Hazmat Survival Tips: Summertime Hazardous Materials Incidents

Beyond the Rule of Thumb
Survival Tip 53

By Steven De Lisi

It’s summer. Although first responders already enduring high heat and humidity during fire suppression operations don’t need to hear this, it is worth discussing how summer weather conditions can affect those dealing with a hazardous materials incident. High heat and humidity can have a negative impact on personnel and equipment and influence the behavior of chemicals and containers.  

Without a doubt, personnel wearing chemical protective clothing are at a high risk for heat-related illnesses. This warning applies not only to fully encapsulating vapor protective ensembles but also to liquid splash clothing and firefighter protective ensemble. Some ways to minimize the potential for negative health effects include adequate hydration of all personnel on scene. It is also important to encourage those on duty to be adequately hydrated even before an incident occurs. One nonscientific recommendation is to drink enough water throughout the workday (and even before coming on duty) so that your urine appears clear. Be careful not to drink too much water or other fluids; doing so can have negative health consequences as well.

Limit the work times for personnel. Although most hazardous material teams are well aware of the need for “air management” to reduce the likelihood that members of an entry team will run out of air, they may not be as aware of the importance of time management to minimize the potential for a heat-related illness during the summer. 

 

It is obvious that more personnel will be needed for more frequent crew rotations, but   the need for more protective clothing is often overlooked. Four two-person teams, each operating for no more than 10 minutes, will require eight suits. During cooler weather, you may be able to use only two teams operating for a total of 20 minutes each. You would need only four suits.

 

What is the number of different types of chemical protective clothing in your inventory today? Could you support frequent crew rotations? Some suits can be reused, but only after a thorough cleaning and inspection. Remember, a suit could have been damaged during use or doffing and the inside is likely wet with perspiration from the previous user. Could you provide the level of cleaning and inspection needed on scene to ensure that the suit is safe for reuse?  

 

If you need more personnel than those available from your department, you may be able to rely on a mutual-aid agreement with members of a nearby hazardous materials team. However, if those coming to assist are unfamiliar with the chemical protective clothing your department uses, there could be some serious safety concerns. The time to plan for mutual-aid personnel is before an incident, not after when you are doing so only to fulfill a recommendation from a critique of an incident that did not go well.    

 

Team members should be housed in a cool, preferably air-conditioned, location prior to entry. The location may be inside of a building, an ambulance, or a command post vehicle. Avoid having team members dress out in the middle of an asphalt parking lot during periods of high heat and humidity. Although large tents used to shield team members from direct sunlight are useful, allowing personnel to remain cool and dry during the donning process is vital for their health.   

Temperature affects almost all chemicals. The potential for chemicals to react and undergo changes increases as the temperature of the material increases. In addition, materials with greater volatility may produce higher levels of dangerous vapors at elevated temperatures. When dealing with liquids, those with high vapor pressure and low boiling points should be of particular concern. Also, first responders should be aware of a material’s melting point, if any, when dealing with solids. 

Remember, too, that spilled liquids and solids are affected not only by ambient temperature but also by the temperature of the surface on which they are lying. Although it may be 95° outside, the temperature of the asphalt onto which a chemical has spilled could be many degrees higher and, therefore, present a greater likelihood of influencing that chemical’s behavior.         

 

Depending on the volatility of a chemical, increasing the temperature to which a container is exposed can increase the internal pressure exerted on the container. This can activate the pressure relief device, thereby releasing the contents. If the relief device is not designed to close (or does not close because of a malfunction), the entire contents of the container may be released. Depending on the quantity and nature of the material, the safety of personnel and the public could be seriously jeopardized.  

 

While anticipating the potential for a relief device exposed to high heat to operate, cooling containers with water is always an option, though this could be difficult if water supplies are limited. Another option is to move containers from an area of direct sunlight into one that is shaded; do this with caution, since doing this may place personnel in close proximity to the containers. 

 

Some containers exposed to high heat may bulge, and those made of metal may exhibit a metallic “pinging” sound as internal pressure increases. This increase in pressure could also cause caps and lids pop off. First responders attempting to remove a lid from a container of liquid exposed to high heat should slowly turn the lid to loosen it while listening carefully for the sound of escaping vapor. To prevent the cap from popping loose, allow all of the vapors to escape before you continue your efforts to remove the lid.

 

Remember that the sound of escaping vapors indicates not only high internal pressure but also that the material likely has a high vapor pressure and that, under the current atmospheric conditions, will produce a large quantity of vapors. If these vapors are flammable or toxic, the potential for dangerous exposure for anyone nearby will increase.          

 

One way to minimize problems associated with working with overheated containers is to adjust operating times to overnight hours, when outdoor temperatures are likely to be lower. Of course, you may not be able to wait if the emergency incident involves the release of a hazardous material from a damaged container. However, if, for example, you are obtaining chemical samples during the investigation of an environmental crime scene, waiting until sunset to obtain these samples could present fewer risks to personnel because of the decreased internal pressure exerted on containers and reduced heat stress.

 

Night operations raise the issue of limited lighting and visibility, which can usually be resolved with overhead lighting. Remember that for some hazardous material incidents, it may be better to rent mobile light units from an industrial supply company rather than position expensive fire apparatus in close proximity to chemical containers.  

 

A final note when dealing with containers and chemicals exposed to high ambient temperature involves pressurized containers of liquefied and nonliquefied gases that have been damaged during an incident. This damage may appear as a dent, gouge, or a crease and could severely undermine the container’s structural integrity. Keep in mind that this damage could be on the underside of a tank and not readily visible to first responders. 

 

Some may believe that the container’s pressure relief device will prevent the container’s explosion from increased internal pressure, but remember that the damaged area may be able to withstand only pressure that is less than the setting of the relief valve. Therefore, the damaged area is the “weak link” in the container and may rupture and release product long before the relief valve would normally do so. 

 

Consider that it may be no more than 73º during the early morning hours when you arrive on the scene of an overturned pressurized highway cargo tank. However, it could be 98º later in the day, a 25° increase in temperature. As the liquid in the container heats up, will the increase in internal pressure cause the container to rupture as a result of damage inflicted during the incident?       

 

Other damage to be aware of is rust and corrosion on the container’s exterior; they could be on the inside walls as well. During one incident that occurred during August, a rusty compressed gas cylinder was unearthed at a construction project. Workers there took the cylinder, which had been buried under cool and moist dirt for years, and placed it out of their way, unfortunately, in an area of direct sunlight. The potential for a catastrophic explosion and the release of an unknown chemical from an unmarked container was extremely high. First responders arriving on scene evacuated the work area and sprayed water on the cylinder from an unstaffed nozzle placed at a distance. Efforts to recover the cylinder were suspended until evening.       

Protecting the public during summer months can present some unique challenges to first responders. Probably the greatest challenge involves the sheer number of people who are outdoors. It is much easier for an instructor in an emergency management training program to recommend “protect in place” than it is for first responders to accomplish this in the real world. Consider an urban area when many of those working in high-rise office buildings escape during lunch to enjoy the weather on a sunny weekday afternoon. Under these conditions, the potential for a large number of people to be exposed to a hazardous material vapor cloud is far greater than it would be on a day of cold driving rain in January. Other examples include large gatherings at outdoor concerts, beaches, and sporting events. Simply put, more people outdoors presents the potential for more exposures.     

Another weather issue related to protecting the public is that despite the popularity of central air-conditioning, many people prefer natural ventilation through open windows. Although air-conditioning does not eliminate the threat to a building’s inhabitants from airborne chemicals, those with open windows are at far greater risk, especially while sleeping. Unfortunately, first responders have no way to know which buildings in an affected area are more susceptible because of open windows.

 

The prevalence of waterborne activities during the summer can also present a great challenge to first responders attempting to remove people from beaches, creeks, streams, and ponds that may be affected by a chemical spill. Once an area has been evacuated, keeping others from entering can be an even greater challenge. Barrier tape does not work for those who believe that unless their name is printed on the tape, the warning must apply to someone else. In situations such as these, law enforcement personnel, especially park rangers and game wardens, may be necessary to ensure the public’s safety.   

 

Those who don’t believe that politics plays a role when dealing with a hazardous materials emergency should attempt to close a popular recreational attraction during a summertime holiday weekend. Believe me when I say they will need a lot of backup from local government leaders and politicians, who will hopefully take the grief for your decision. Remember that if you don’t restrict access to a potentially contaminated area because you fear the political, financial, and multimedia backlash, you will likely lose anyway when the first person to get sick wants to know why you allowed them into such a dangerous area.              

 

Additional concerns related to operating during hot summer weather include the strain placed on internal combustion engines that can overheat because of the long-term nature of many hazardous materials incidents. Frequent attention must be paid to the operating temperature of these engines, especially those engaged in providing water.

 

Of course, the need for regular inspections of coolant levels cannot be overstated. Some first responders forget that when dealing with engine coolants, their concern should be not just protecting the coolant from freezing; they should remember that most coolants contain chemicals to prevent overheating as well. However, this protection is diminished if over time first responders repeatedly add plain water to the engine’s cooling system to maintain the proper fluid level. If you need to add coolant, check with your vehicle maintenance personnel to obtain the correct refill solution and if you need to add coolant frequently, have the system checked for leaks.     

 

Thunderstorms are another fact of life during summer. Some of them, especially those that occur during late afternoon and early evening, can be severe. In addition to the danger of a lightening strike, heavy thunderstorms can disturb chemical containment booms, cause containment areas to overflow, and allow chemicals to flow downstream and impact storm water and sanitary sewer facilities. Stay alert for weather forecasts, and remember that there is little that can be done to counteract the effects of a driving rainstorm. The best you can do is to protect personnel and equipment from rain and lightening by sheltering in a nearby building or in a large vehicle such as a school bus and to plan in advance where a chemical spill will go if it is washed away from the scene. Although some believe that heavy rain is a good thing, remember that the mindset of “dilution is the solution” will not always be appropriate; it depends on the chemical involved. 

Although there is much that can be done to protect personnel and equipment during the summer months, nothing will ever take the place of common sense when dealing with high heat and humid conditions. Remember, too, that there is no such thing as a routine hazardous materials incident. As experienced first responders know, every incident is unique and summer incidents always require an extra level of care and attention to ensure that everyone goes home.  

Questions or comments on this or any other monthly Hazardous Materials Survival Tip may be directed to Steven De Lisi at HazMatSurvivalTip@comcast.net.

Steven M. De Lisi recently retired from the fire service following a 27-year career that included serving as the deputy chief for the Virginia Air Guard Fire Rescue and a division chief for the Virginia Department of Fire Programs (VDFP). De Lisi is a hazardous materials specialist and as an adjunct instructor for VDFP; he continues to conduct hazardous materials Awareness- and Operations-level training. De Lisi began his career in hazardous materials response in 1982 as a member of the hazmat team with the Newport News (VA) Fire Department. He has also served as a hazardous materials officer for the Virginia Department of Emergency Management. De Lisi has a master’s degree in public safety leadership and is the author of Hazardous Material Incidents: Surviving the Initial Response (Fire Engineering, 2006).

Click here for more info on Steven De Lisi’s book, Hazardous Materials Incidents: Surviving the Initial Response.