Last week, we looked at the technical issues and elements that must be considered when responding to a toxic cloud emergency. Most toxic clouds occur when an industrial fire occurs, or when there is a major accidental release of dangerous gases from a fixed facility, or from a ruptured pressurised cylinder.
Most gases are kept in pressurised cylinders; however, gases may also be released when some chemical solids come in to contact with water. For example, white phosphorous on contact with air will violently react, bursting into flames, becoming both a flammable and a respiratory hazard to plant, animal and human life regardless of the time of day. This week I present some answers to last weeks’ questions.
What are the suitable methods of protection that must be utilised by responders while doing their job?
The only answer to this question is equipment and training. As simple as this may appear, no matter how much equipment is given to a person, unless he/she understands the limitations of that equipment, improper usage of that equipment can be just as life threatening as not having any equipment in the first instance.
There are various levels of equipment protection established for responders; each level dictates what equipment must be worn, its durability, its exposure time, and the level determines what training must be conducted in order to ensure competency of its use. Any person can be given protective equipment but without the appropriate training, that equipment will also become a hazard.
It is internationally recommended and in some countries, it is mandatory, that all responders achieve certified competency and possess the required experience in chemical protective equipment. Every scenario must be examined; every modality must be considered before responding, each hazard will dictate which equipment type will be required by responders before proceeding to the site.
Will the residents in the immediate vicinity of a toxic cloud need to be evacuated for their own protection?
Residents need not be moved in all cases. In fact, unless the cloud has been determined to contain radioactive particles, or is slow moving and very low to the ground, there are methods that can be employed that will provide the required protection without moving. Evacuating residents is an extremely complicated process when used as a protective mechanism in public safety. In flooding, residents are required to move to higher elevations beyond the reach of the floodwaters; with volcanic eruptions, evacuations are mandatory, as a pyroclastic cloud will destroy anything in its path.
Ash clouds contain sulfur gases and heated particles which, when mixed with moisture, will become volcanic acid rain. Skin contact with volcanic acid rain must be avoided, as volcanic ash is classified as a respiratory hazard. Its high heat further classifies it as a physical hazard as the highly heated particles will burn on contact; therefore inhalation and physical contact with the material must be avoided.
Evacuation for fast moving toxic clouds need not be ordered in every case, as high wind speed will degrade or dissipate the cloud, making evacuation necessary only under extreme conditions.
One of the most effective methods employed for toxic cloud residential protection is a method called “Evacuation in Place”. This process requires residents to remain indoors; closing and sealing all windows and doors; and placing dripping wet towels against all visible openings, or the window flaps displayed in some wooden doors and windows.
This wet towel acts as a further barrier against wind driven particles, both trapping and reducing any contact with the material. Most toxic clouds on contact with a wet surface will change in molecular structure and become droplets; a type of moisture which will be trapped by the wet towel.
There has been very low mortality rates recorded for this type of response. Fatalities recorded using this method, were attributed to persons who were disabled and could not physically seal their homes, or were hearing and visually impaired.
In other cases, persons were completely bed ridden and isolated from regular social community contact. In other cases, authorities were not even aware of their existence.
Will atmospheric conditions worsen the situation?
Wind direction, wind speed, rainfall and time of day are the most critical atmospheric factors that must be considered when one responds to a toxic cloud hazard. Wind speed and direction can be positive factors in some scenarios; in others, it may worsen the situation.
Daytime environmental conditions, which include heat from the sun, and wind speed, may also be positive factors when planning a response. Additionally, at home residential numbers are significantly lower due to schools and workforce location patterns.
Nighttime conditions may, in the majority of scenarios, worsen toxic cloud physical impact conditions. Nights are cooler, wind speeds are slower, moisture levels are higher, and the at home population is greater.
Day and nighttime plume modelling; which is a methodology used for determining toxic cloud size and projected direction based on atmospheric and environmental conditions, drastically differ between the two time periods.
Is the appropriate personnel protective equipment available to responders that will safely allow them to enter a toxic environment to save a life?
The simple answer is yes. All fire departments worldwide carry suitably certified personal protective equipment for their personnel. Any designated, fully trained experienced HAZMAT team must be equipped with high quality personal protective equipment. Without this, experience and equipment, HAZMAT teams, regardless of their training certification will be vulnerable in all conditions.
My professional and personal association with the Barbados Fire Service tells me that they are equipped with all of the required protective equipment to permit an effective safe entry. Members of that department have also been specially trained and certified to function safely in any of these conditions.
Should responders enter a toxic environment to save a life?
Unless you are in the military and there is a declared war, or you are in law enforcement, it is almost legally impossible to order any person into a potentially life-threatening hazardous environment. This is a personal choice; and I speak only for myself, personally and professionally as a trained hazardous materials technician level responder of more than 15 years, I am prepared to enter any toxic environment, if that action will help save a life.
Mandatory certified training for technician level hazmat responders include certified competencies in biohazard and radioactive environments, to include weapons of mass destruction, and competencies in solids, liquids, gases and explosives. Certified Operations Level hazmat responders, though appropriately trained with similar competencies, can enter toxic environments, but are not expected to do so, unless it is necessary.
The managerial decision to send personnel into a toxic cloud environment to rescue or warn residents must be considered under the following:
* Are the responders trained and experienced to requisite competencies?
* Are the responders in possession of the required personal protective and gear?
* Is there a departmental policy in place that addresses this type of response?
If the answers to these questions of operational policy are yes, and personnel volunteer to enter, then there is no reason why this action should not be done.
In conversations with responders, they have all said that with the appropriate equipment, they see it as a personal duty to enter any environment where a life can be saved. The choice to enter will always be a personal one; consider this view of personal choice the next time you see a lifeguard on the beach.
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