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Lab Safety: Overcrowded STEM/STEAM Labs and Makerspaces

By Ken Roy

Posted on 2022-03-31

In middle schools and high schools, formal laboratories are designed and used for hands-on activities in curricular areas such as science, technology and engineering (T&E) education, STEM/STEAM (science, technology, engineering, arts, and mathematics), and so on. Safety requirements for laboratories and makerspaces must include appropriate facility design considerations, engineering controls, standard operating procedures, and personal protective equipment (PPE). These safety requirements address potential safety hazards and resulting health/safety risks in formal labs and makerspaces that are normally not associated with other subject-area classrooms (math, language arts, world languages, and so on). 

Under the duty or standard of care legal component, lab/makerspace instructors and supervisors/administrators are charged with ensuring a safer teaching and learning environment in labs/makerspaces by following appropriate hazard analyses and resulting risk assessments and implementing appropriate safety actions (for more details, see the NSTA Safety Blog post A Three-Step Method for Safer Labs). A major component of this legal piece is “duty of supervision.” (See NSTA’s Legal Implications of Duty of Care for Science Instruction white paper.)

Working Toward Safer Labs and Makerspaces: Occupancy Load

According to the National Fire Protection Association (NFPA), one means of addressing life safety involves calculating occupant loads in school buildings and their instructional spaces encompassing classrooms and laboratories (NFPA 101 Life Safety). Occupant load by definition is the total number of persons that might occupy a building or portion thereof (like a lab, makerspace, or classroom) at any one time. If a facility is occupied by too many people, the risk of injury and illness emergency increases dramatically.

A 2020 national research study—Safer Engineering and CTE Instruction: A National STEM Education Imperative, by Drs. Tyler Love and Kenneth Roy (Love and Roy 2022)—revealed serious safety issues related to P–12 Technology/Engineering and STEM facilities and instructional practices. When analyzing the enrollments of teachers’ largest classes, no region in the United States had enough facilities to host the number of classes with 24 or more students according to the NFPA 101 square-footage calculation. From a national perspective, 57% of study participants indicated their largest class had 25 or more students enrolled. However, only 26% of participants indicated they had a facility large enough (greater than 1,250 square feet) to host 25 or more students. This mismatch among enrollment and facility net square footage creates a potential legal and safety issue in the event of an emergency. This is extremely concerning, given that results from previous research studies found a significant increase in school lab accidents as 1) square footage dropped below 60 square feet per occupant, and 2) enrollments in lab-based courses increased to 24 students or more per one instructor (Stephenson et al. 2003; West and Kennedy 2014). 

Although a facility may have enough square footage to allow for hosting more than 24 students and 1 teacher as occupants, according to the NFPA 101 Life Safety Code requirements, research findings, and better professional safety practices clearly advise against this. They demonstrate that when a single instructor is tasked with supervising more than 24 students involved in lab/makerspace activities, there is a significantly greater chance of an accident occurring. Based on the research findings, Love and Roy (2022) strongly recommended that school districts, administrators, district safety officers, school counselors, STEM educators, and CTE (career and technical education) teachers collaborate to closely reexamine their class occupancy load guidelines. These individuals should work together to ensure no more than 24 students per instructor are enrolled in STEM, makerspace, or CTE lab-based classes, which can pose greater potential hazards and resulting risks than other courses.

Working Toward Safer Labs and Makerspaces: Class Size

As Love and Roy (2022) highlight in their free downloadable book, further overlap among the safety policies and practices in science education, T&E education, and CTE areas are noticeable from the application of seminal research on lab occupancy loads. Stephenson et al. (2003) found that the rate of accidents in P–12 science labs significantly increased when enrollment exceeded 24 students, when square footage dropped below 60 square feet per student, and when room/lab size was less than 800 square feet.

As previously mentioned, Love and Roy’s (2022) study found that 57% of respondents across the United States reported their largest class enrollments exceeded 24 students. Based on legal safety standards and better professional safety practices, this could be considered a legal safety issue relative to the teachers’ duty of care for direct supervision. This could also potentially exceed the occupancy load requirements mandated by the NFPA 101 Life Safety Code. When coupled with 40% of the respondents indicating that they had insufficient student workspace, this raises serious safety concerns. Better professional safety practices informed by research findings (Love and Roy 2022; Stephenson et al. 2003; West and Kennedy 2014) suggest that no more than 24 persons occupy a STEM lab or makerspace to reduce the chance of an accident. However, it must be noted that the “24 students and 1 teacher as occupants” recommendation only applies if there is at least 50 net square feet available per occupant (1,250 total net square feet), according to the NFPA 101 Life Safety Code 101: 2021 edition, p. 101–183, Table Occupant Load Factor.

In the NSTA Safety Advisory Board’s white paper, Overcrowding in the Instructional Space, factors affecting safety in laboratories in addition to occupancy load may include facilities design, engineering controls, appropriate PPE, standard operating procedures, and/or safety training of students and teachers.

Overcrowding in science classrooms is the number one concern among science teachers (Stephenson et al. 2003; West et al. 2001; West and Kennedy 2013). However, overcrowding—as well as lack of safety training of teachers; lack of appropriate classroom management; and inadequate science equipment and facilities—have all been identified as possible areas of safety concern while teaching science (Stephenson et al. 2003; West and Kennedy 2014). Standards of care for student safety are incorporated in building codes and guidelines established by voluntary association and by law and regulation (National Research Council 2006). The size of the area where lab and makerspace activities are occurring in conjunction with the number of students occupying the area are considered when determining standards of care. 

Research has documented that more accidents occur in STEM/STEAM courses that have enrollments exceeding 24 students (Stephenson et al. 2003; West and Kennedy 2014). Major problems associated with overcrowding include two main issues: the teacher’s ability to supervise a large number of students doing STEM/STEAM activities and the amount of individual workspace per student to conduct those activities in a safer manner. Overcrowding with regard to supervision will likely affect a teacher’s ability to properly manage and oversee their classroom, thereby preventing adequate supervision of students conducting potentially hazardous activities.

Additionally, in her International Technology and Engineering Educators Association (ITEEA) article, West (2016) noted that for more than 30 years, studies have found overcrowding to be the top safety concern among STEM teachers. Similarly, Roy and Love’s (2022) study found overcrowding to be the second greatest perceived cause of accidents in STEM labs, second to students’ failure to follow safety protocols. Moreover, West (2016) described the strong positive correlation found between overcrowding and increased accident rates in P–12 STEM labs. Class sizes greater than 24 (in any one class) limit a teacher’s ability to supervise a large number of students doing STEM activities with hazardous chemicals, materials, tools, or equipment. Overcrowding limits an instructor’s ability to adequately supervise all students during lab activities and ensure every student is properly following all safety protocols. 

Safer Occupancy Loads and Pupil-Teacher Ratios Should Not Be Ignored

First, occupancy load levels need to be determined and addressed when scheduling students into lab courses, based on legal NFPA 101 Life Safety standards. This information usually is available either on original architectural building prints or by contacting the local fire marshal, who can calculate the lab occupancy load. The load factor is not only determined by next square footage, but also factors such as number of exits, types of potential hazard/risks, and so on. 

Secondly, there are additional reasons for occupancy load requirements involving supervision issues under duty or standard of care. Factors such as potential hazards and resulting risks due to physical, chemical, and biological hazards, and so on must considered when scheduling classes, especially secondary level CTE, T&E education, family and consumer sciences, natural sciences, and STEM/STEAM lab-based courses.

For example, STEM/STEAM labs and makerspace instructors potentially face more challenges related to student safety under duty or standard of care. This is because of the broad spectrum of physical (e.g., hand tools, power tools, 3-D printers, soldering irons, and so on), chemical (e.g., paints, chemical cleaners, lubricants, adhesives, and so on) and biological (e.g., plants, fungi, and so on) hazards and resulting risks that could be found in these teaching/learning spaces. Assume for the moment that the instructional STEM/STEAM lab or makerspace occupancy load level based upon the NFPA 101 Life Safety Code legal standard is calculated to accommodate up to 50 occupants. Other important criteria under duty or standard of care for the instructor must also be acknowledged and implemented. Therefore, limiting the class size to a maximum of 24 students for one instructor, or assigning two instructors with the proper safety training to supervise no more than 48 students would be a more legally sound and a safer plan of action based on the NFPA 101 Life Safety Code, research findings, and better professional safety practices suggested by NSTA and ITEEA. Even in the aforementioned maximum ratio example, a case could be made for the class being overcrowded. Again, a potential hazard analysis and resulting health/safety risk assessment needs to be conducted to determine if the ratio is in fact safer! (See OSHA Job Hazard Analysis). This would be based on better professional safety standards and possibly some legal standards or precedents. 

Educators, administrators, school counselors, state education department officials, and others should be aware that better professional safety practices are not voluntary or optional. Similar to legal safety standards, better professional safety practices are also viewed as a requirement according to the U.S. legal system.

Action Items: How to Address Safety Concerns Regarding Occupancy Load/Overcrowded Labs

The following actions are recommended to assist laboratory educators who are encountering issues with exceeded occupancy load and/or overcrowded laboratories:

  1. If you have more than 24 students in a laboratory course and are the only instructor, or if you have more occupants than the net square footage allows (50 square feet per occupant minus any tables, equipment, or other objects that occupy floor space), you need to consider in earnest temporarily stopping any hands-on laboratory activities or demonstrations. This is critical if you know or suspect after doing a hazard analysis and potential risk assessment that these activities are potentially unsafe and do not meet legal safety standards and better professional safety practices. You are potentially not only putting yourself and your students at risk, but you also are potentially placing yourself and your administration in legal jeopardy should a safety incident occur.
  2. Next, contact in writing your school system’s appropriate supervisor/administrator and/or other individual(s) responsible for safety (e.g. chemical hygiene officer or facilities safety officer, building administrator, curriculum director, school counselor(s), and others). Explain your concerns about occupancy load and/or overcrowded labs relative to safely implementing the required curricular activities. Provide resources about occupancy load (e.g., this NSTA Safety Blog post, Occupant Load Factor Table from NFPA 101, NSTA’s Overcrowding in the Instructional Space white paper, the 2016 article by West, and the free 2022 research book by Love and Roy).
  3. If this approach is not effective in rectifying the health and safety lab issues, contact your faculty union representative and get this group involved. Schedule an additional meeting to discuss your concerns and the criteria for occupancy load described in the aforementioned resources (step 2).
  4. If the issue is still not addressed and resolved in Step 3, in writing, request that your school system have the local fire marshal come in and re-evaluate the room’s occupancy load and general fire safety regulations for laboratories. You also might ask for an updated certificate of occupancy.
  5. Repeat the previously mentioned steps as occupancy loads, course activities, and facility space change. Above all, again, if you believe it is unsafe because of the noted safety factors, do not carry out any laboratory activities. If you believe you are being harassed as a result of these inquiries and told to carry out these activities as required by the formal curriculum, consider securing legal counsel and share your concerns. Remember that the laboratory teacher is the one who is the lab safety specialist and has the major legal responsibility under duty or standard of care to make sure the lab is safer for teaching/learning activities.


Love, T. S., and K. R. Roy. 2022. Safer engineering and CTE instruction: A national STEM education imperative. What the research tells us. International Technology and Engineering Educators Association. 

Stephenson, A. L., S. S. West, J. F. Westerlund, and N. C. Nelson. 2003. An analysis of incident/accident reports from the Texas secondary school science safety survey 2001. School Science and Mathematics 103 (6): 293–303.

West, S. S. 2016. Overcrowding in K–12 STEM classrooms and labs. Technology and Engineering Teacher 76 (4): 38–39.

West, S., and L. Kennedy. 2014. Science safety in secondary Texas schools: A longitudinal study. Proceedings of the 2014 Hawaiian International Conference on Education. Honolulu, HI. 

Safety Blog Acknowledgement

NSTA Chief Safety Blogger Dr. Ken Roy wishes to sincerely thank nationally and internationally recognized T&E education safety specialist Dr. Tyler Love, Assistant Professor of Elementary/Middle Grades STEM Education and Director, Capital Area Institute for Math and Science at Penn State University, Harrisburg, for his professional review of and contributions to this commentary.

Submit questions regarding safety to Ken Roy at Follow Ken Roy on Twitter: @drroysafersci.

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