Two perpendicular 10-point traverses were taken repeatedly over several months on a total of 35 branch ducts on 4 working industrial exhaust ventilation systems using a calibrated digital manometer connected to a laptop computer. An attempt to improve the method by using the geometric mean of two measurements of the centerline value instead of a single value made no discernible difference. When a person passes through an NPIR doorway, there exists an exchange of air between the isolation room and the area beyond its door. A small cart carried a mannequin through a doorway, separating a laboratory NPIR and an SF6 measurement chamber. While this study concerned itself primarily with the engineering control of the transmission of airborne infectious diseases provided by ventilation systems, the results are applicable to any environment where a clean area is separated from a less-clean area by a doorway.
More printing is done using the lithographic process than any other.
High volatility and solubility for ink are valuable solvent characteristics, so that printing is interrupted minimally. Recent EPA regulations have resulted in the development of cleaning solvents having lower volatility, thus reducing worker exposures in some cases. However, small printers typically have no provision for an adequate supply of conditioned fresh air necessary to dilute the airborne solvent vapors to safe concentrations while maintaining temperature and humidity in a range suitable for comfort and good printing. In one case, the fresh air was introduced to the press room at one end and stale air exhausted from the other end. In a second case, the fresh air was fed to the return air side of the press room HVAC system and the exhaust was taken from points several feet above the operating presses.