Determining the ideal safe haven duration in stand-alone mode is an often contested discussion. It poses more questions than answers without concise agreement by governments and industry bodies worldwide.
Safe haven or refuge chamber duration should be determined on a risk-based approach. Every chemical plant, manufacturing facility, or processing centre is different and should be assessed based on its unique conditions and the overall emergency response plan.
Safe Haven Duration in Stand-Alone Mode
A chamber’s ‘stand-alone’ duration needs to consider the resources available; at the very least it must factor in escape routes, equipment, as well as the skills and capabilities of Emergency Response Teams (ERT).
Stand-alone mode occurs when the safe haven is cut from external air and power sources, resulting in using a finite source of battery backup and breathable air. A chamber, while connected to mains power and mine air, can continue to sustain life indefinitely. However, in these instances, the supply of food and water becomes more pressing.
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Survivability in a chemical safe haven focuses on meeting fundamental requirements to sustain life, including maintaining a respirable atmosphere, and habitable environment, as well as the provision of basic needs such as water.
Petrochemical and processing safety industries are high-risk businesses. There is a careful balance between emergency preparedness and personnel protection against the costs of over insurance. Each emergency is a unique event, and it is impossible to predict with exactness, the period required to sustain personnel before rescue.
Determining Safe Haven Duration
Safe Haven and Shelter-in-Place Duration for the Petrochemical Industry can range from 4 – 12 hours.
Common hazards which can cause the use of an above-ground or shelter-in-place within the petrochemical, refining and power generation industries include fires, explosions and hazardous gases.
There is currently no minimum standard for the petrochemical industry.
In the United States, many companies utilise the American Petroleum Institute (API) Recommended Practice 753. These guidelines outline requirements for process plant portable buildings to reduce personnel risk from explosions, fire and toxic release. Considerations include shelter-in-place design, placement, and the overall emergency response plan for portable buildings located in areas where a toxic release can reach ERPG-3 levels.
Additional principles referenced are the Emergency Response Planning Guidelines (ERPGs) developed by the American Industrial Hygiene Association (AIHA).
Petrochemical Emergency Response Planning Guidelines (ERPGs)
The ERPG Handbook is used as a tool to assess and design adequate emergency response plans in a chemical release event. The values focus on a release period of 60-minutes, at varied chemical toxicity levels. However, a minimum of two to four hours is commonly requested by industry personnel.
ERPGs are air concentration guidelines for single exposures to agents. They are used as tools to assess the adequacy of accident prevention and emergency response plans, including transportation emergency planning, community emergency response plans, and incident prevention and mitigation.
Unfortunately, ERPG-1 is the most commonly used guide – yet it is not a safety standard for the industry. ERPG-1 suggests a low hazard level; individuals exposed to the maximum airborne concentration of a chemical release, over the hour period, would experience only mild, short-term health effects.
It is advised ERPG-3 be utilised as a minimum standard for emergency shelters until an industry standard is established.
Due to the nature of the industry, toxic concentration and exposure present a much higher risk. For higher-risk environments, the exposure to toxicity levels for an individual less than, or equal to, one hour are equal to the ERPG-3 concentration. Subsequently, as the exposure produces the same toxicity dose, the health effects would also be the same.
Current Safe Haven Legislation
There is currently no minimum standard for the petrochemical industry.
American Industrial Hygiene Association (AIHA), 2018, Emergency Response Planning Guidelines (ERPGs)
“…Emergency Response Planning Guidelines (ERPGs®) are values developed by the AIHA® Guideline Foundation’s Emergency Response Planning (ERP) Committee to assist emergency response personnel in planning for accidental or intentional catastrophic chemical releases to the community. ERPGs® are developed to meet the need for community emergency exposure planning guidelines, particularly for chemicals that have high potential for uncontrolled releases and those that might pose particular hazards because of their volatility and toxicity.…
ERPG–1: The maximum airborne concentration below which nearly all individuals could be exposed for up to 1 hour without experiencing more than mild, transient adverse health effects or without perceiving a clearly defined objectionable odor.
ERPG–2: The maximum airborne concentration below which nearly all individuals could be exposed for up to 1 hour without experiencing or developing irreversible or other serious health effects or symptoms that could impair an individual’s ability to take protective action.
ERPG–3: The maximum airborne concentration below which nearly all individuals could be exposed for up to 1 hour without experiencing or developing life-threatening health effects.”
American Petroleum Institute (API), 2007, Recommended Practice 753: Management of Hazards Associated With Location of Process Plant Portable Buildings
In addition to explosion and fire hazard guidance, considerations for toxic release hazards should be taken. Portable buildings located in areas where a toxic release can reach ERPG-3 levels should meet either of the following:
- Be designed for shelter-in-place, or have an emergency response plan that includes the following:
- Evacuation plan that directs personnel to a designated “shelter-in-place” or specified assembly area
- Plan to account for occupants
- Personal protection equipment (PPE) to be used by all occupants during the evacuation if required.
- Portable buildings used for Shelter-In-Place should have the following features at a minimum:
- Heating, ventilation and air conditioning systems (HVAC) capable of rapid shutdown of the system or placement in recirculation mode, whichever is more appropriate. This HVAC shutdown response should be included in the emergency response plan;
- Exhaust fans and duct penetrations of exterior surfaces equipped with a positive seal against infiltration of outside air;
- Emergency communications equipment;
- PPE to be used by all occupants during the evacuation as necessary;
- Seals for windows and doors that are present.
- American Industrial Hygiene Association (AIHA), 2018, Emergency Response Planning Guidelines (ERPGs) https://www.aiha.org/get-involved/AIHAGuidelineFoundation/EmergencyResponsePlanningGuidelines/Pages/default.aspx
- American Petroleum Institute Energy, 2018, ‘Recommended Practice 753 1st Edition June 2007’ https://www.api.org/oil-and-natural-gas/health-and-safety/refinery-and-plant-safety/process-safety/process-safety-standards/rp-753