An apparatus and method for verifying the temperature compensation correction factor accuracy of an electrometer is provided. The electrometer includes an electrical amplifier to convert a current signal to a voltage signal. The electrometer also includes a compensation circuit to modify the voltage signal for temperature compensation. The electrometer further includes a heat producing device to induce a temperature change of the electrical amplifier and the compensation circuit. An environmental radiation monitor is also provided. The environmental radiation monitor includes a power supply, a high pressure ionization chamber, and the electrometer. The method includes providing an environmental radiation monitor, measuring the voltage signal at a first time, activating a heat producing device, measuring the voltage signal at a second time, and comparing the two measured values of the voltage signal.