BACKGROUND Dental technician's pneumoconiosis is a dust-induced fibrotic lung disease of fairly recent origin. This study was carried out to estimate its occurrence in Sweden. METHODS Thirty seven dental technicians in central and south eastern Sweden with at least five years of exposure to dust from cobalt chromium molybdenum (CoCrMo) alloys, identified by postal survey, agreed to undergo ch...

For responding the policy call of building a green and low-carbon society meeting goal economizing energy reducing emission in process construct. The troditional ceiling-exhaust ventilation system restroom should be replaced by new low-level wall-exhaust for better exhaust effect less air changes per hour which help solving existing problems, such as excessive design value hour, serious heating...

Table 1. Standard air density as a function of elevation above sea level (at 70F and 50% relative humidity). M echanical ventilation can be divided into three types: negative-, positive-, and neutral-pressure ventilation. Negativepressure systems use fans to exhaust air, thereby creating a slight partial vacuum that draws fresh air in from outdoors. Negative-pressure ventilation systems are use...

Recently, open-type push-pull ventilation systems have been widely employed as effective substitutes for the conventional local exhaust ventilation system, and have prevailed at many welding workshops in Japan. In this study, the effect of the uniform velocity on carbon dioxide (CO2) shielding arc welding was examined by laboratory experiments. The ventilation system examined in the experiments...

OBJECTIVES CO poisoning has been a serious industrial hazard in Japanese workplaces. Although incomplete combustion is the major cause of CO generation, there is a risk of CO poisoning during some welding operations. The aim of the present study was to evaluate the generation rate of CO from CO2 arc welding under controlled laboratory conditions and estimate the ventilation requirements for the...

Most ventilation and air conditioning systems are designed without much concern about how settling particles behave in ventilation air flows. For displacement ventilation systems, designers normally assume that all pollutants follow the buoyant air flow into an upper zone, where they are evacuated. This is, however, not always true. Previous studies show that high concentrations of settling res...

conclusions pressure support ventilation, but not spontaneous breathing, induces a significant redistribution of ventilation towards the ventral region. the sensitivity of the support trigger appears to influence the distribution of ventilation only during the early phase of inspiration. background in supine position, pressure support ventilation causes a redistribution of ventilation towards t...

A push-pull ventilation system is effective for hazardous material exhaustion. Although a push-pull ventilation system has advantages over a local exhaust hood, some laborious adjustments are required. The pertinence of the adjustments is uncertain because it is difficult to evaluate the performance of a push-pull ventilation system quantitatively. In this study, a measurement of the capture ef...

Health care workers (HCW) are exposed to ribavirin aerosol during therapy of infants with respiratory syncytial virus infections. To assess the degree of HCW exposure, we analyzed air samples from patient rooms and HCW personal breathing zones during ribavirin aerosol delivery by ventilator (two samples), oxygen hood (two samples), and a new vacuum exhaust hood (four samples). HCW exposure to r...

The present paper deals with the numerical study of horizontal laminar flow ventilation system for surgical site in hospital. When the orientation of supplies openings and exhausts are altered, the performance of ventilation system in terms of effectiveness of removal of contaminated particles is also affected. In this investigation, the performance of new horizontal Single Sided Supply and Exh...