The effects of dust on 1.06‐&mgr;m laser‐induced air breakdown for 100‐nsec pulses are reported. The thresholds in clean air were measured as a function of spot size and were found to scale as &lgr;−2compared to the 10.6‐&mgr;m results. A single 50‐&mgr;m carbon particle present in the beam lowered the threshold to ≃5×109W/cm2—a factor of approximately 0.02 that of clean air. The fractional reduction in threshold due to dust particles was comparable to that reported for 10.6‐&mgr;m breakdown.