Tactical Ventilation In Hazmat Responses

Firefighting and hazardous materials responses have much in common when it comes to tactical approaches, and this is especially true as far as ventilation is concerned. The importance of ventilating a building for fire attack is a high priority for firefighters advancing hoselines and firefighters involved in search and rescue. Not only does effective ventilation rapidly evacuate building spaces of heat and fire gases, it greatly aids in better vision along with the speed of response. It is simple: ventilation, when completed correctly and synchronously, saves lives.

The same can be said for ventilation when used in hazmat response as a tactical tool. Responders can effectively change a hostile environment, or one that is flammable, toxic, corrosive, or even one with poor vision, into one that is safe and far less risky. Working in obscured vision or in vapor clouds present immediately dangerous to life and health (IDLH) conditions and should be avoided at all times.

Perhaps the best way to do all of this is to use positive-pressure ventilation (PPV) through the use of blowers. Precautions for using blowers require that they be set up in safe outside positions in order to blow fresh air into a contaminated building, or even into the back of a highway trailer that has experienced a chemical spill. This can all be easily completed by trained and competent crews who may only be hazmat operations-trained personnel.

Hazwoper, the Occupational Safety and Health Administration (OSHA) regulations that set the safety practices at hazmat emergencies, mandates that an incident commander (IC) characterize an atmosphere at all hazmat events. Ventilating an unsecured area does not relieve the IC of this responsibility, but it does make it safer for responders who enter the area. Rather than allow responders to enter, and stay in, potentially flammable and toxic environments, even with monitoring instruments, still amounts to an encounter not too different from Russian Roulette. There are just too many variables that can all add up to extreme risk when these environments are encountered.

Personal protective equipment (PPE) selection can also be precarious when simultaneously dealing with flammable, toxic and corrosive atmospheres. Which garment should be selected with those hazards present? It is a difficult call at any such incident, but one that is much less complicated if the dangerous atmosphere is eliminated through ventilation measures.

Ventilation of an unwanted atmosphere will not make the source of the problem go away, nor will it complete the cleanup activities that may be required to mitigate the emergency. Ventilation will, however, make the atmosphere far more visible for the responders, safer to work in and, far less dangerous. Entry personnel still must be properly protected, to include their breathing routes along with their skin from contact hazards. Entry personnel will still need to monitor the atmosphere on all entries to verify the atmosphere is safe for work activities. As a result of these atmospheric concerns, ventilation has become an important hazmat response risk-management consideration.

Ventilation for hazmat response is not a panacea and there are precautions that must be considered:

  1. Consider where the contaminated atmosphere will be sent. Sending a contaminated atmosphere somewhere else is irresponsible until it can be absolutely verified. Responders need to thoroughly check where contaminants will travel and even consider verification through competent air-monitoring operations.
  2. Consider how the exhaust openings will be made before ventilation begins. Usually, doors and windows can be used as exhaust points for contaminated atmospheres, but there may be times when there is no natural opening for exhaust. Exhaust openings may need to be made and can be accomplished in van trailers, wood-frame buildings and other lightweight structures by making artificial openings. For rooms inside buildings with only one door, blowers can be set up to blow fresh air into the lower half of the door while the top of the door acts as the exhaust point. This setup would also require another blower to be set-up outside the structure to blow fresh air out of the building's exhaust point.
  3. Consider where the blowers must be set up to ventilate effectively. This requires coordination and communication with all ventilation crews before actual PPV deployment. Also consider the minimum PPE to be self-contained breathing apparatus (SCBA) and structural fire protective clothing (SFPC) for personnel who deploy blowers in the "hot zone."
  4. Consider how to safely start the blowers. When approaching the object to be ventilated, it is imperative to be on the upwind side and to use monitoring instruments to check for flammable gases. Blowers should be operated only in safe atmospheres and without risk of igniting atmospheres. Even after blowers are started, they should be constantly checked for continued operation in safe atmospheres. An option for PPV application is to attach flexible ventilation chutes or even disposable plastic tubing to the blowers to better focus the ventilation efforts and also keep each blower in a safe location.
  5. Consider controlling the ventilation rate. If interior spaces are filled with unwanted atmospheres that may be flammable, corrosive and/or toxic, releasing them to the outdoor open environment may cause exposure problems for the public. For this reason, consider releasing the unwanted atmosphere a little at a time in order to keep contaminants below safe exposure thresholds. Use appropriate monitoring strategies to assure that downwind contaminants are at safe levels. This strategy may take more time than you would like, but it may be the safest action.
  6. Consider ventilation as a means to creating a micro-climate. In order to control working within vapor clouds, it may be better to avoid being in the cloud in the first place. Consider using a blower to ventilate a work area of gases and vapors and increase visibility yet decrease risk. One example is to use a blower on the ground and directed to disperse vapors while working around a railcar's manway.

Essentially, PPV for hazmat response is smart in that it controls dangerous and unwanted atmospheres. It is creating a micro-climate that can better protect responders, helping to avoid use of bulkier PPE and carrying numerous and unnecessary air monitors, and it can also better protect exposed populations. Consider this tool at every hazmat event and with the precautions cited above, and use it intelligently.

DAVID F. PETERSON is a lieutenant in the Madison, WI, Fire Department, where he is the lead fire and hazmat training officer. He is in his 30th year as an emergency responder and is the managing member for the Wisconsin FLAME Group LLC. Peterson also operates www.hazmatpetie.com, a hazardous materials response training website. Please send your comments and questions to him at www.hazmatpetie.com or dcnkm@charter.net.