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At least 19 recordsLinked to original sources
PubMed1992

[Comparison of lung function parameters in healthy non-smokers following exertion in urban environmental air and in air-conditioned inside air].

This study examines the question whether young healthy nonsmokers show differences in parameters of lung function after having been exposed to exercise in city air and to the same exercise in air-conditioned room air. For this purpose 16 young nonsmokers of age 20-39 years (10 men: 26.6 +/- 5.2, 6 women: 22.2 +/- 1.4) exercised maximally once on a bicycle ergometer in city air for 8 minutes and 48 hours later in air-conditioned room air on the same ergometer also for 8 minutes. The forced vital capacity, the forced expiratory volume in 1 second (FEV1) and peak expiratory flow rates were determined before exercise, immediately after, and after the rest of 10, 30, 60, and 120 minutes. The following results were obtained: 1. In city air the continuously recorded concentrations of NO2 showed a mean value (+/- 1 SD) of 71.6 micrograms/m3 (+/- 23.2) and thus about 10 times higher than in air-conditioned room air, where the mean value of NO2 was 7.5 micrograms/m3 (+/- 3.5). 2. 10, 30, 60, and 120 minutes after exercise in city air the mean FEV1 values were about 2.5-3% lower than in room air. Even though these differences were small, they were significant (10 minutes after exercise p = 0.006, 30 minutes p = 0.011, 60 minutes p = 0.025, and 120 minutes p = 0.016). 3. The FEV1 differences were more pronounced in males. The males were, due to conditions beyond our control, exposed to higher NO2 and NO concentrations in city air than females.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1981

[Distribution of environmental temperature and relative humidity according to the number of conditioned air changes in laboratory animals rooms].

The relation of the rate of circulating air change to room temperature and relative humidity in animal quarters with a central air-conditioning system during heating and cooling seasons was investigated, with the results as follows: During the period of heating, the ambient temperature generally rose with a fall of relative humidity as the number of conditioned air changes per hour was increased. Vertical differences in temperature and humidity between levels of 0.5 and 1.5 m above the floor also diminished with increasing air change rate. This tendency was more conspicuous in small animals rooms with outer walls facing north and west. With increasing rate of air changes, the room temperature was prone to decline and the relative humidity to rise during the period of cooling. There were less vertical differences in temperature and humidity during this period. The velocity of air circulation within the animal quarters and its variations tended to increase progressively with increasing rate of ventilation, though the changes were modest.

Air Conditioning↗
PubMed1975

Airborne infection in a fully air-conditioned hospital. I. Air transfer between rooms.

Measurements have been made of the extent of air exchange between patient rooms in a fully air-conditioned hospital using a tracer-gas method. When the rooms were ventilated at about six air changes per hour, had an excess airflow through the doorway of about 0.1 m.3/sec. and the temperature difference between rooms and corridor was less than 0.5 degrees C., concentrations of the tracer in rooms close to that in which it was being liberated were 1000-fold less than that in the source room. This ratio fell to about 200-fold in the absence of any excess airflow through the doorways. Considerable dilution took place along the corridors so that the concentration fell by around 10-fold for every 10 m. of corridor.

Air Conditioning↗
PubMed2004

Asbestos exposure among Seoul metropolitan subway workers during renovation of subway air-conditioning systems.

Air quality in underground spaces has seldom been evaluated in Korea. Accordingly, the current study recently evaluated asbestos exposure among Seoul metropolitan subway workers during the renovation of the subway's air-conditioning system. To identify possible routes of asbestos exposure, suspected sources, including gaskets, ceiling boards, ceiling materials, and dust settled inside ducts, were all sampled. Personal air samples were also taken to evaluate any asbestos exposure during the renovation. The asbestos fibers found in the samples were analyzed using a transmission electron microscope (TEM) equipped with an energy dispersive X-ray analyzer (EDX). Twelve out of eighteen bulk samples contained asbestos, the majority of which was chrysotile fibers. Asbestos was detected in 9 out of 72 personal air samples and the level ranged from 0.003 to 0.02 fibers/cm(3). While asbestos levels were below Korean occupational limit of 2 fibers/cm(3), they were still detectable and therefore further monitoring would be appropriate.

Air Conditioning↗
PubMedDate not supplied

Human health and air conditioning systems.

In air-conditioned buildings indoor air quality is closely dependent on the efficiency of air-conditioning and humidifier systems since these systems provide a suitable environment for the proliferation of microorganisms. Pollutants released by microorganisms are termed 'bioaerosols' and may be spread in the indoor environment through the air-conditioning system. Moreover, the tightening of the buildings in which central air-conditioning systems are usually located increases the levels of indoor pollutants. Both hypersensitivity and infectious diseases are associated with bioaerosol exposure, whereas the sick building syndrome (a complex of symptoms described among workers in modern office buildings which are hermetically sealed and mechanically ventilated) is very unlikely to have a bioaerosol component.

Aerosols↗
PubMed1988

The effect on airway function of inspired air conditions after isocapnic hyperventilation with dry air.

The magnitude of postexercise or posthyperventilation bronchoconstriction in patients with asthma is related to the temperature and the water content of the inspired air during the exercise or hyperventilation period. Recent studies have suggested that the inspired air conditions during recovery from exercise may also be important in determining the magnitude of postexercise airway narrowing. In the present study, normal subjects (n = 8) and patients with asthma (n = 12) were studied on separate days. On day 1 the subjects performed isocapnic hyperventilation with warm dry air and recovered breathing warm dry air. On the second day, an identical warm dry air challenge was administered, but recovery occurred while they were breathing warm humid air. There was no significant bronchoconstriction in the normal subjects, irrespective of the inspired air conditions during recovery. The patients with asthma showed greater bronchoconstriction during recovery in warm, humid air (maximal decrease in FEV1 31% +/- 17%) than in dry air (maximal decrease in FEV1 19% +/- 20%; p less than 0.05). These results suggest that the inspired air condition during recovery from isocapnic hyperventilation of dry air is also a determinant of the magnitude of the bronchoconstrictor response.

Adult↗
PubMed1992

[Legionella and other bacteria in air humidifiers and cooling systems of air conditioning units--a survey].

Air humidifiers using cold water and cooling towers of air-conditioning systems provide the best settings for the growth of bacteria. Hence, we investigated 90 water samples for humidifiers and 15 water samples from cooling towers of hospitals, authorities, schools, and factories. The colony forming units/ml at 20 degrees C and 36 degrees C, the biological activity of added biocidal substances, and the occurrence of legionella were determined. About 90 percent of the samples showed no activity of the biocidal substance added, suggesting the uselessness of such substances. Furthermore, they exercised neither an influence on the CFU of the water samples nor on the occurrence of legionella. Legionella were isolated in 7 per cent of the humidifiers investigated, in 3 per cent of air conditioned buildings, respectively. 13 per cent of the cooling towers contained legionella. The risk of infection by air conditioning systems, humidifiers, cooling towers, and other emitters of infections agents should be controlled by the public health service.

Air Conditioning↗
PubMedDate not supplied

Experimental studies of the human nasal air-conditioning capacity.

Nasal air-conditioning capacity was measured in human subjects by a method reported in 1977, which enables determinations to be made in each nasal cavity separately without introducing a foreign occluding structure between the soft palate and the posterior pharyngeal wall. The enthalpy for vaporization and for the warming of the air and the water vapour can be calculated separately. The error due to the escape of air from the lower airways, measured with both carbon dioxide and helium as tracer, was found usually to be about 1%, but sometimes greater. By varying the air flow through the relevant nasal cavity it was found that the maximum air conditioning capacity had still not been reached at 7 l/min. However, the patient suffered discomfort at flows in excess of 5 l/min. The nasal air conditioning capacity was lower at night than in the daytime. The total enthalpy and vaporization decreases with age.

Aging↗
PubMed1997

[Sanitary impact of air conditioning: what is the relation to sick building syndrome?].

Modern architecture is creating air-conditioned offices in our society. Various diseases have been associated with conditioned air exposure, and building-related diseases are distinct from sick building syndrome (SBS). Building-related diseases have a well-characterized aetiology, essentially infectious, compared to SBS, where the aetiology is not clear. This paper reviews these syndromes, their aetiologies and their discussion in order to treat and prevent their expression. Progress has been made in the conception of air-conditioning systems. Prevention of these syndromes is based on conception and cleaning of these systems, which allows the use of air-conditioning without any major sanitary problem.

Air Conditioning↗
PubMed2001

Capability of air filters to retain airborne bacteria and molds in heating, ventilating and air-conditioning (HVAC) systems.

The capability of air filters (filterclass: F6, F7) to retain airborne outdoor microorganisms was examined in field experiments in two heating, ventilating and air conditioning (HVAC) systems. At the beginning of the 15-month investigation period, the first filter stages of both HVAC systems were equipped with new unused air filters. The number of airborne bacteria and molds before and behind the filters were determined simultaneously in 14 days-intervals using 6-stage Andersen cascade impactors. Under relatively dry (< 80% R. H.) and warm (> 12 degrees C) outdoor air conditions air filters led to a marked reduction of airborne microorganism concentrations (bacteria by approximately 70% and molds by > 80%). However, during long periods of high relative humidity (> 80% R. H.) a proliferation of bacteria on air filters with subsequent release into the filtered air occurred. These microorganisms were mainly smaller than 1.1 microns therefore being part of the respirable fraction. The results showed furthermore that one possibility to avoid microbial proliferation is to limit the relative humidity in the area of the air filters to 80% R. H. (mean of 3 days), e.g. by using preheaters in front of air filters in HVAC-systems.

Air Conditioning↗
PubMed1989

[Hygienic evaluation of substrata of contamination of ventilation and air conditioning systems].

Modern ventilation and air conditioning systems are complex technological objects in environment which can be sources of health-hazardous factors, including biological ones. Ventilation and air conditioning contact systems with water and partial air recirculation have construction prerequisites for environmental accumulation and dispersal of organic substances of microorganism and anthropogenic origin. Pollution substrates of inner surfaces of the above systems contain specific antigens causing immune response in persons working in air-conditioned premises.

Air Conditioning↗