One Size Does Not Fit All

Posted on by Hongwei Hsiao, PhD


When your safety and your life depends on it, you need your equipment to fit properly. This is especially true in the workplace. Improper fit may prevent workers from performing their job duties safely and effectively. If your respirator does not seal properly to your face, if your gloves are too big, if your seatbelt cannot buckle with your safety gear on . . . you get the picture.

Anthropometry is the science of defining human body dimensions and physical characteristics. The National Institute for Occupational Safety and Health (NIOSH) conducts anthropometric research to prevent work-related injuries and deaths by studying how work spaces and equipment fit today’s diverse worker population. This includes the fit of machines, vehicles, and personal protective equipment (PPE). Much of the available data were collected in the 1950s and 1970s from military personnel and the general population from that era. These decades-old data do not represent, on average and collectively, the sizes and body types of today’s workers, who are much more diverse in age, gender, and ethnicity. NIOSH research has shown workers have unique shapes and sizes for specific occupations.


Approximately 1.1 million firefighters risk their lives protecting the public in the U.S.1 On average, 90 to 100 firefighters die in the line of duty each year.1 In 2013, firefighters suffered approximately 65,880, injuries. 2 Firefighters rely heavily on fire apparatus (i.e., vehicle) and personal protective equipment (PPE; i.e., bunker gear) to help protect them.

In 2006, the National Fallen Firefighters Foundation reported the need to consider firefighter body size and shape information when designing fire apparatus and PPE. A group of firefighter associations and fire apparatus manufacturers proposed a survey of U.S. firefighters to address fire-apparatus design issues and to update the National Fire Protection Association (NFPA) standards for apparatus and PPE. In response, NIOSH collaborated with the firefighter community, firefighter apparatus manufacturers, and the NFPA standards committee to plan and conduct a national survey on firefighter anthropometry during 2008-2012.

NIOSH collected anthropometry data from 951 firefighters in four U.S. regions (Rockville, MD; Philadelphia, PA; Phoenix, AZ; and Fort Worth, TX). As part of this study, 71 anthropometric dimensions were measured. The data obtained in this study provide the first available U.S. national firefighter anthropometric information for fire apparatus and firefighter PPE designs.

NIOSH produced a database that was shared with 17 firefighter associations and firefighter apparatus manufacturers to begin updating their designs of seat belts, fire truck cabs, gloves, boots, seats, self-contained breathing apparatus carrying straps, and protective clothing. NIOSH also developed and tested a series of design procedures, which provide the basis for equipment designers, standards writers, and industry manufacturers to use and improve PPE design and efficacy. Findings revealed that changes to fire apparatus and PPE sizing are needed to accommodate today’s firefighters.

Previous research has demonstrated that some firefighters are not physically able to buckle their seatbelt in emergency vehicles when in turnout gear. As a result, a fire department in a very large metropolitan area retrofitted older fire apparatus with new seatbelt systems based on the NIOSH data. The NIOSH national firefighter anthropometry data, along with the robust partnerships established throughout this effort, contributed to an NFPA standards update on seatbelt specifications, which resulted in science-based modifications to seatbelt length, configuration, and retracting systems.3 This standard guides manufacturers in their design process and fire departments in their purchase requirements. The improved fire apparatus and PPE designs will better fit future firefighters and help protect them against injuries and hazardous exposures.


Truck Drivers

In 2009, truck drivers experienced 16.8% of all transportation-related fatalities and 2% of the nonfatal injuries requiring days away from work, even though they only made up 1.0% of the U.S. workforce (BLS). Truck drivers average 41.5 hours per week behind the wheel.4 A well-designed truck cab can make a significant difference in the working conditions for a truck driver impacting both comfort and safety. For example, if the design of the truck cab is poorly fitted to the size and dimensions of the driver, the road may be less visible and driving controls may be more difficult to reach, which increases the risk of a crash and resulting injuries to the truck driver and others on the road.

Truck manufacturers do consider the body dimensions of truck drivers as they design truck cabs. However, until recently the most current body measurement data for truck drivers dated from the early 1980s. In 2006, NIOSH researchers began a 4-year study to measure the body dimensions of the current truck driver workforce. With the active support of multiple trucking industry partners, researchers were able to recruit a diverse group of nearly 2,000 truck drivers nationwide (including, but not limited to: California, Indiana, Kentucky, New Jersey, Tennessee, and Texas) and record their weight, height, and 33 other body measurements. These measurements showed significant differences between the current truck driver workforce and truck drivers 30 years ago.

This information has been shared with the trucking industry, and is being widely used to update and improve truck cab design. Knowing that 36% of collisions between trucks occur in blind spots around the vehicle, 4 truck manufacturers and 3 parts suppliers have utilized the data to create truck cabs with increased visibility and easier entry. The design software used in this effort is being updated with the new measurement information for use in truck cab design across the industry. In addition, the Society of Automotive Engineers has affirmed its plan to update multiple truck cab standards based on the new data. Each of these changes provides an important contribution to the safety and health of the nation’s truck driver workforce.

This research set a model for conducting similar studies of other special groups. For instance, NIOSH has finished collecting data on emergency medical services workers, and is gearing up to collect data on law enforcement officers. Do you know a truck manufacturer or firefighter service partner that could benefit from this information? Please let us know in the comment section below.

In our ongoing efforts to provide meaningful information to safety professionals, we would like to hear how safety professionals are using this information. We will ask for similar feedback in relevant blogs. Please provide input in the comment section below.

Hongwei Hsiao, PhD

Dr. Hsiao is the Branch Chief for the Protective Technology Branch in NIOSH’s Division of Safety Research


For more information see:


  1. NIOSH [2013]. Firefighter fatality investigation and prevention program [].
  2. NFPA [2014].Firefighter Injuries in the United States. []
  3. NFPA [2008]. NFPA 1901 Standard for Fire Apparatus, 2009 Edition. Quincy, Massachusetts: National Fire Protection Association (NFPA).
  4. BLS [2011]. Career Guide to Industries, 2010-11 Edition: Truck Transportation and Warehousing. Washington, DC: U.S. Department of Labor, Bureau of Labor Statistics, Safety and Health Statistics Program [].


Posted on by Hongwei Hsiao, PhD

4 comments on “One Size Does Not Fit All”

Comments listed below are posted by individuals not associated with CDC, unless otherwise stated. These comments do not represent the official views of CDC, and CDC does not guarantee that any information posted by individuals on this site is correct, and disclaims any liability for any loss or damage resulting from reliance on any such information. Read more about our comment policy ».

    So informative & creative blog… I’m feeling excited while reading it… Thanks for sharing this piece about driving!!!

    “Knowing that 36% of collisions between trucks occur in blind spots around the vehicle,”

    True, but car drivers should also pay attention and check if they are not in the blind spot. I know many people who don’t care about it and thinking that it’s truck drivers responsibility to check blind spots.

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Page last reviewed: April 14, 2020
Page last updated: April 14, 2020