Talking about firefighter safety

With about 8,000 wildfires burning throughout Canada’s vast landscape each year, it goes without saying that a large number of resources are required to manage them. In this article, Greg Baxter from FPInnovations’ Wildfire Operations Research group answers questions about the work that FPInnovations is doing to help ensure the safety of the most important resource: the people working on the firelines.

What work has FPInnovations been doing related to the safety of firefighters?

GB:  FPInnovations has worked on numerous projects that have an impact on firefighter safety. Over the past two decades we have performed research on firefighter hardhats, foot travel rates for firefighters, and survival zones. Most recently, we just completed a 5-year project in which we investigated the collection and use of temperature lapse rate data.

What are survival zones and lapse rates, and how do they relate to firefighter safety?

GB: Let’s start with lapse rates. It’s a term used to describe the change in temperature with altitude and describes the stability of the atmosphere. The larger the change in temperature, especially in the lower 1000 m, the more unstable the atmosphere. There have been instances where wildfires have “blown-up” without any prior indications that they would happen. Post-fire case studies identified that very unstable atmospheric conditions existed at the time of the blow-ups. The sudden, unpredicted increase in fire behaviour is very dangerous for those working on the firelines. This data is currently being collected in a limited capacity in select locations by Environment Canada. This project seeks to expand the availability and spatial resolution of this time-sensitive information.

Could you describe FPInnovations’ project on lapse rates?

GB: We investigated methods for collecting temperature data above a wildfire and then transferring the data in near-real time to fire managers. The knowledge of the stability of the atmosphere could be an extra tool available to enhance firefighter safety.

We sourced a firefighting aircraft with an external sensor and used it to collect data over two very active fire seasons. After comparing this data against Environment Canada’s records to ensure their accuracy, we calculated lapse rates and identified a few examples of very unstable atmospheres and associated them in some cases with increases in fire behaviour. Another development was an inexpensive sensor made of off-the-shelf components. This sensor, which can be used to collect data for calculating lapse rates, can be attached to a drone which ground personnel can use on the fireline. An InfoNote that we published provides detailed information so that anyone can build the sensor, and it documents the process of moving the data from the aircraft to a server and then to ground personnel in order for fire agencies to collect and use the data as a safety tool.

You also mentioned survival zones. What are those?

GB: Survival zones are areas for firefighters to escape from a life-threatening situation, hunker down, and quite simply, survive. These are not the same as safety zones, which are large, open areas cleared of debris where firefighters (and equipment) can move to and take refuge. Survival zones are smaller openings where the firefighter will likely be in an uncomfortable situation and “feel the heat.” This research complements some work previously undertaken by our team that identified the factors that influence the speed at which firefighters can travel along escape routes to remove themselves from unsafe wildfire behaviour conditions.

What type of work has FPInnovations been doing on survival zones?

GB: We have been identifying guidelines that firefighters can use when they need to select and use survival zones as a last resort if they are involved in a burn-over or entrapment. To test survival zones, we first identified the survival limits of humans based on exposure to radiant heat. We carried out experimental fires in grass and forest fuels in constructed or natural openings, and established three plots within a wildfire in the Northwest Territories. Heat flux sensors collected data as a fire moved up to, around (or through), and past these openings. We began work in grass fuels as many fires could be done quickly to develop research methods, then moved into standing timber and shrubs and even included a burn on a steep slope in Jasper National Park.

What kinds of things determine a suitable survival zone?

GB: They should be open areas with little or no surface fuels available to carry fire or ignite due to embers. The size of the survival zone depends on the height of the surrounding fuel. We found that in grass fuels, 10-metre openings were sufficient in most of our test burns. In standing timber, 20 to 50 metres across openings were sufficient in our tests. We weren’t able to conduct fires in all fuel types or fire behaviour conditions but in general, the larger the opening, the better. As an example, a suitable survival zone in black spruce forests could be well sites in Alberta which are typically 120 x 120 metres in size.

When we did our investigations on steep terrain, we found that larger openings were required because flames would lean towards the slope and thus be closer to the ground. In general, grass fires require smaller openings than black spruce forests (10-metre trees), which in turn require smaller openings than pine forests (15-metre trees).

These are guidelines only and for worst-case scenarios. A key factor in all this is human behaviour. Being able to remain calm, move to a survival zone, and then lie prone is critical. Of course, the best option would be to heed accurate fire behaviour predictions so as to avoid such situations.

We have been investigating survival zones for several years and plan to complete the project this summer with a final experimental fire.

Related reports

Access to full reports on these topics is available through FPInnovations’ research library:

For more information, please contact Greg Baxter, Senior Researcher, FPInnovations’ Wildfire Operations Research group for more information.