LCT50 FormulationLCT50 Formulation

1. Purpose

2. History

3. Philosophy: CATO vs. NTOA

4. Formula and Calculations

5. Practical Applications

6. Tactical Case Study

LCT50 Course Overview

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 Purpose

“Concentration (LC50) multiplied by the time (T) of exposure that is lethal to 50% of exposed personnel.”

(Usually expressed in minutes of exposure.)

LCT50 Defined

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 History

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 Philosophy

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

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 (CV)

Constant (.71) • Based on US Army research. • Research that was based on how much agent would kill a human.• Will never change.

LCT50 Formula (Constant)

1. _______ x _______ x _______ = ___________

Length Width Height Cubic Feet

2. _________ x CV = _________________

Cubic Feet Total Grams Needed

3. __________ ________ x .71 = _____________

Cubic Feet Total # of LCT50 (minutes)

Grams

LCT50 Worksheet (part 1)

1. _______ x _______ x _______ = ___________

Length Width Height Cubic Feet

2. _________ x .71 _______________ = ________________

Cubic Feet Proposed LCT50 Grams of Agent

LCT50 Worksheet (part 2)Proposed LCT50 - Time

1. _______ x _______ x _______ = ___________

Length Width Height Cubic Feet

2. __________ ______________ x .71 = _______________ Cubic Feet Grams of Agent LCT50 (minutes)

LCT50 Worksheet (part 2)Amount of Agent Used

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!

LCT50 Munitions Needed

Munition Data Cards

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