HME) are used as artificial noses for intubated patients to prevent damage resulting from dry and cold inspired gases. HME collect a large fraction of the heat and moisture of the expired air, adding them to the subsequent inspired breath. In a prospective clinical study the air conditioning capacity of a heated humidifier was compared with a hygroscopic HME. METHODS. The water content of the ventilated air of 49 intensive care patients requiring artificial ventilation with tidal volumes between 440 and 1,190 ml (mean 658 +/- 148 ml) was examined. Each patient was ventilated in sequence with an HME (DAR Hygrobac S) and a heated humidifier (Fisher & Paykel MR 630 B). The temperature of the air in the inspiratory limb was maintained at 34 degrees C. The water content of the ventilated air was determined under steady-state conditions directly at the tracheal tube or between tracheal tube and HME using a new, high-resolution humidity meter. The results were compared with the absolute water loss of the exhaled air at the gas outlet of the ventilator as an expression of the water loss from the lower airways. Airway resistance was calculated by a standard formula. The daily running costs for both HME and heated humidifier were estimated. RESULTS AND DISCUSSION. Moisture retention was equivalent in both the HME and the heated humidifier (33.7 +/- 1.85 bzw. 34.1 +/- 2.62 mgH2O/l). These data show that modern HMEs are able to maintain physiological air-conditioning even in long-term ventilated patients. The small increase in airway resistance associated with HMEs (3.1 +/- 2.5 mbar/l.s) has to be noted in difficult weaning procedures. Both labour and costs per day are significantly less with HMEs (8.60 vs. 21.70 DM).
An outbreak of Legionnaires' disease associated with a contaminated air-conditioning cooling tower.
In August and September 1978, an outbreak of Legionnaires' disease occurred in Memphis, Tennessee. Of the 44 ill, 39 had been either patients, employees, visitors, or passers-by at one Memphis hospital (Hospital A) during the 10 days before. Assuming an incubation period of between two and 10 days, the onset of cases correlated precisely with the use of Hospital A's auxiliary air-conditioning cooling tower. L. pneumophila was recovered from two samples of water from the tower. Infection appeared to have occurred both outside and within the hospital. A significant association was demonstrated between acquisition of Legionnaires' disease and prior hospitalization in those areas of Hospital A that received ventilating air from air intakes near the auxiliary cooling tower. Tracer-smoke studies indicated that contaminated aerosols from the tower could easily reach these air intakes, as well as the street below, where four passers-by had been before they contracted Legionnaires' disease. This represents a common-source outbreak in which the source of L. pneumophila infection and airborne transmission were identified.
Effects of anti-odor automobile air-conditioning system products on adherence of Serratia marcescens to aluminum.
Sixteen commercial products for use in automobile air-conditioning systems (ACS), most designated for abatement of malodors presumably of microbial origin, were examined for their potential to inhibit attachment and to detach cells of the Gram-negative bacterium Serratia marcescens on aluminum sections. Numbers of attached cells were appreciably reduced (>60%) following immersion in three alcohol-type and two acrylic-coating-type products. Several products had essentially no effect on the attached cells. Most of the products indicated for alleviation of associated microbial odors from ACS provided only short-term effects. When products were coated onto aluminum prior to exposure to the cells, water-insoluble coatings appeared to provide more consistent inhibition of primary adherence of S. marcescens. The differences in degrees of primary adherence of a selected strain of S. marcescens to variously treated aluminum provided a rapid and reproducible assessment of potential antimicrobial efficacy of ACS products.
Sterilization efficacy of ultraviolet irradiation on microbial aerosols under dynamic airflow by experimental air conditioning systems.
In order to know the sterilization efficacy of ultraviolet irradiation on microbial aerosols, the size and the weight of the aerosol particles were evaluated, and these were irradiated under dynamic air flow created by an experimental air conditioning system. The experimental apparatus consisted of a high efficiency particulate air (HEPA) filter, an aerosol generator, spiral UV lamps placed around a quart glass tube, an Andersen air sampler and a vacuum pump. They were connected serially by stainless steel ducts (85 mm in diameter, 8m in length). Six types of microbial aerosols generated from an ultrasonic nebulizer were irradiated by UV rays (wavelength 254nm, mean density 9400 microW/cm2). Their irradiation time ranged from 1.0 to 0.0625 seconds. The microbial aerosols were collected onto the trypticase soy agar (TSA) medium in the Andersen air sampler. After incubation, the number of colony forming units (CFU) were counted, and converted to particle counts. The diameter of microbial aerosol particles calculated by their log normal distribution were found to match the diameter of a single bacteria cell measured by a microscope. The sterilization efficacy of UV in standard airflow conditions (0.5 sec. irradiation) were found to be over 99.5% in Staphylococcus aureus, Staphylococcus epidermidis, Serratia marcescens, Bacillus subtilis (vegetative cell) and Bacillus subtilis (spore) and 67% in Aspergillus niger (conidium). In A. niger, which was the most resistant microbe to UV irradiation, the efficacy rose up to 79% when irradiated for 1.0 sec., and it was observed that the growth speed of the colonies was slower than that of the controls. It was thought that UV rays caused some damage to the proliferation of A. niger cells.
Exercise-induced bronchoconstriction in adults with asthma--comparison between running and cycling and between cycling at different air conditions.
The bronchial response to cycling and running was compared in six adult asthmatic persons. The effects of different air conditions during cycling regarding the induction of bronchoconstriction was studied. The exercise consisted of 6 minutes' work at an intensity of 80-85% of maximal heart rate. Heart rate, oxygen consumption and ventilation were measured to check that the exercise level was the same in all tests. Peak expiratory flow (PEF) was used to test for bronchoconstriction. Bicycling and treadmill running were performed under indoor conditions and bicycling while breathing cold, dry air (-18 degrees C) and room-tempered humid air (60% RH), respectively. No difference in bronchoconstriction was found between cycling and running under indoor conditions. However, bicycling exercise with inhalation of cold dry air provoked more bronchoconstriction than when inhalating humid air (PEF reductions of 19.4+/-6% and 6.1+/-2%, respectively). No differences were found between the exercise modes in heart rate, oxygen consumption, ventilation per minute, respiratory rate, carbon dioxide elimination or subjective ratings of perceived exertion and breathlessness. It is concluded that it is not the type of exercise, but the ventilation demand and humidity of the inspired air that are the main determinants of the occurrence and degree of bronchoconstriction.