FPEeXTRAIssue33

Human Response and Notification — What Fire Protection Engineers Should Know

By Demi Omori

Most fire protection engineers are familiar with the recurring issue that building occupants do not respond to fire alarms as appropriately or efficiently as anticipated. This article provides basic guidance information about how to enhance human response to emergency communication, which can help engineers improve the design of emergency notification and messaging systems. This guidance can result in helping to reduce occupant evacuation time and increase life safety.

The 2016 NFPA 72® Appendix A provides related information about improving emergency communication. This guidance information was only recently included in NFPA 72®; there was little published previously about how to improve human response to emergency messages.

Over the years, the theory that people panic during an emergency has been replaced with the recognition that people require detailed information as early as possible. In fact, building occupants “rarely panic in fire situations” and “the behavior that they adopt is based on the information they have, the perceived threat, and the decisions they make,”1  per NFPA 72® Appendix A.

The Protective Action Decision Model [PADM] is a model published by the U.S. National Institute of Standards and Technology (NIST) that describes the information flow and decision-making that influences the actions taken in response to natural and technological disasters. This is a simplified version of the decision-making process.2

 

Figure 1: Simplified Decision-Making Process.

The decision-making process that occupants undergo during an emergency is based on external and internal conditions. The following guidance information can help improve occupants’ perception; attention to; and comprehension, confirmation and personalization of the emergency alert or warning message.

Alerts Guidance

Before a warning message is disseminated, an alert is necessary to grab building occupants’ attention. Here are selected guidance statements for alerts:3

  • Alerts should be significantly different from ambient sounds.

  • Building managers should reduce background noise when initiating audible alerts.

  • Flashing, rather than static, lights, preferably in one standard color for all buildings, can be used to draw attention to visual warning messages.

  • An alert signal should be accompanied by a clear, consistent, concise and candid warning message.

  • An alert should be tested for its success in getting occupants’ attention in the event of an emergency; such a test should be part of building-wide training.

Message Guidance

Warning messages should provide information to the building occupants about the status of the emergency and what they should do in response to this emergency. Warning messages can be provided via visual or audible means. These selected guidance statements can be used for warning messages.3

Message Content/Structure

  • Research from Mileti and Sorenson4 on communication of emergency public warnings found that a warning message should contain five important topics to ensure that building occupants have sufficient information to respond. These topics include:
    • Who is providing the message — the source of the message
    • What should people do — what actions occupants should take in response to the emergency; for example, whether occupants are to stay in place or not
    • When do people need to act — in rapid-onset events, the “when” is likely to be “immediately”
    • Where is the emergency taking place — who has to act and who does not)
    • Why do people need to act — including a description of the hazard and its dangers/consequences
    • Distinct audiences should be addressed separately in the message (or multiple messages).

Message Language or Wording

  • Messages should be written in the active voice, present tense.
  • Emergency messages should be written at a sixth-grade reading level or lower. An emergency message can be evaluated for its reading level using computer software and/or simple calculation.3

Visual Warnings

  • An ideal stroke-to-width ratio of the letters (ratio of the thickness of the stroke to the height of the letter/number) is 1:5 (generally), with a ratio of 1:7 suggested for lighter letters on a darker background. An example of the stroke-to-width ratio is:

  • Building managers or emergency personnel should consult the ADA Standards for Accessible Design5 for additional requirements on signage.
  • Contrast between the text and the background should be at least 30%, although recommended values could be as high as at least 60%.
  • Diagrams that display a series of sequential steps are more successful for comprehension of a process than one single graphic.
  • A warning message can increase in perceived credibility and risk if occupants can see that others are also responding.
  • Limit the use of flashing words on visual message displays.

Audible Warnings

  • Any voice announcements should also be accompanied by simultaneous visual text.
  • Message speakers (or sources) should not have heavy accents and should use a rate of approximately 175 words per minute.
  • Audible warnings should be delivered by a live voice.
  • Messages may have to be provided in multiple languages.

Message Dissemination

  • A live voice message in an urgent tone is more effective than a prerecorded message.
  • A familiar voice is best.
  • Avoid problems with impromptu phrasing and audibility, such as holding a microphone too close and speaking too fast — drills can reduce this potential for confusion or lack of understanding and reaction.
  • A warning message should be repeated at least once, with some research advocating for repeating a message at least two times.
  • Messages should be stated in full, and then repeated in full, rather than repeating elements within the same message.

Emergency communication is categorized into alerts and warnings. Alerts grab people’s attention and warnings provide information relating to the emergency and response.

Most of the guidance provided in this article originates from a NIST report written for the U.S. Department of Homeland Security.2

Demi Omori is with JENSEN HUGHES

References

1NFPA 72®, National Fire Alarm and Signaling Code, Quincy, MA USA: National Fire Protection Association, 2016.

2Kuligowski, E.D., S.M.V. Gwynne, K.M. Butler, B.L. Hoskins, and C.R. Sandler. Developing Emergency Communication Strategies for Buildings. NIST Technical Note 1733, National Institute of Standards and Technology: Gaithersburg, MD, 2012.

3E.D. Kuligowski and H. Omori, “General Guidance on Emergency Communication Strategies for Buildings, Second Edition,” National Institute of Standards and Technology, Gaithersburg, MD, 2014.

4D.S. Mileti and J.H. Sorenson, “Communications of Emergency Public Warnings: A Social Science Perspective and State-of-the-art Assessment,” National Laboratory, U.S. Department of Energy, Oak Ridge, TN, 1990.

5U.S. Department of Justice, ADA Standards for Accessible Design, Washington, D.C.: U.S. Department of Justice, 2010.