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PubMed1984

Effect of alpha-adrenergic blockade on exercise-induced asthma and conditioned cold air.

Cooling and drying of the intrapulmonary airways have been shown to be important stimuli for the development of bronchospasm induced by exercise and isocapnic cold air hyperventilation. It has also been suggested that alpha-adrenergic receptor activity is increased at lower temperatures. To evaluate the role of alpha-adrenergic activity in the development of bronchoconstriction during airway cooling, we examined the effects of alpha-adrenergic blockade with phentolamine on bronchospasm induced by exercise and isocapnic cold air hyperventilation in 8 asthmatics. Exercise consisted of 6 min of steady-state exercise at 90% predicted maximal heart rate breathing compressed air at 0% humidity and 21 +/- 1 degrees C (mean +/- SD). During baseline exercise studies, FEV1 fell 41.6 +/- 15.8%, but only 12.8 +/- 8.5% during alpha-adrenergic blockade (p less than 0.001). Isocapnic cold air challenge consisted of breathing compressed cold air (0% humidity, -17 +/- 4 degrees C) for 3-min periods, with stepwise increases in minute ventilation (Ve) until the FEV1 fell at least 20%. During baseline cold air challenges, FEV1 fell 20% (PD20 FEV1) at a Ve of 48.8 +/- 21 L/min. However, during alpha-adrenergic blockade 6 asthmatics were able to achieve much higher levels of VE (86.6 +/- 22.7 L/min) before FEV1 fell 20% (p less than 0.01), and 2 asthmatics did not decrease their FEV1 by 20%, despite reaching maximal levels of ventilation of 132 and 108 L/min, respectively. Alpha-adrenergic blockade did not affect airways responses to histamine or ragweed antigen (p greater than 0.1).(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic alpha-Antagonists↗
PubMed1978

Heat wave mortality in nursing homes.

Patterns of mortality in 11 air-conditioned and 9 un-air-conditioned nursing homes in New York City have been investigated to determine the impacts of heat waves on nursing home occupants and the efficacy of air conditioning in reducing these impacts. During each of four heat waves in 1972 and 1973, the number of deaths in un-air-conditioned nursing homes was significantly greater than the number of deaths expected on the basis of mortality during cooler control periods. In contrast, deaths in air-conditioned nursing homes were not significantly different from expected. The age- and sex-adjusted ratio of relative death rates was 2.29 (95% confidence interval = 1.75-2.98). Approximately 94 excess deaths occurred in the un-air-conditioned nursing homes. On the basis of this research, it is recommended that nursing homes and other institutions for the elderly located in climates like that of New York City be required to provide air conditioning.

Aged↗
PubMed1980

Prediction of maximal oxygen intake over a wide range of air temperature conditions.

The correction of air temperature effect and the amendment of underestimation are two difficult problems for accomplishment of prediction of maximal oxygen intake from a simple submaximal test. The purpose of this study was to develop the prediction equation applicable over a wide range of air temperature conditions with no tendency of underestimation. Submaximal data were obtained from short exposure experiments to 20 degrees C, 30 degrees C and 40 degrees C of air temperature in a climatic chamber. The most valid prediction equation for young adult females was developed as VO2 max =[95.182VO2/(0.763Ve-1.092Wt-1.542Yr+16.82VO2+0.361OR+0.110Ht+63.655)]+0.126, and the one for young adult males was determined as V02 max =[87.919VO2/(0.484Ve-0.583Wt-1.354Yr+0.295OR+12.15VO2-0.110Ht+81.009)]+0.434 using the oxygen intake (VO2), pulmonary ventilation (Ve), ratio of oxygen removal (OR) during submaximal test work and body weight (Wt), stature (Ht) and age (Yr) of subjects.

Adolescent↗
PubMed2006

Occupational exposure to nitrous oxide - the role of scavenging and ventilation systems in reducing the exposure level in operating rooms.

OBJECTIVES: The aim of this study was to assess the level of occupational exposure to nitrous oxide (N(2)O) in operating rooms (ORs), as related to different ventilation and scavenging systems used to remove waste anaesthetic gases from the work environment. METHODS: The monitoring of N(2)O in the air covered 35 ORs in 10 hospitals equipped with different systems for ventilation and anaesthetic scavenging. The examined systems included: natural ventilation with supplementary fresh air provided by a pressure ventilation system (up to 6 air changes/h); pressure and exhaust ventilation systems equipped with ventilation units supplying fresh air to and discharging contaminated air outside the working area (more than 10 air changes/h); complete air-conditioning system with laminar air flow (more than 15 air changes/h). The measurements were carried out during surgical procedures (general anaesthesia induced intravenously and maintained with inhaled N(2)O and sevofluran delivered through cuffed endotracheal tubes) with connected or disconnected air scavenging. Air was collected from the breathing zone of operating personnel continuously through the whole time of anaesthesia to Tedlar((R)) bags, and N(2)O concentrations in air samples were analyzed by adsorption gas chromatography/mass spectrometry. RESULTS: N(2)O levels in excess of the occupational exposure limit (OEL) value of 180mg/m(3) were registered in all ORs equipped with ventilation systems alone. The OEL value was exceeded several times in rooms with natural ventilation plus supplementary pressure ventilations and twice or less in those with pressure/exhaust ventilation systems or air conditioning. N(2)O levels below or within the OEL value were observed in rooms where the system of air conditioning or pressure/exhaust ventilation was combined with scavenging systems. Systems combining natural/pressure ventilation with scavenging were inadequate to maintain N(2)O concentration below the OEL value. CONCLUSION: Air conditioning and an efficient pressure/exhaust ventilation (above 12 air exchanges/h) together with efficient active scavenging systems are sufficient to sustain N(2)O exposure in ORs at levels below or within the OEL value of 180mg/m(3).

Air Pollutants, Occupational↗
PubMed2003

Preliminary measurements of aromatic VOCs in public transportation modes in Guangzhou, China.

This study examined the exposure level of aromatic volatile organic compounds (VOCs) in public transportation modes in Guangzhou, China. A total of 40 VOC samples were conducted in four popular public commuting modes (subway, taxis, non-air-conditioned buses and air-conditioned buses) while traversing in urban areas of Guangzhou. Traffic-related VOCs (benzene, toluene, ethylbenzene, m/p-xylene and o-xylene) were collected on adsorbent tubes and analyzed by thermal desorption (TD) and gas chromatography/mass-selective detector (GC/MSD) technique. The results indicate that commuter exposure to VOCs is greatly influenced by the choice of public transport. For the benzene measured, the mean exposure level in taxis (33.6 microg/m(3)) was the highest and was followed by air-conditioned buses (13.5 microg/m(3)) and non-air-conditioned buses (11.3 microg/m(3)). The exposure level in the subway (7.6 microg/m(3)) is clearly lower than that in roadway transports. The inter-microenvironment variations of other target compounds were similar to that of benzene. The target VOCs were well correlated to each other in all the measured transports. The concentration profile of the measured transport was also investigated and was found to be similar to each other. Based on the experiment results, the average B/T/E/X found in this study was about (1.0/4.3/0.7/1.4). In this study, the VOC levels measured in evening peak hours were only slightly higher than those in afternoon non-peak hours. This is due to the insignificant change of traffic volume on the measured routes between these two set times. The out-dated vehicle emission controls and slow-moving traffic conditions may be the major reasons leading elevated in-vehicle exposure level in some public commuting journeys.

Air Pollutants↗
PubMed1982

A standard determination of paired air- and bone-conduction thresholds under different masking noise conditions.

Air-(ac) and bone-conduction (bc) thresholds were determined for 96 subjects in the age range 16-30 years. The bc tests were carried out using a B-71 vibrator applied to left and right mastoid under three conditions at the contralateral ear: unoccluded, masked at 25 dB and at 40 dB sensation level; ac audiometry and masking noise used a TDH-39 earphone. By a systematic process of otological classification of the subjects, the bc threshold for 'normal hearing' could be estimated with an uncertainty of less than 1 dB and interpolated for masking noise levels from zero to 40 dB sensation level. Results are expressed as alternating force levels in an artificial mastoid of current commercial design. Variance of the air-bone difference for individual ears is found to be less than the sum of ac and bc threshold variances calculated separately, implying strong air-bone correlation. Comparison is made with other recent studies using B-71 and KH-70-type vibrators, and average results are presented in the context of a proposed international standard for the normal threshold of hearing by bc.

Adolescent↗
PubMed1981

[Air environment conditions in the patients' rooms of multistory hospitals].

Air conditions, in winter and summer, were studied in 4 hospital rooms of the multistorey Institute of Obstetrics and Gynaecology, Medical Academy - Sofia. The studies were carried out in the following principal directions: I) Chemical pollution of air; 2) Microbic contamination; 3)Physical state of the environment; 4) Physiological examinations of 52 afebrile patients. The air in the hospital rooms depends on season, storey, cubage, heating regime, airing and maintaining, expressed by various indices. The state of the patients examined according to some principal physiological indices is adequate to the physical components of the environment.

Air↗
PubMed2002

Upper respiratory symptoms associated with aging of the ventilation system in artificially ventilated offices in São Paulo, Brazil.

BACKGROUND: The increase of work-related respiratory complaints in artificially ventilated buildings has multiple causes, and the role of allergen exposure and symptoms is still controversial. STUDY OBJECTIVES: To analyze the risk factors and the association of work-related symptoms with allergen exposure and different conditions of the same air conditioning system in São Paulo, Brazil. DESIGN: Workers were classified according to characteristics of the air conditioning system: the first group (group 1) with ventilation machinery and ducts with > 20 years of use, the second group (group 2) with ventilation machinery with > 20 years of use and ventilation ducts with < 2 years of use, and the third group (group 3) with ventilation machinery and ducts with < 2 years of use. Logistic regression was performed to check the associations between air conditioning groups, allergen exposure (fungi, mites, animal dander, and cockroach), and symptoms. RESULTS: There was a higher prevalence of building-related worsening of respiratory symptoms (p = 0.004; odds ratio [OR], 8.53) and symptoms of rhinoconjunctivitis (p = 0.01; OR, 8.49) in group 1. There was a lower relative humidity (p = 0.05) and nonsignificant lower temperature in group 1, when compared to the other groups. The viable mold spores totals were higher outdoors than in the indoor samples (n = 45, p = 0.017). There were higher levels of Der p 1 in group 2 (p = 0.032). All allergen levels were considered low. CONCLUSION: There was a strong association of building-related upper-airway symptoms with places having ventilation systems with > 20 years of use.

Age Factors↗
PubMedDate not supplied

Indoor spread of respiratory infection by recirculation of air.

Stimulated by an outbreak of measles that was spread throughout a school by the ventilating system, we looked into the possibility of preventing this hazard in air conditioned buildings. The amount of air recirculated by air conditioning systems increases as the temperature difference between indoor and outdoor air increases and often exceeds 70 per cent. Germicidal u.v. radiation in central supply ducts seems almost ideally suited for disinfecting recirculated air, being effective, safe, and cheap. The effectiveness of disinfecting recirculated air in blocking person to person transmission of airborne infection can be predicted to be great at the beginning of a potential outbreak and negligible during an established epidemic. Infection introduced by the air conditioning process, recently implicated in causing Legionnaires' Disease, might also be prevented. Air disinfection would supplement immunization in the control of respiratory infection and might be cost effective.

Air Conditioning↗
PubMed1999

Indoor air quality and the law in Singapore.

With the greater use of air-conditioned offices in Singapore, achieving good indoor air quality has become an important issue. The laws that impose duties upon designers and contractors with respect to the design and construction of air-conditioning and mechanical ventilation (ACMV) systems are set out in the Building Control Regulations and the Singapore Standard Code of Practice for Mechanical Ventilation and Air-conditioning in Buildings (hereinafter "SS CP 13:1980"). ACMV maintenance is governed by the Environmental Public Health Act, the Building and Common Property (Maintenance and Management) Act, and the Land Titles (Strata) Act, as well as by lease or tenancy agreements. Designers, contractors, developers, building owners and management corporations may also be liable to the workers, occupants and other premises users for indoor air quality (IAQ)-related injuries under the general principles of contract and tort. Recently, the Guidelines for Good Indoor Air Quality in Office Premises was issued by the Ministry of Environment to complement SS CP 13:1980 toward improving the indoor air quality of air-conditioned office premises. Although the Guidelines have no statutory effect, they may be adopted as contractual requirements in construction, lease and maintenance contracts. They may also be used to determine the relevant standard of duty of care required to discharge tortious liability. This paper looks at the existing laws and rules affecting the design, construction and maintenance of air-conditioned offices in light of Part III of the Ministry's Guidelines.

Air Conditioning↗
PubMed2004

Microbial air quality in mass transport buses and work-related illness among bus drivers of Bangkok Mass Transit Authority.

The air quality in mass transport buses, especially air-conditioned buses may affect bus drivers who work full time. Bus numbers 16, 63, 67 and 166 of the Seventh Bus Zone of Bangkok Mass Transit Authority were randomly selected to investigate for microbial air quality. Nine air-conditioned buses and 2-4 open-air buses for each number of the bus (36 air-conditioned buses and 12 open-air buses) were included. Five points of in-bus air samples in each studied bus were collected by using the Millipore A ir Tester Totally, 180 and 60 air samples collected from air-conditioned buses and open-air buses were cultured for bacterial and fungal counts. The bus drivers who drove the studied buses were interviewed towards histories of work-related illness while working. The results revealed that the mean +/- SD of bacterial counts in the studied open-air buses ranged from 358.50 +/- 146.66 CFU/m3 to 506 +/- 137.62 CFU/m3; bus number 16 had the highest level. As well as the mean +/- SD of fungal counts which ranged from 93.33 +/- 44.83 CFU/m3 to 302 +/- 294.65 CFU/m3; bus number 166 had the highest level. Whereas, the mean +/- SD of bacterial counts in the studied air-conditioned buses ranged from 115.24 +/- 136.01 CFU/m3 to 244.69 +/- 234.85 CFU/m3; bus numbers 16 and 67 had the highest level. As well as the mean +/- SD of fungal counts which rangedfrom 18.84 +/- 39.42 CFU/m3 to 96.13 +/- 234.76 CFU/m3; bus number 166 had the highest level. When 180 and 60 studied air samples were analyzed in detail, it was found that 33.33% of the air samples from open-air buses and 6.11% of air samples from air-conditioned buses had a high level of bacterial counts (> 500 CFU/m3) while 6.67% of air samples from open-air buses and 2.78% of air samples from air-conditioned buses had a high level of fungal counts (> 500 CFU/m3). Data from the history of work-related illnesses among the studied bus drivers showed that 91.67% of open-air bus drivers and 57.28% of air-conditioned bus drivers had symptoms of work-related illnesses, p = 0.0185.

Air Conditioning↗
PubMedDate not supplied

Evaluation of buoyant hydrofitness devices for leg musculoskeletal conditioning.

Air splints have been used for immobilization of fractures, skin graft stabilization and preprosthetic rehabilitation of the amputated lower limb. The purpose of this clinical study was to assess its use as a hydrofitness device to facilitate walking reeducation, to produce muscle strengthening and to increase joint extensibility in patients with weak legs. The performance of the air splint as a hydrofitness device was compared to that of the new foam hydrofitness device. The parameters used to assess the performance of these devices included durability, application and removal times, joint extensibility and the magnitude of the fluid drag forces. On the basis of this evaluation, the performance of the foam hydrofitness device was judged to be superior to that of the air splint for leg musculoskeletal conditioning.

Humans↗
PubMed2005

Respiratory health of bus drivers in Hong Kong.

OBJECTIVE: We conducted a cross-sectional study to evaluate the lung function and respiratory symptoms of Hong Kong bus and tram drivers exposed to air pollutants. METHODS: Demographic information, vital signs, pulmonary function, respiratory symptoms and blood lead levels in 358 male drivers of air-conditioned buses (ACB) were compared with 129 male drivers of non-air-conditioned buses and trams (NACB). Particulate matter (PM10), carbon dioxide (CO2) and carbon monoxide (CO) levels were measured in 16 air-conditioned and 15 non-air-conditioned trams along the same route. RESULTS: Forced vital capacity, forced expiratory volume in 1 s and maximal voluntary ventilation were lower but blood lead levels were higher in the NACB drivers compared with ACB drivers. More NACB drivers compared to ACB drivers reported frequent productive cough, dry cough, as well as sore throat. The measured lung function parameters in the NACB drivers were lower than a cohort of personnel working in an academic environment. The work-year duration was longer and scheduled days off per month were shorter for NACB (13.4+/-8.8 years and 4.3+/-1.3 days) compared to ACB drivers (11.5+/-9 years and 5.4+/-0.8 days), respectively (P < 0.001). The PM10 and CO2 levels were higher in ACB (265+/-83 microg/m3 and 2,114+/-69.6 ppm) compared to non-air-conditioned trams (161+/-103 microg/m3 and 500 ppm, respectively) (P < 0.005). CONCLUSION: We hypothesise that prolonged exposure to air pollutants adversely affects lung function in our NACB drivers but air recirculation could result in higher blood lead levels in ACB drivers.

Adult↗
PubMed1984

The sick building syndrome: prevalence studies.

Random samples or the entire workforce in nine offices in which similar clerical work was being performed were studied using a doctor administered questionnaire that inquired into symptoms that have been linked with the "sick building syndrome." Five of the offices were fully air conditioned, one had recirculation of air and mechanical ventilation, and three were naturally ventilated. Workers in three air conditioned and three naturally ventilated buildings were interviewed blind. Seven of the buildings were studied at our request in the absence of any known problem. Comparison of prevalences of symptoms between the naturally ventilated and the other buildings showed a repeated pattern of nasal, eye, and mucous membrane symptoms with lethargy, dry skin, and headaches. There were highly significant excesses of these six symptoms in the air conditioned buildings when compared by chi 2 tests with the naturally ventilated buildings. It is suggested that these six symptoms represent the sick building syndrome and that the size of the problem is probably greater than is currently recognised. Possible causes are discussed.

Air Conditioning↗
PubMed1983

[The effect of conditioning inhaled air in exercise-induced asthma].

The effect of conditioning of the inhaled air on exercise-induced bronchospasm was studied in adult asthmatic patients. In case of inhaling humified air of body temperature, the lung function parameters showed hardly any change after exercise compared to those detected before the test, i.e. the bronchoconstrictive effect of physical exertion could not or hardly be observed.

Air Conditioning↗