Examining Carbon Dioxide Sensitivity in Firefighters

In the summer of 2021, I was fortunate enough to intern with a company that focused on creating breath-based interventions to improve performance and sleep, reduce anxiety, and better manage stress. They have worked with the military, Olympians, and CEOs, and in my specific project, we worked with firefighters. I got to interview firefighters from around the world about what they struggled most with and brainstorm ways that we could implement a variety of breathing protocols to help. I found this work to be incredibly rewarding and fun to meet all sorts of really great people. So, I decided to continue down this path with my Senior Thesis.

In collaboration with the Professional Firefighters Association of Maine, I was able to collect data from 117 firefighters from across the country. Through close work with Amy Davenport-Dakin from the PFF Maine Peer Support team and New Perceptions, I was able to come up with a study that offered insights and help to the fire unions. Specifically, I looked into the relationship between carbon dioxide sensitivity, affective symptoms such as anxiety, depression, and PTSD, and exposure to traumatic events. Carbon dioxide sensitivity is a measure of how well an individual tolerates the build-up of carbon dioxide in their bloodstream. CO2 hypersensitivity has been linked to Panic Disorder, Major Depressive Disorder, Generalized Anxiety Disorder, and Post-Traumatic Stress Disorder. All of these disorders have heightened prevalence rates in firefighters compared to the general population.

For some background, carbon dioxide is produced in the bloodstream as a byproduct of metabolic processes in our bodies and is removed via exhalation. Physical activity, stress, and perceived stress can cause an increase in the production of CO2. This build-up of CO2 in the bloodstream, not a lack of oxygen, is what tells our brain to increase our breathing. In fact, without enough CO2, the human body cannot use all of the available O2, so it is a constant balancing act. Too much CO2, and we breathe more to get rid of it. Exhale too much, and now our bodies cannot utilize all the O2in the blood, resulting in less efficient fuels being used. Furthermore, our breath is intimately connected with our stress and anxiety response, and an increase in breathing is correlated with an increase in anxiety and stress.

Through our research, we found that greater CO2 sensitivity was linked to greater prevalence of affective symptoms, supporting previous literature. Additionally, we found that the longer an individual had been in the fire service, the greater their CO2 sensitivity, regardless of age. However, one of the biggest surprises was how much higher the prevalence of these affective symptoms was in this population compared to previous firefighter populations. One potential explanation for this is the COVID-19 pandemic. Much of the existing literature was published prior to the onset of the pandemic, and research has already been published demonstrating the increased stress placed on first responders during the pandemic. These findings taken together demonstrate that this population, especially at this time, could benefit greatly from interventions aimed at mitigating the mental and physiological impacts of working as a firefighter. In fact, the data was used by PFF Maine in public testimony for a PTSD bill in Maine.

The full thesis as well as an executive summary were distributed to PFF Maine, as well as several fire departments from across the country for their own use. I was very grateful to be able to work alongside such great people and to produce something that could benefit them and be used beyond the Bates campus to help others.