# Presentation: 154980

## WHAT IS AN ACCIDENT

**WHAT IS AN ACCIDENT**

## OBJECTIVE

- CA58

- Identify types of potential chemical accidents and associated hazards

## Can be defined in several ways
an unplanned release of chemical warfare agent into environment at levels which exceed those permitted by state or federal regulations
more conservative definition is any unplanned event that could lead to the release of chemical warfare agent

- Can be defined in several ways
- an unplanned release of chemical warfare agent into environment at levels which exceed those permitted by state or federal regulations
- more conservative definition is any unplanned event that could lead to the release of chemical warfare agent

**AN ACCIDENT . . .**

## Important to know amount of material accidentally released
Amount of material released called  “source term”
Source term and weather conditions at time of release determine
how far downwind hazardous materials will travel
concentration of chemical warfare agent to which people could be exposed

- Amount of material released called  “source term”
- Source term and weather conditions at time of release determine
- how far downwind hazardous materials will travel
- concentration of chemical warfare agent to which people could be exposed

- CA60

**SIZE OF ACCIDENT**

## PROXIMITY TO POTENTIAL ACCIDENT SITE

**PROXIMITY TO POTENTIAL ****ACCIDENT SITE**

- Also important to know how close people might be to a potential accident site and their location with respect to airborne agent plume

- Illustrated CSEPP installation and community

## ACCIDENT LIKELIHOOD

**ACCIDENT LIKELIHOOD**

- Most likely accidents are small ones that do not pose a threat except to someone in very close proximity to accident
- Large accidents (source terms large enough to pose a threat to community) have much lower probability of occurring
- Unlikely that an accident will cause injury or death to anyone

## Engineers and scientists systematically studied different ways accidents could occur and estimated how likely events were that caused an accident
They estimated probabilities of many different accidents and calculated number of fatalities that could occur for each accident
They calculated the consequences of each accident

- They estimated probabilities of many different accidents and calculated number of fatalities that could occur for each accident
- They calculated the consequences of each accident

- CA63

**WHAT IS MEANT BY UNLIKELY?**

- Calculation of risk

## POTENTIAL ACCIDENT TYPES AND HAZARDS

**POTENTIAL ACCIDENT TYPES ****AND HAZARDS**

- If accident large enough to pose threat to public, dominant hazard is from breathing air in which agent exists as vapor
- Paths for liquid chemical warfare agent to travel from accident to off-site are limited and relatively easy to block therefore people off-site unlikely to encounter liquid agent

## THREE BASIC TYPESOF POTENTIAL ACCIDENTS

**THREE BASIC TYPES****OF POTENTIAL ACCIDENTS**

- 1.	Spill
- 2.	Explosion
- 3.	Fire

## SPILL

**SPILL**

- (not to scale)

- Onto ground or other surfaces
- Resulting puddle of agent (liquid deposition) can evaporate into vapor and drift downwind

- Example of a plume resulting from a spill

## EXPLOSION

- (not to scale)

**EXPLOSION**

- Causes droplets of agent to be formed
- Larger, heavier droplets quickly fall to ground (deposition)
- Releases vapors and aerosols (smaller droplets and particles) that can travel greater distances

- Example of a plume resulting from an explosion

## FIRE

**FIRE**

- (not to scale)

- Both aerosols and vapors are formed
- Vapors and aerosols lifted higher into air because of heat from fire
- Hazard similar to those of an explosion

- Example of a plume resulting from a fire

## DIFFERENCE BETWEENAEROSOLS AND VAPORS

- CA69

**DIFFERENCE BETWEEN****AEROSOLS AND VAPORS**

- Think of a chemical agent release in terms of hair spray coming from a spray can:
- when spray is release, it is an aerosol
- larger particles and/or droplets are deposited near point of release
- particles quickly fall out of air onto hair and skin
- person across room can smell hair spray from breathing vapors released

## It is very unlikely the public would be exposed to droplets and aerosols
Particles will mostly fall out of plume (via deposition) by time plume reaches installation boundary

- It is very unlikely the public would be exposed to droplets and aerosols
- Particles will mostly fall out of plume (via deposition) by time plume reaches installation boundary

**WHAT IF AN ACCIDENT OCCURS?**

## VAPOR HAZARD

**VAPOR HAZARD**

- For most accidents, the primary health hazard comes from vapors when they are breathed in or come in contact with skin or eyes
- Agent vapors pose greatest hazard when inhaled because they are rapidly absorbed by lung tissues
- Lethal dosage for agent vapor breathed in is several times lower than lethal dosage for vapor contact with skin

## ACCIDENT CATEGORIES

- Selection of protective action strategies contingent on characteristics of accident
- Accident categories are group of accident scenarios bound together by common source terms and meteorological conditions
- Designed to support grouping of large number of protective action strategies
- Each installation has set of accident categories

- CA72

## CHEMICAL EVENT EMERGENCYNOTIFICATION SYSTEM

- Standard chemical accident notification
- Provides a common language between installation and off-site emergency responders
- Fosters clear understanding and ready reference for emergency response actions
- Off-site response consists of 4 levels
- nonsurety (does not involve chemical warfare agents)
- limited area, post-only, and community emergencies (involve chemical warfare agents)

- CA73

## NON-SURETY EMERGENCY

**NON-SURETY EMERGENCY**

- General interest to public
- Poses no chemical surety hazard
- Action: Notification to IRZ designated points of contact

- CA74

- Illustrated CSEPP installation and community

- Army Installation Boundary

- Limited
- Area
- Boundary

## LIMITED AREA EMERGENCY

- Illustrated CSEPP installation and community

- Plume

- Army Installation Boundary

- Limited
- Area
- Boundary

**LIMITED AREA EMERGENCY**

- Declared when predicted chemical agent no-effects dosage does not extend beyond chemical limited area
- Action: Notification of IRZ and State points-of-contact
- IRZ emergency response officials may go to level of readiness

## POST-ONLY EMERGENCY

- CA76

- Declared when predicted chemical agent no-effects dosage extends beyond chemical limited boundary but not installation boundary
- Not expected to present danger to off-site public
- Action: Notification of IRZ, PAZ, and State-designated points-of-contact
- IRZ response organizations mobilize
- precautionary protective actions may be initiated in nearby areas

- Illustrated CSEPP installation and community

- Plume

- Army Installation Boundary

- Limited
- Area
- Boundary

## COMMUNITY EMERGENCY

- Declared when predicted chemical agent no-effects dosage extends beyond installation boundary
- Action: Notification of IRZ, PAZ, and State-designated points-of-contact
- all emergency responseorganizations mobilize
- IRZ and affected PAZ areasimplement specified protective actions

- CA77

- Illustrated CSEPP installation and community

- Plume

- Army Installation Boundary

- Limited
- Area
- Boundary

## Army’s detection capability consists of low-level and gross-level detectors
Any vapor detection efforts off-site would be conducted by Army survey teams using appropriate equipment

- Any vapor detection efforts off-site would be conducted by Army survey teams using appropriate equipment

- CA78

**CHEMICAL WARFARE****AGENT DETECTION**