• NIST research has improved firefighting equipment standards, leading to fewer malfunctions.
• NIST has also led research on how heat and air move through a burning building, leading to better tactics the fire service now uses in fighting fires.
• This work continues to make firefighting safer and more effective.

Firefighting is a dangerous job. In order to stay safe and do their jobs well, it’s important for firefighters to have reliable equipment and effective fire suppression tactics. Over the years, NIST researchers have studied firefighting gear to reduce the risk to emergency responders. Here are a few examples.

Personal Alert Safety Systems (PASS)

When entering a dangerous area, firefighters wear a PASS device. It’s a small box that makes a loud noise if a firefighter is in trouble so that their teammates can quickly find them and help. It’s a critical piece of equipment, and firefighters have died when their PASS didn’t work correctly.

NIST staff found that at high temperatures, some PASS devices stopped working properly, putting the firefighters who used them in danger. Based on this research from NIST, in 2007 the standard for PASS devices was updated to require that they work well in the temperatures a firefighter might face.

Thermal Imaging Cameras  

It can be difficult to see in a smoke-filled room. A thermal camera can help a firefighter find people and fire sources they can’t see otherwise. But these cameras can be expensive, so it’s important for fire departments to carefully consider which one to buy.

To help them make that choice, NIST staff developed ways to measure and test them. In 2010, those tests were used to make the first official standard on thermal imagers for the fire service.

Portable Radios

Two-way radios are an important tool for firefighters, as they need a reliable way to communicate quickly during an emergency. But some firefighters noticed that their radios didn’t always work in the field. NIST staff investigated the issue and discovered that at the elevated fireground temperatures, most firefighter radios stopped working.  

Data from these studies and input from the NIST researchers provided the foundation for a new standard on firefighter radios.

Self-Contained Breathing Apparatus (SCBA)

Smoke is poisonous and dangerously hot, so firefighters wear face masks connected to tanks of clean air. After a series of experiments, NIST staff members discovered that a quick and dramatic change in temperature, as sometimes happens in a fire, could cause a facemask to become cloudy and hard to see through or even break entirely.

The staff then developed a test and performance criteria to update the standard for firefighters’ breathing equipment to withstand more intense conditions.

Fire-Dynamics-Based Firefighting  

Between the 1970s and the 2000s, fire researchers noticed a troubling trend: Even though the number of building fires was cut in half, more firefighters were dying in the line of duty. During that same period, firefighter fatalities increased by two-thirds.  

There were a few major changes to the typical American home that made house fires more dangerous. For one, houses were built with lighter materials that could catch fire more quickly. They were also built with larger rooms that were better at trapping air inside. This was better for energy efficiency, but in a fire it could create large pockets of fresh air that cause a sudden blast of heat when released.

On top of that, furniture had changed. Modern synthetic fabrics and cushioning foam burn more quickly than older materials.

To fight back against these more dangerous fires, NIST staff members have conducted research with the fire service to begin applying fire dynamics to firefighting.  

Fire dynamics is the science of how fires start, spread, develop and extinguish. At the core of this new field of research was learning how air moves through a burning building.

A fire that’s running low on oxygen suddenly burns faster when a new supply of fresh air arrives. During a fire, a firefighter might break down a door or pump in air to clear out smoke. This new air supply feeds the fire and makes it hotter. Understanding this led to an important rule of thumb for firefighters: Keep the airflow at your back. This tactic makes it more likely that a firefighter will be able to see and avoid sudden bursts of flame.

But it’s not always possible to predict sudden changes in airflow. For example, heat from a fire can break a window, causing a rush of air while responders are already in the building. Even with the best protective clothing and safety equipment, a fire fed with plenty of oxygen can simply get too hot for a person to survive.

To reduce the danger, NIST’s full-scale tests found that it’s important to stream water into the building before entering. This cools the fire and the air enough to significantly reduce the chance that if a window breaks, the air that rushes in will cause a sudden rise in heat to a deadly level.

Fire in a wood-framed basement is a particularly dangerous scenario. NIST found that the large mass of burning wood can get extremely hot while staying insulated from the floor above. Even with thermal cameras, firefighters might be unaware of the fire below until they fall through the floor.  

Before NIST’s research, firefighters tackled basement fires by pushing their way down the stairs. This was extremely dangerous because it placed them in the airflow path from the fire in the basement to the open front door. Because of the fresh air, fire on these stairs is particularly hot.

NIST and Underwriters Laboratories (UL) conducted basement fire experiments and found that applying water through a basement window into the fire area for just 60 seconds quickly mitigated the hazard of a collapsing ground floor as well as dangerous conditions on the stairs down to the basement.  

These are just a few examples of how NIST’s research on firefighting tactics has spawned a new approach to fire operations based on the science of fire dynamics. NIST staff members worked hard to spread the information they learned through reports, videos and presentations. Now the tactics they helped develop have been incorporated into training programs for firefighters throughout the United States

Additional Reading:

NIST publication: Thermal Environment for Electronic Equipment Used by First Responders, 2006.  

NIST publication: Performance of Thermal Imaging Cameras in High Temperature Environments, 2007.  

NIST publication: Performance of Portable Radios Exposed to Elevated Temperatures, 2014.  

NIST publication: Thermal Performance of Self-Contained Breathing Apparatus Facepiece Lenses Exposed to Radiant Heat Flux, 2013.

Journal article: Fire Dynamics: The Science of Fire Fighting. International Fire Service Journal of Leadership and Management, 2013.