MICROPARTICLE CONCENTRATION MEASUREMENT METHOD AND MEASUREMENT INSTRUMENT

PROBLEM TO BE SOLVED: To provide a microparticle concentration measurement method and measurement instrument which is not affected with an ambient environment and stabilizes measurement accuracy.SOLUTION: The microparticle concentration measurement method includes the steps of: irradiating a space with light to acquire scattering light from microparticles as a moving image; generating a time difference processed image resulting from difference processing of two images at different times in the moving image; subjecting the time difference processed image to binarization processing to generate a binarized image with the microparticles as white speckles; extracting a feature quantity relating to a concentration of the microparticles on the basis of the binarized image; and calculating the concentration of microparticles on the basis of the extracted feature quantity.