A preliminary study was conducted to determine the effectiveness of a smoke evacuation system used in laser surgery. A 30 W medical CO2 continuous wave (CW) laser was used to make cuts in a pork chop to simulate smoke production during laser surgery. A commercially available smoke evacuation system was used to control the smoke from the simulated surgery. The smoke concentration was measured at 6 in and at 3 and 4 ft from site of laser interaction. The nozzle of the smoke evacuator was located at distances of 2, 6, and 12 in from the surgical site to measure the relative effectiveness of the control. Complete control of smoke was achieved when the nozzle was located at 2 in, but significant amounts of smoke escaped when the nozzle was located at 6 and 12 in. Suggestions for the use of the smoke evacuation system and areas for further study are given.

Environmental monitoring was conducted at an industrial facility to qualitatively identify the major contaminants generated while cutting fabrics and polymers with a 25 W CO2 continuous beam laser. Carbon monoxide, hydrogen cyanide, and particulates were also assessed, and a bulk sample of residue from the laser exhaust duct was analyzed for inorganic acids, pH, and volatile organic compounds. Samples were collected while cutting vinyl, acrylics, woven fabrics, felt, Formica(4', and Plexiglase) . The laser parameters were standardized to allow for meaningful comparison of results for each target material. The volatile organic compound samples were collected in multibed sorbent tubes with subsequent analysis via thermal desorption and gas chromatography/mass spectroscopy. Depending on the material being cut, a wide variety of compounds were detected. The highest relative concentrations of volatile compounds were found during laser cutting of felt fabrics. The lowest concentrations and fewest number of compounds were from woven fabrics. The compounds detected included hydrochloric acid, aldehydes, benzene, vinyl chloride, various acrylates, acrylonitrile, acetonitrile, styrene, furans, phenol, and butyl cellosolve. Methyl methacrylate was a significant peak detected during the laser cutting of acrylic ester polymers, Plexiglass, and polyvinyl chloride with adhesive backing. Carbon monoxide was not detected above background (2 ppm) during any of the laser cutting trials. Hydrogen cyanide was detected during the laser cutting of felt (15 ppm) and Formica® (8-10 ppm). Particles 0.3 pm in diameter (p Ind) generated during the laser cutting exceeded background particle levels by a factor of ten or more. Most compounds detected in the thermal desorption air samples were also detected in the bulk sample, and the residue was acidic (pH = 3). Area samples collected outside the laser enclosure suggested the local exhaust ventilation system sufficiently contained the air contaminants.

This method is simple, requires no specialized training, and permits regular monitoring of the necessary UV fluence rates needed to sustain the targeted airborne microorganisms' inactivation level. Additionally, this method allowed for the detection of changes in UV fluence rates in the upper air of the simulated hospital room.

The purposes and functions of semitransparent eye protective curtains are analyzed. Based upon this analysis, functional requirements are developed, and design requirements are specified for optimum curtains to be used with open arc welding and arc cutting processes. Such curtains also protect against other high intensity broad-spectral-band sources such as compact arc lamps. The requirements for filtering our hazardous UV radiation and blue light must be balanced against the need for transparency in the visible spectrum and the need for reduced glare. Infrared attenuation is shown to be of very little importance.

Data are presented on ankle-specific SARs and foot currents as a function of strengths of radio-frequency electromagnetic fields encountered by operators of dielectric heaters. The determination of foot currents was based on near-field exposures in which reactive coupling dominates, and which can result in substantial SARs in exposed workers. The operators were located less than one wavelength from--usually within one meter of--the dielectric heaters, which generated fields at frequencies from 6.5 to 65 MHz. At distances normally assumed by workers, maximal strengths of electric fields ranged from 10(4) to 2.4 x 10(6) V2/m2; maximal strengths of magnetic fields ranged from 5.0 x 10(-3) to 33.3 A2/m2. Currents through both feet to ground were measured while operators stood where they normally worked. Maximal currents ranged from 3 to 617 mA, rms. Nearly 27 percent of the dielectric heaters induced foot currents that exceeded the 200-mA limit that has been proposed for a new ANSI C95.1 standard. Twenty percent of the heaters induced foot currents that exceeded 350 mA. SARs in ankles were calculated from foot currents, and they approximated 5 W/kg at 100 mA, 29 W/kg at 250 mA, and 57 W/kg at 350 mA. The maximal SAR in the ankle was approximately 176 W/kg at 617 mA.