The dust sensor module DSM501A is low cost, compact size for a particle density sensor.it is used to quantitative particle (> 1 micron) measurement with the principle of particle counter, can sense the tobacco smoke and pollen, house dust .     This sensor is consist of light emitting diode lamp, detector, signal amplifier circuit and heater, it can be used in applications such as the air cleaner or air purifier, users can used this sensor easily with sensor PWM output.