LCT50 Formulation
LCT50 Course Overview
1.
2.
3.
4.
5.
6.
Purpose
History
Philosophy: CATO vs. NTOA
Formula and Calculations
Practical Applications
Tactical Case Study
LCT50 Purpose
1. Helps determine amount of
chemical agent to use.
2. Estimates the time a suspect can
remain in agent environment.
3. Provides a guideline for command
staff and for potential criminal &
civil litigation.
LCT50 Defined
“Concentration (LC50) multiplied
by the time (T) of exposure that
is lethal to 50% of exposed
personnel.”
(Usually expressed in minutes of exposure.)
LCT50 History
 Formula developed from an Edgewood Arsenal study
of CS exposure in 1967.
• Edgewood Arsenal is a chemical research facility (now
known as US Army Medical Research Institute of
Chemical Defense).
 Conducted for the U.S Army who was replacing CN
with CS for outside riot control. Not inside or for civil
law enforcement!
 Conducted in a static, sealed container.
 Formula values determined concentration levels were
lethal for 50% of population.
LCT50 Philosophy
 National Tactical Officer’s Association
 California Association of Tactical Officers
LCT50 Philosophy
NTOA
 Based on use of force “reasonableness” standard
(Graham vs. Connor).
 Don’t need a formula to use other forms of force.
 LCT50 based on faulted research:
 No consideration given to biological/metabolic differences.
 Conducted in static sealed containers.
 CS was intended for outside riot control, not inside sealed
environments.
LCT50 Philosophy
CATO

Formula and incident based.
 Uses Edgewood Arsenal Study as a “baseline.”
 Bases concentration variable (i.e. .004, .008, etc) on
tactical situation.
 Estimates the time a suspect can remain in the agent.
LCT50 Formula
3-Step Process
1.
Compute room(s) volume ( L x W x H )
Equals = CUBIC FEET
2.
CUBIC FEET X CONCENTRATION VARIABLE
Equals = GRAMS of AGENT NEEDED
3.
CUBIC FEET
GRAMS of AGENT NEEDED
X .71 (CS Constant) = LCT50 in minutes
LCT50 Formula (CV)
Concentration Variable
• Equates to grams of agent per 1000 cubic feet.
• US Department of Energy research determined 4 grams per 1000 cubic
feet ( or .004) as the smallest concentration to yield agent symptoms.
• A higher variable will give a higher concentration of agent, but a shorter
LCT50.
• A lower variable will yield a lower agent concentration, but a higher LCT50.
• For Example:
– .012 = 60 minutes
– .008 = 89 minutes
– .004 = 178 minutes
• Concentration variables should be based on SWAT chemical agent
deployment philosophy.
LCT50 Formula (Constant)
Constant (.71)
• Based on US Army research.
• Research that was based on how much agent would kill a human.
• Will never change.
LCT50 Worksheet (part 1)
1. _______ x _______ x _______ = ___________
Length
Width
Height
Cubic Feet
2. _________ x CV = _________________
Cubic Feet
Total Grams Needed
3. __________
Cubic Feet
________ x .71 = _____________
Total # of
LCT50 (minutes)
Grams
LCT50 Worksheet (part 2)
Proposed LCT50 - Time
1. _______ x _______ x _______ = ___________
Length
Width
Height
Cubic Feet
2. _________ x .71
Cubic Feet
_______________ = ________________
Proposed LCT50
Grams of Agent
LCT50 Worksheet (part 2)
Amount of Agent Used
1. _______ x _______ x _______ = ___________
Length
Width
Height
Cubic Feet
2. __________
Cubic Feet
______________ x .71 = _______________
Grams of Agent
LCT50 (minutes)
LCT50 Munitions Needed
Now that we know the “total # of grams of
agent” and our LCT50, how many munitions
will we need?
ANSWER:
Divide total # of grams of agent by the
amount of agent in your munition of choice.
This is where a munitions data card comes
in handy!
Munition Data Cards
Questions
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