The use of hazard control zones is not a new concept in the fire service. Most typically, the fire service associates these zones, designated hot, warm and cold zones with hazmat operations. However, NFPA 1500: Standard on Fire Department Occupational Safety, Health, and Wellness Program has specified the use of hazard control zones for structural firefighters for some time.
While it is obvious that operations in hot zones require full firefighter PPE where hazards and risks are the greatest, many firefighters are unsure as to the type of PPE that should be worn in the warm zone. Given concerns for exposure to products of combustion that are either airborne or occur through contact with contaminated items, increased guidance is needed for defining what PPE should be worn outside the hot zone.
Understanding control zones and exposure hazards
The current edition of NFPA 1500 (2018) provides the following definitions for control zones:
- Cold zone: The control zone of an incident that contains the command post and such other support functions as are deemed necessary to control the incident.
- Warm zone: The control zone outside the hot zone where personnel and equipment decontamination and hot zone support takes place.
- Hot zone: The control zone immediately surrounding a hazardous area, which extends far enough to prevent adverse effects to personnel outside the zone.
NFPA 1500 further defines a “No Entry Zone” as “those areas at an incident scene that no person(s) are allowed to enter, regardless of what personal protective equipment (PPE) they are wearing due to dangerous conditions and ‘Collapse Zones’ where there is an imminent threat in an area that can cause exposure to trauma, debris, and/or thrust should a building or part of a building collapse.”
Relative to exposure hazards and PPE, NFPA 1500 notes the following:
- 18.104.22.168 Hot Zone (red tape), the area presenting the greatest risks to members, will often be classified as an IDLH atmosphere, and presents the highest risk of human injury and/or exposure; therefore, all members shall wear all of the PPE appropriate for the risks that might be encountered while in the hot zone.
- 22.214.171.124 Warm Zone (yellow tape) shall serve as a limited access area for members directly aiding or in support of operations in the hot zone where significant risk of human injury can still exist.
Thus, as written currently, the hot zone is the only zone where PPE is mandated. However, changes have been proposed to the next edition of NFPA 1500 that entail establishing control zones for purposes of contamination control. These include indicating that the hot zone is also the area of the emergency scene with the greatest likelihood of contamination exposure, where preliminary exposure reduction (what some in the fire service refer to as “on-scene gross decontamination”) is to be carried out in the warm zone, limiting access to the warm zone for the purpose of limiting cross-contamination, and stating that the cold zone is the area of the emergency scene outside any areas where contamination is being mitigated.
This new approach has implications for PPE use in the warm zone.
Firefighter PPE for the warm zone
The 2020 edition of NFPA 1851: Standard on Selection, Care, and Maintenance of Protective Ensembles for Structural Fire Fighting and Proximity Fire Fighting states that firefighters should wear full PPE for preliminary exposure reduction (PER), meaning that each firefighter wears all of his or her gear, until after the wet or dry mitigation process has been finished. This is to ensure that all easily removed contamination can be removed from the PPE items to make doffing safer and minimize as much as possible contaminant transfer to the individual firefighter. It is particularly important to have firefighters continue to wear their SCBA because many hazardous chemical contaminants will be off gassing and if a dry mitigation technique is used, involving brushing off the exterior of the ensemble, then the firefighter won’t be exposed to airborne particles that are released during the brushing process.
[Read next: PPE preliminary exposure reduction for firefighters]
While not popular (the first thing firefighters want to do is take everything off after the fire), this make sense. Yet, what should everyone else be wearing in the warm zone for contamination control? There is still handling of the PPE yet to be fully cleaned, dirty tools, hose and the potential for smoke exposure.
Certainly, some form of PPE should be worn to minimize contaminant transfer, such as disposable gloves for handling contaminated items before the contaminated items are either cleaned on scene, bagged or otherwise isolated. Contamination transfer to firefighter skin can further be mitigated by individuals in the warm zone wearing structural gear. Yet, the bigger question is respiratory protection.
Some smoke exposure is possible for individuals who operate in the warm zone, whether as a pump operator or providing on-scene support. While apparatus in these operations are generally positioned to be away from direct inhalation of smoke, wind direction changes and firefighters’ activities on the fireground can result in exposures.
For example, pump operators can get relatively close to the hot zone depending on their specific fireground duties. The question thus arises whether certain individuals should be wearing SCBA and when, or if there are alternative respirators to be worn that are subject to their own requirements and limitations. Right now, fire service occupational health and safety experts are debating best practices for protecting firefighters, but it does help to show one case where a difference was found by wearing SCBA.
Case in point: Tucson study of engineers’ exposure
The Tucson Fire Department in conjunction with University of Arizona Mel and Enid Zuckerman College of Public Health undertook a FEMA-funded study where they investigated the effectiveness of different intervention methods for reducing contamination of firefighters. One of the interventions was having engineers (pump operators) wear their SCBA while on air during fire operations.
During several working fires, the measurement of a specific carcinogen metabolite 1-Naphthol (for the polycyclic aromatic hydrocarbon naphthalene) found in urine was measured for firefighters both wearing and not wearing SCBA. These measurements were compared to firefighters with no fireground exposure that established baseline levels.
The results of this testing showed post-fire 1-Napthol levels to be three times those of post-intervention levels. Further, the post-intervention results were nearly identical to the baseline (no exposure) results.
This study showed that for engineers, the principal warm zone exposure to contamination is through inhalation and that wearing of SCBA on the fireground reduced their exposure to one type of known harmful airborne contaminant. (Note: This work will be published in a peer-reviewed journal article in the near future.)
Resolving warm zone PPE decisions
Clearly, contamination control is taking many forms with different best practices. These include obvious changes, such as ensuring proper PPE wear in the hot zone, cleaning PPE more frequently, and practicing good hygiene post-fire. All of these practices help to reduce the overall contamination transfer possible following a structure fire.
A gray area remains for the warm zone, where contamination control is still needed. The introduction of small changes to operating procedures in the warm zone is yet another set of practices for controlling contamination – all part of the overall strategy for reducing harmful firefighter exposures.
Note: The views of the author do not necessarily reflect those of the sponsor.