This paper examines the air quality impact of using distributed generation (DG) to satisfy future growth in power demand in the South Coast Air Basin of Los Angeles, relative to the impact when the demand is met by expanding current central generation (CG) capacity. The impact of decreasing boiler emissions by capturing the waste heat from DGs is not examined. The air quality impacts of these two alternate scenarios are quantified in terms of hourly maximum ground-level and annually averaged primary NOx concentrations, which are estimated using AERMOD. This study focuses on the impact of primary emissions at source-receptor distances of tens of kilometers. We find that the shift to DGs has the potential for decreasing maximum hourly impacts of power generation in the vicinity of the DGs. The maximum hourly concentration is reduced from 25 to 6 ppb if DGs rather than CGs are used to generate power. However, the annually averaged concentrations are likely to be higher than for the scenario in which existing CGs are used to satisfy power demand growth. Future DG penetration will add an annual average of 0.1 ppb to the current basin average, 20 ppb, while expanding existing CGs will add 0.05 ppb. (C) 2011 Elsevier Ltd. All rights reserved.