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M Israeli 《Health physics》1985,49(6):1069-1083
Deposition rates and velocities of indoor Rn progeny for both attached and unattached species are estimated from simultaneous measurements performed in 20 houses during 12 months. Fitting the values of working level ratio (the "equilibrium fraction"), the ratio between track densities of filtered and bare nuclear track detectors, section the air exchange rate, and the concentration of condensation nuclei to a theoretical model enabled us to calculate the average deposition rates for the houses in the study. This approach avoids the need to measure deposition rates on different types of surfaces in a house, and yields average values for houses with similar features (e.g. room sizes, heating, and air conditioning). Deposition rates were found to lie within about a factor of two of the average during the year, and exhibit higher values in the winter and lower values in the summer. Average deposition rates for the houses in the study were calculated to be 8 hr-1 and 1 hr-1 for unattached and attached radon daughters, respectively. These values correspond to deposition velocities of about 0.1 cm/sec and 0.015 cm/sec.  相似文献   

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The percentage of senior citizens in the Netherlands will rise in coming years. The expected percentage for the year 2010 of persons over age 65 in the total population is 15%. More persons over age 65 than ever before will continue to live in their own environment. Emergency response systems (ERS) can support independent living. The most common type of organization distributing ERS is a small, partly subsidized local alarm organization run by a social welfare office for the elderly. Government subsidy has been reduced in recent years which has motivated small organizations to join together into larger regional organizations in order to get a more solid financial base. On the other hand new semi-commercial and commercial organizations have come into being. These developments are part of the growing importance of home care, leading to more medical applications of ERS. User satisfaction with ERS is high. Portable triggers can enhance the effectiveness of the system. However, many users do not wear the portable trigger when feeling well. Future technical developments will result in multifunctionality of ERS-devices. In the long term the hardware of today will be integrated in a multimedia home terminal replacing the telephone. The portable trigger will remain the only specific hardware at home for ERS.  相似文献   

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Objectives: Previous studies have demonstrated that persons working with poultry have an increased incidence of chest symptoms and decreased lung function. A study was undertaken to evaluate the usefulness of airway responsiveness measurements to diagnose the presence of airways inflammation and relate this to the workplace exposure. Methods: The group studied comprised of 42 non-smoking poultry workers and 40 controls not exposed to organic dusts. The presence of symptoms was evaluated using a standardized questionnaire for organic dust exposures. Airway responsiveness was measured using the methacholine challenge test. The concentrations of airborne endotoxin and (1→3)-β-d-glucan were measured. Results and Conclusions: Exposure levels were in excess of those expected to cause effects in the airways. There was significantly higher airway responsiveness among the workers compared to controls (decrease 9.5 SD 7.5 vs 3.4, SD 3.3). Poultry workers had a higher prevalence of toxic pneumonitis, airways inflammation and chronic bronchitis compared to controls. Endotoxin levels in the poultry buildings exceeded those earlier suggested as the threshold value for airways inflammation.  相似文献   

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The hygiene of drinking utensils in licensed houses   总被引:1,自引:0,他引:1  
BUNKER HJ 《Public health》1948,61(5):85-88
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新建房屋白蚁预防处理保证期限的探讨   总被引:3,自引:1,他引:2  
白蚁是世界性的害虫之一,可危害堤坝、建筑、农林作物、交通、通讯设施及各种室内用品等,在我国分布和危害遍及25个省和自治区,长江以南地区尤为严重.据资料统计[1],仅房屋建筑方面,长江流域白蚁危害率一般可占房屋总数的40%~50%,华南地区可达60%~80%.  相似文献   

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The transport of 222Rn from soil, through a vented crawl space, and into the living space of single-family residences was studied. Two houses were monitored in detail for periods of 5 and 7 weeks. With crawl space vents open, the average indoor 222Rn concentrations were 1.2 and 0.6 pCi 1.-1 (44 and 22 Bq m-3); with the vents sealed the averages rose to 2.2 and 1.0 pCi 1.-1 (81 and 37 Bq m-3). The data suggest that, of the Rn released into the crawl space from the soil beneath the house, a significant fraction, perhaps 50% or more, enters the living space. The effect of 3 meteorological parameters--wind speed, indoor-outdoor temperature difference, and rate of barometric pressure change--on Rn concentration and entry rate were examined. In 1 of the houses a higher temperature difference corresponded to a higher indoor concentration, suggesting that the increased infiltration rate is more than compensated by an increase in the Rn entry rate. On the other hand, a high wind speed tended to reduce the indoor concentration, presumably by increasing both cross-ventilation of the crawl space and the infiltration rate of the living space. Results suggest that Rn transport into the crawl space of at least 1 of the houses occurred by pressure-driven flow, rather than solely by molecular diffusion. The diffusion coefficient of 222Rn through polyethylene sheeting, such as was present on the ground beneath this house, was measured in the laboratory and found to range from 0.65 X 10(-7) cm2 s-1 at 11 degrees C to 1.6 X 10(-7) cm2 s-1 at 25 degrees C, implying that the maximum diffusive flux through the sheet was many times smaller than that necessary to account for the rate of Rn entry into the house. A third house was studied using a tracer gas injected into the crawl space at a controlled rate. The fraction of air leaving the crawl space that entered the living space ranged from 0.3 to 0.65, in good agreement with results for Rn transmission in the other 2 houses, assuming that the 222Rn flux into the crawl space was comparable to that which would have resulted from molecular diffusion from soil having a 222Rn diffusion length of 1.0 m. By sealing leaks in the floor of this house, the average infiltration rate was reduced by 25%, but the indoor concentration of the tracer gas remained constant.  相似文献   

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