Laser Hazards in the Laboratory

Ultraviolet, visible, and near-infrared radiation from lamps and lasers in the laboratory can produce a number of hazards. Medium-pressure Hanovia 450 Hg lamps are commonly used for ultraviolet irradiation in photochemical experiments. Powerful arc lamps can cause eye damage and blindness within seconds. Some compounds, for example, chlorine dioxide, are explosively photosensitive. 

Control measures for the safe use of lasers have been established by the American National Standards Institute (ANSI) and presented in Safe Use of Lasers (ANSI Z136.1-1993), which describes the different types of laser hazards and the appropriate measures to control each type. Class lEB and IV lasers should be operated only in posted laser-conholled areas. No one but the authorized operator of a laser system should ever enter a posted laser-controlled laboratory when the laser is in use. 

Lasers are commonly used in the laboratory, although in many instruments, most lasers are embedded in instrumentation and are therefore shielded or protected by optical barriers and interlocks that, when functioning properly, prevent accidental exposure. Care must be exercised when performing maintenance or when changing samples in such instruments. In this section we provide basic information on laser safety and hazards (Refs. 1 to 3). This is by no means exhaustive nor is it meant to substitute for an understanding of the specific safety requirements of instrumentation, or applicable law or regulations. The special case of common laser pointers has received considerable attention recently and is treated separately. We note that as of 2007, the general practice in the United States is to use the lEC definitions. 

Since the first edition of the book, the expansion of Raman spectroscopy as an analytical tool has continued. Thanks to advances in laser sources, detectors, and fiber optics, along with the capability to do imaging Raman spectroscopy, the continued versatility of FT-Raman, and dispersive based CCD Raman spectrometers, progress in Raman spectroscopy has flourished. The technique has moved out of the laboratory and into the workplace. In situ and remote measurements of chemical processes in the plant are becoming routine, even in hazardous environments. 

There are at least four different kinds of equipment used in biomedical laboratories that can produce hazardous amounts of electromagnetic radiation. These are ultraviolet lamps, lasers, microwave ovens, and x- and gamma ray-producing equipment. Although ultrasonic baths do not produce electromagnetic radiation, the injury caused by this equipment is similar to that caused by microwaves thus we will discuss its use in this section. The hazards that these pieces of equipment pose and the preventive measures workers must observe are discussed in the following pages. 

Danger from the laser beam. Direct viewing of the laser beam must be avoided. This includes sighting down the beam since objects in the beam s path may be efficient reflectors. All lasers can produce eye damage— at any power level. Be especially aware of the hazard from specular reflections from objects in the beam s path, such as mirrors, walls, door knobs, laboratory furniture. Mis-aimed beams can produce a fire or explosion if the beam contacts flammable material. The laboratory should be checked for such hazards before operating the laser. 

Instruction. All individuals in a laboratory where lasers are operated must be informed of the potential hazard of accidental exposure to the laser beam. Safety rules should be prominently posted, and laboratory occupants should be advised of proper operating procedures. 

Because goggles offer little protection to the face and neck, full-face shields should be worn when conducting particularly hazardous laboratory operations. In addition, glassblowing and the use of laser or ultraviolet light sources require special glasses or goggles. 

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