We propose to develop a highly sensitive and compact device to monitor light absorption from atmospheric aerosols simultaneously at three spectral regions, red, green, and blue. The proposed method is primarily based on the differential photoacoustic (DPAS) technique and will also take advantage of the current rapid development on high-power semiconductor lasers. The proposed RGB DPAS Aerosol Absorption Monitor will eventually be less than 25 pounds in weight and consume approximately 300W electrical power. It will also be capable of being remotely controlled and being operated at a variety of sampling pressure conditions for the airborne measurements. Since all the major components of the proposed system are commercially available except the home-designed acoustic cells, its total manufacturing cost could be less than $20,000 per unit.