Air negative ion concentration meter attracts air (or gas with ions) to count the concentration of positive and negative ions (gas) in the air through charged parallel polarized electrode plates, and the outer two plates keep polarized (positive and negative) potentials. In the middle is a linear detector plate. The pore of air is 4MM, and the potential of polarization region is 1000V/M.. It can measure both positive and negative ions. It can also measure the concentration of negative ions related to the body, such as environment, solid matter (stone and ash), cloth, fiber, etc.