TAB G - Why the MM-1 is Not a Suitable Warning Device Using the Air/Hi Method of the Air Monitor Operating Mode

In the Air/Hi method, the MM-1 can detect chemical warfare agent vapors, but according to US Army experts, it is not optimized for this purpose. In fact, the MM-1 is approximately 500 times less sensitive to nerve agent vapors than the M43A1.[319] In 1988 MM-1 tests, the US Army found that it took a high concentration of sarin (62 mg/m3) to cause the MM-1 to indicate chemical warfare agent presence while operating in this method.[320] In 1994, the Defense Science Board Task Force Report on Persian Gulf War Health Effects stated, "when operating in the air sampling mode, the FOX is not a suitable warning device; very high concentrations of chemical agents would have to be present, such that unprotected troops in the vicinity would be adversely and acutely affected."[321] A table in the Board’s report[322] illustrates this point by showing detector characteristics for nerve agents in vapor form; data from that table is shown in Table 3.

Table 3. Vapor nerve agent detector characteristics



(vapor concentration)

Response Time

M256A1 Kit G-series 0.005 mg/m3 15 min
M43A1 Vapor detector G-series 0.1-0.2 mg/m3 <=2 min
Chemical Agent Monitor GB [sarin] <= 0.1 mg/m3 <=1 min
Mobile mass spectrometer GB [sarin] 62 mg/m3 <=45 sec

The "sensitivity" column of Table 3 lists each detector’s sensitivity to G-series nerve agents such as sarin. This sensitivity is the minimum amount of nerve agent vapor required for the equipment to detect nerve agent presence. These minimum amounts, or concentrations, can be used to calculate whether the vapor would physically affect unprotected, exposed people. Concentration is expressed as milligrams per cubic meter of air (mg/m3). The effect a nerve agent vapor has on a person depends on the cumulative dose received through breathing or absorption.[323] The term dosage represents a cumulative exposure over a period of time and is calculated by multiplying the amount of nerve agent present by the time of exposure (mg•min/m3).[324]

At specific dosages, specific physical symptoms are expected. Studies conducted by the military determined specific dosages at which a person will exhibit symptoms of exposure to sarin nerve agent. At dosages of 0.5 mg•min/m3, personnel experience first noticeable physical effects, such as miosis (contraction of the pupils accompanied by pain in and behind the eyes). The earliest effects on the respiratory tract are a runny nose, tightness in the chest, and occasionally, prolonged wheezing.[325] The larger the dose, the more severe the effects. According to the toxicity data for sarin, a dosage of 35 mg•min/m3 is lethal to 50 percent of exposed, unprotected people.[326]

Based on the concentration required to be present (noted by the Army and the Defense Science Board) for the MM-1 to indicate sarin presence (62 mg/m3), the following dosages can be calculated for such an environment.

Table 4 summarizes the effects on personnel at these dosages.

Table 4. Calculated dosages and their effects (sarin vapor concentration of 62 mg/m3)

Exposure Time



Effects on personnel[328]

1 second

1.03 mg•min/m3

First Noticeable Effects
(reached at 0.5 mg•min/m3)

Exposed personnel manifest physical symptoms of nerve agent exposure

10 seconds

10.3 mg•min/m3

20 times the First Noticeable Effects dosage

Exposed personnel manifest more severe physical symptoms of nerve agent exposure

35 seconds

36 mg•min/m3

Median Lethal Dosage (reached at 35 mg•min/m3)

50% of unprotected, exposed personnel are fatalities

Another example shows that although an MM-1 would not indicate the presence of sarin vapor, a specific amount of sarin vapor would still be harmful to unprotected, exposed people. In an environment in which 35 mg/m3 sarin is present, the MM-1 would not indicate the presence of sarin, yet after 1 minute in this environment, unprotected, exposed people would have received a dosage of 35 mg•min/m3, exceeding the dosage that causes fatalities to half of unprotected, exposed people.

These examples support the conclusion that "the FOX is not a suitable warning device; very high concentrations of chemical agents would have to be present, such that unprotected troops in the vicinity would be adversely and acutely affected."[329] This means that battlefield casualties and fatalities to unprotected, exposed personnel would occur before the MM-1 could detect sarin. The Army MM-1 test and evaluation report made this point more concisely; "The MM-1 does not detect chemical warfare agent vapor at the danger level to humans."[330]


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