By Ken Roy
Posted on 2022-03-01
Picture this scenario: In a STEM lab, three middle school students were standing together in a designated compound miter saw work safety zone. While the students were talking, but paying little attention to the miter saw, one of them decided to start the saw to cut a piece of wood. Unfortunately, the saw did a kickback action. A miter saw kickback occurs when the blade can’t cut the piece, and instead, it recoils the piece. It can be extremely dangerous, as the blade turns at a much faster speed. Because the crowded work area in front of the machine had little room to move, the machine operator could not escape fast enough, and the blade quickly cut two fingers off the operator’s hand.
This is one of several critical reasons STEM lab hazardous areas nearby machinery or equipment need to have safety zones, and the rule enforced about having only one machine/equipment operator in the space. Similar examples of work zone violations resulting in accidents have occurred during science labs, technology education/engineering labs, and other STEM lab–related activities. Safety zones are a critical aspect of all STEM education facilities.
You often see these yellow-and-black-striped “safety zones” either painted or taped on the STEM lab, technology education lab, and agriscience lab floors around power tool machinery. These zones are meant to be designed as three-dimensional spaces where only the operator and/or the instructor are to enter when the machine or other hazardous equipment is in use. Given that STEM labs usually have multiple power tools and other hazardous equipment, the safety zones should not interfere with an adjacent machine’s or hazardous equipment’s safety zone. It has also been recommended that there be a 28-inch walkway space between these machines/equipment when they are in operation.
However, remember that under Americans with Disabilities Act of 1990 (ADA) requirements/accommodations, walkway surfaces must be at least 36 inches wide and without abrupt level changes (no level change greater than ½ inch), and the surface must be stable, firm, and slip-resistant. Therefore, if you have a student with disabilities, make sure the ADA requirements are met in the appropriate lab locations. The purpose of the safety zone designations in yellow or yellow and black is to remind operators of potential slip/trip/fall hazards and resulting health and safety risks.
Additional potential safety issues associated with power tool machinery and/or other hazardous equipment areas, like a science workbench, that need to be taken into consideration might include noise levels, waste accumulation (e.g., wood and/or metal shavings, and/or dust, chemical splash, and/or spills), formation of projectiles, saw blade kickback, and interference from other individuals standing too close to machine operators.
In addition, if power tool machinery is placed in a back-to-back position, there should be a physical barrier of some type so the student machine operators can’t reach across to the other machine’s safety zone (or catch hands and materials in moving machine parts). The same criteria may need to be applied to hazardous science workbenches in the STEM lab, which allow by design, pairs of student workers to face each other on opposite sides. This is especially critical when dealing with hazardous chemicals or biologicals.
Unfortunately, science laboratories generally do not make use of safety zones floor signage, given that they basically use bench lab furniture to carry out experimentation. However, it is critical that the bench lab furniture allows for an appropriate safer distance for experimenters facing each other on opposite sides. Some science lab benches can accommodate four students (two on each side) and have shelving barriers in the middle to help protect student workers facing each other on opposite sides from splashes and spills. Other science and STEM laboratories have smaller bench lab furniture that only allows two students to work on the same side next to each other.
Certainly, in all cases, personal protective equipment (PPE)—like safety glasses with side shields or indirectly vented chemical splash goggles as appropriate—also help to limit injury should an accident happen. It is critical for teachers to train and continuously remind/supervise students, whether in a science laboratory or STEM laboratory, to work only within a safer distance from chemical and biological hazards and lab equipment/materials during activities, whether or not there are safety zones formally marked on the floor.
The Occupational Safety and Health Administration (OSHA) addresses floor marking guidelines in detail under its Walking-Working Surfaces standard #1910.22. Floor markings help employers determine how and where there is a need to use them and make the worksite safer. These standards go well beyond machine safety zones on STEM lab walkway floors, including aisles, passageways, and so on. However, be aware that the OSHA Code of Federal Regulations (CFR) 1910.22, Walking-Working Surfaces, reads simply, “Permanent aisles and passageways shall be appropriately marked.” Check out the website OSHA Floor Marking Standards for additional information.
As noted, OSHA technically has no specific standards on identifying or marking safety zones, other than using floor markings to help make the worksite safer. However, better professional safety practice can be used as a guide to help STEM lab designers/operators set up appropriate safety zones for the machinery/equipment. One example is as follows:
Metal and Woodworking Machines
A. Tool Grinders. The optimum size safety zone for a grinder would be 60 inches wide and 28 inches deep. A non-skid safety zone area should be placed about 6 inches back from the area directly in front of the machine. A suggested location for the grinder would be next to a wall, at the end of a workbench, at the end of the welding booths, or back-to-back with a machine of similar type.
Check out https://www.slosipe.org/media/documents/Safety_Zones_Around_Machinery.pdf for additional recommendations about work zones for specific STEM lab machinery.
Additional schematics of recommended safety zones around machinery can be found at
Assess the potential hazards and resulting risks of all machinery/equipment and recommended safety zones in the STEM laboratory. A roll of black-and-yellow tape or painted lines to designate safety zones on the floor (and non-skid strips near equipment that creates a lot of waste) are a minimal cost for something that can make students and their instructors aware of safety zones and potentially help limit expensive and serious accidents. Make sure the potential hazards and resulting risks are at an acceptable level as part of the decision for using such equipment in the lab. Equally important is the safety training and ongoing reminders/supervision for machine/equipment operators, including use of the safety zone only by one machine/equipment operator and the instructor.
Safety Blog Acknowledgement. NSTA Chief Safety Blogger Ken Roy wishes to sincerely thank nationally/internationally recognized technology education and engineering safety specialist Tyler Love, assistant professor of Elementary/Middle Grades STEM Education and director, Capital Area Institute for Math and Science (CAIMS) at Penn State University, Harrisburg, for his professional review of and contributions to this commentary.
Submit questions regarding safety to Ken Roy at firstname.lastname@example.org. Follow Ken Roy on Twitter: @drroysafersci.
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