Apparatus Seatbelt Study: Just How Big Is a Firefighter?

How big is a firefighter? While that sounds like a fairly simple and straightforward question, the answer turns out to be complicated and leads to many more questions. The American fire service is now being examined, measured and documented in a manner...


How big is a firefighter? While that sounds like a fairly simple and straightforward question, the answer turns out to be complicated and leads to many more questions. The American fire service is now being examined, measured and documented in a manner that goes far beyond all previous attempts...


To access the remainder of this piece of premium content, you must be registered with Firehouse. Already have an account? Login

Register in seconds by connecting with your preferred Social Network.

OR

Complete the registration form.

Required
Required
Required
Required
Required
Required
Required
Required
Required
Required

How big is a firefighter? While that sounds like a fairly simple and straightforward question, the answer turns out to be complicated and leads to many more questions. The American fire service is now being examined, measured and documented in a manner that goes far beyond all previous attempts.

The scientific field of anthropometrics (literally "human measurement") is concerned with the physical sizes and shapes of humans. The development of an anthropometric database for firefighters will provide much more information than has ever been available to ensure that our tools, equipment and clothing are designed to fit the users and accommodate our wide range of sizes and shapes.

Protective clothing manufacturers have gradually developed an expanded range of size options based on the need to fit an increasing variety of firefighter bodies, although many individuals, particularly females and smaller males, still complain about the inadequate range of standard sizes. Clothing has evolved primarily through trial and error or "made to measure" processes.

Until recently, most of the size and shape factors that were used by fire apparatus and equipment designers were based on some very basic and outdated assumptions about the weights and dimensions of firefighters. Much more comprehensive data is now available and even more will be produced in the next few years. All of this came from a determined attempt to study an important safety issue and the initial results have immediate implications for the design of fire apparatus.

The Seatbelt Problem

In the spring of 2005, an informal task force was assembled to focus on the basic problem of ensuring that the seats and seatbelts in fire apparatus would accommodate the range of firefighters who are expected to use them. The ongoing effort to ensure that every firefighter will be properly seated and secured in an approved riding position brought attention to a problem that had been ignored or glossed-over for at least a decade — firefighters were complaining that they simply could not fit into the seating areas and fasten the seatbelts in their fire apparatus. This news came as a surprise to many individuals who assumed that the dimensional requirements specified in National Fire Protection Association (NFPA) 1901, Standard for Motor Fire Apparatus, ensured that vehicles could accommodate almost any firefighter.

The first meeting was organized as a joint effort of the National Fallen Firefighters Foundation (NFFF) and the Safety Health and Survival Section of the International Association of Fire Chiefs (IAFC), and brought together members of the Safety Task Force of the NFPA 1901 Committee, apparatus manufacturers, seat manufacturers, seatbelt manufacturers and several interested fire service members, along with some experts in the study of anthropometrics. One fact revealed at the first meeting is that the standard dimensions incorporated in NFPA 1901 came from sources and assumptions that had been developed decades ago and for very different purposes.

Those standard measurements for seats were based on providing sufficient space for the 95th-percentile firefighter; incorporating the assumption that the space might not be sufficient for one firefighter in 20. The 5% factor was a commonly accepted design standard, based on the expectation that some people are just "too big" or "too small." Before the study of anthropometrics became sophisticated, most designers would aim to accommodate a range of individuals from the fifth-percentile female at the small end to the 95th-percentile male at the large end, anticipating that about 10% of the overall population would be outside the standard size range.

Experts in the field of anthropometrics have determined that the concept of a 95th percentile individual is highly theoretical. Humans come in a tremendous range of shapes and sizes with an infinite potential for variations in the relative dimensions of their body parts. A study conducted by an office chair manufacturer concluded that an adjustable chair designed to accommodate a range from the fifth-percentile female to a 95th-percentile male would really meet the needs of less than 68% of the overall population.

This content continues onto the next page...