The problem of small particle size detection is important for industrial and environmental applications. Previous investigations have shown the possibility of using the laser breakdown method to achieve this goal; the sensitivity of this method is a thousand times higher than that of conventional methods. However, for small particle sizes, the damage threshold of the solid target in this case is very close to the breakdown point of pure air. After breakdown, there is a small volume of dense hot plasma that emits radiation. We analyzed this radiation using an analytical model and simulation code as well as by experiment, and found that the emission intensity varied depending on the laser type and plasma parameters including initial particle size.