An external mix air assisted spray nozzle assembly having a nozzle body, and an air cap for a directing pressurized air streams on a discharging liquid stream external to the liquid discharge orifice of the nozzle assembly for atomizing and forming the liquid into the desired spray pattern. The air cap includes an upstream internal air chamber, an external, downstream liquid discharge and mixing chamber, and a central opening coaxial with the liquid discharge orifice communicating between the upstream and downstream chambers. The air cap further includes a plurality of angled pressurized air discharge passages which communicate with an annular plenum of the air chamber disposed in surrounding relation to the central opening for enabling substantially uniform particle breakdown and distribution at lower air pressures than heretofore possible.