Technological advancements in building materials and construction practices have changed the response environments and practices for structural firefighting in terms of heat load, toxic substances and a greater diversity of hazards. Likewise, the increasing availability of electric vehicles (EVs) and hybrid electric vehicles (HEVs) have created the need for changes in emergency response to vehicle accidents.
The United States has set a goal for having 1 million EVs on the road by 2015, and China has stated that 500,000 new-energy vehicles will be in production by the end of 2015. Undoubtedly, these will become increasingly more common over the next several years and so will be the proportion of these vehicles involved in accidents.
When these vehicles are involved in severe crashes there are potential hazards from the battery systems on board. Car manufacturers design EVs to provide protection and electrical isolation of the battery system, but under some accident conditions battery-safety features may be compromised.
In testing last year, one manufacturer reported EV fires broke out days or even weeks after the National Highway Transportation Safety Administration crash tested its lines of EVs where the crashes severe enough to damage the battery.
NHTSA is investigating the hazards associated with EVs and working with other organizations such as the National Fire Protection Association and Society of Automotive Engineers to develop standards and best practices related to emergency responses that also address personal protective equipment.
Lithium hazards
On Aug. 8, USA Today published “Cars safer for passengers — but not first responders” highlighting the challenges facing emergency workers involved in conducting safe and effective rescues for electrified cars and other new automotive technological changes. A large portion of these issues have arisen based on concerns on the make-up of lithium-ion (Li-Ion) batteries, which are the same batteries of choice used in cell phones and lap top computers.
These batteries have a relatively high energy density and use a flammable solvent as the electrolyte that aids ion movement in the battery cells during charging. The NFPA has reported the rare, yet potentially dangerous, circumstances leading to battery failure, including poor cell design or defects leading to short circuits, cell manufacturing flaws, external abuse of cells, and charging inadequacies.
There is a phenomenon where rapid self-heating of a battery cell, known as thermal runaway, may cause the electrolyte to combust, potentially spreading fire to other battery cells or venting flammable vapors. A complete report on Li-Ion battery hazards is provided by the NFPA.
High voltage
Of course, at a vehicle accident, it is important to be able to identify an automobile as being an EV and determine if it is still energized, which can be very different from how responders approach gasoline- or diesel-fueled vehicles.
Some EV propulsion systems operate at much higher voltages than regular automotive batteries and may discharge electric current when the cables or insulators are damaged. Loss of integrity for the battery compartment and the battery itself can release electrolyte, a fuel for fire.
While EV accidents may present unusual problems, such as fires and fumes resulting from rapid battery discharge, there is apparently no available information regarding whether they are inherently more or less dangerous than gasoline- or diesel-powered vehicles, which carry flammable fuels.
Available research
With the ongoing NHTSA investigation of EV safety, significant attention is also being given to primary and secondary emergency responder safety. SAE has established a Hybrid and EV First and Second Responder Task Group to develop a Recommended Practice (SAE J2990) to provide common practices for response personnel. It is expected that some of this work will advance PPE recommendations.
The NFPA has developed interim guidance in its report “Electric Vehicle Emergency Field Guidelines” and has created a training program for first responders.
NFPA sells the report through its website.
The report provides basic recommendations for scene survey, scene management, securing the scene, patient care, and extrication. Some information is provided for fire suppression and PPE, but most of this information is on the various individual vehicle pages that give the car manufacturer recommendations.
A review of this information shows that many car-maker recommendations are inconsistent and incomplete. For example, some manufacturers indicate that conventional turnout gear is adequate while others advocate using insulated clothing typically suited for the electrical utility industry for protection against electrical arc.
Furthermore, some aspects of emergency response, such as hazard zones, are not yet adequately defined. As a consequence, first responders still need to understand the adequacy of personal protective equipment and have appropriate procedures for protecting themselves and the victims during EV accidents.
PPE capabilities and potential gaps
In order to understand the state of turnout gear or technical rescue gear suitability for EV accidents, it is important to recognize how protective clothing and equipment for structural fires has been standardized through requirements in different NFPA standards that cover this gear. Of note are the following:
- Protective clothing for structural firefighting compliant with NFPA 1971 is designed and testing for general fireground hazards and cannot take into account all anticipated exposure conditions.
- The only elements of the structural firefighting ensemble evaluated for electrical resistance are the helmet and footwear with testing that has been primarily based on possible contact with an energized electrical line within a structure. Garments, gloves and hoods are not similarly tested.
- Barrier materials in garments, gloves and footwear are evaluated for liquid penetration resistance, but are not direct barriers to vapors or gases. One of the liquid-penetration test chemicals is battery acid, or 37% sulfuric acid, but EV battery solutions are not included in the test.
- Technical rescue protective clothing specifications in NFPA 1951 are generalized to various emergency operations, including vehicle victim extrication. Only the ensemble elements that have been certified to the rescue and recovery requirements of the standard provide any kind of liquid barrier protection. As with NFPA 1971, only NFPA 1951-compliant helmets and footwear is tested for electrical resistance.
Clearly, more work is needed to adequately address questions for PPE effectiveness against electric and hybrid vehicle hazards. As with any new hazardous situation, the fire service must be vigilant in recognizing emerging hazards and understand the limitations of their PPE.
