New research published in Journal of Occupational and Environmental Hygiene (JOEH) suggests that fire departments can reduce stress on firefighters by signaling emergencies with alarms that gradually increase in intensity instead of sudden, full-volume alerts. The article, “Effect of Station-specific Alerting and Ramp-up Tones on Firefighters’ Alarm Time Heart Rates,” comes on the eve of the 35th Annual National Fallen Firefighters Memorial Weekend, Oct. 8–9, which honors firefighters who died in the line of duty during the previous year.
Authors James J. MacNeal, David C. Cone, and Christopher L. Wistrom note that of the 97 firefighters killed in the line of duty in 2013, 32 died from overexertion, stress, and related medical issues. In the last five years, heart attacks accounted for two-fifths of on-duty deaths. Previous studies have established that firefighters are more susceptible to heart attacks when responding to emergencies versus non-emergencies.
This study was conducted over three months and involved 42 firefighters at an urban three-station fire department. Firefighters participating in the study wore devices on their wrists that measured their heart rates. Researchers analyzed participants’ heart-rate increases in response to standard alerting—the sudden, high-volume alarms—and to alerts that gradually “ramp up” the audio volume. Study results showed that standard alerting caused a median increase in heart rate of 7 beats per minute (bpm), while the ramp-up tones caused a median increase of 5 bpm. In a post-study survey, participating firefighters indicated a strong preference for the ramp-up tones.
“Ramp-up tones were also perceived as the best alerting method to reduce stress during both the day and overnight,” the authors write. “This study suggests that the manner in which firefighters are alerted does have an influence on their physiologic response to the alarm.”
A number of long-term health effects are suffered by emergency responders, some influenced by psychological stress and fatigue. This study explored if stress and fatigue can be reduced by changing the method by which firefighters are alerted to emergency responses.
Over several months, the method by which responders at a fire department were alerted was altered. Firefighter heart rates were measured first with standard alerting as a control (phase 1: all stations alerted simultaneously, with high-volume tones). The department then implemented station-specific (phase 2) and gradual volume ramp-up (phase 3) tone alerting, and heart rate increases were compared. The Fatigue Severity Score was used to examine firefighter fatigue, and the department administered a follow-up survey on personnel preferences.
Individual heart rate increases (Δbpm) ranged from 2–48 bpm. Median increases were 7 bpm (IQR 4–11 bpm) during phase 1 (72.2% of alarms Δbpm<10), 7 bpm (IQR 5–12 bpm) during phase 2 (60.7% of alarms Δbpm<10), and 5 bpm (IQR 3–8 bpm) during phase 3 (82.7% of alarms Δbpm<10). The difference in medians was lower for phases 1 and 2 than for phase 3 (p = 0.0069), and more alarms in phase 3 resulted in increases of <10 bpm than in phase 2 (p = 0.0089). The Fatigue Severity Scale showed little variability: median scores 7 in phase 1, 8 in phase 2, and 7 in phase 3. Firefighters reported a strong preference for the “ramp-up” tones, and were roughly evenly divided between preferring alerting all stations simultaneously 24/7 (40% rating this 4 or 5 on a five-point Likert scale), station-specific alerting 24/7 (47.5%), or all stations during the day but station-specific at night (40%). Ramp-up tones were perceived as the best method to reduce stress during the day and overnight.
Small but significant decreases in the amount of tachycardic response to station alerting are associated with simple alterations in alerting methods. Station-specific and ramp-up tones improve perceived working conditions for emergency responders.
Read the full study in the Journal of Occupational and Environmental Hygiene. Please contact Mark Nicas, PhD, CIH, EditorinChief of JOEH, at firstname.lastname@example.org with questions or comments.
Image: Warwickshire Fire and Rescue Service from Warwickshire News