A dual-wavelength, diode-seeded, flash-lamp-pumped Ti:sapphire laser system has been developed. Injection seeding allowed the attainment of high output energies (130 mJ), narrow linewidth (250 MHz), and high reliability. Furthermore, an original method is presented for dual-wavelength operation, using diode current sweeping. These specifications are ideal for differential absorption lidar applications, and the example of NO(2) detection is presented. Extension to other pollutants is discussed.