In the Air/Hi method of the air monitor operating mode, the MM-1 can detect chemical warfare agent vapors. However, 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.^[314] 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.^[315] 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."^[316] A table in the Board’s report^[317] illustrates this point by showing detector characteristics for nerve agents in vapor form; data from that table is shown in Table 3.

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. 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).^[318]

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. 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.^[319]

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.

• To obtain the dosage for one second in an environment with 62mg/m³, divide the concentration (62 mg/m³) by 1 minute (60 seconds), which results in a per/second dosage of 1.03 milligram minutes per cubic meter of air (1.03 mg•min/m³). Since this is more than double the dosage that would yield first noticeable effects, it is probable that some unprotected personnel (e.g., those in the Marine breaching lanes) would show first noticeable effects.
• Continued exposure for 10 seconds in this environment (multiply the per/second dosage of 1.03 mg•min/m³ by 10, which yields 10.3 mg•min/m³) would result in unprotected personnel showing more severe effects.
• Similarly, an exposure time of 35 seconds results in a dosage of 36 mg•min/m³, which exceeds the dosage that causes fatalities to half of unprotected personnel.

Table 4 summarizes the effects on personnel at these dosages.

The data in Table 4 shows that although an MM-1 would not indicate the presence of sarin vapor, if a certain amount of sarin vapor was present, it would still be harmful to unprotected, exposed people. For example, in an environment in which 35 mg/m³ sarin is present, the MM-1 would not indicate the presence of sarin, yet after 35 seconds in this environment; unprotected, exposed people would have received a dosage of over 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."^[322] 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."^[323]

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