The 11-level GFDL global chemical transport model has been used to assess the impact of fossil fuel combustion emissions on the distribution of reactive nitrogen compounds (NOy) in the troposphere. We conclude that 1) the model reproduces the observed spatial patterns of wet deposition near the major fossil fuel combustion source regions; 2) the fossil fuel source accounts for a large fraction of the observed surface concentrations and wet deposition fluxes of HNO3 in the extra tropical North Atlantic; 3) it appears that a significant fraction of NOy observed in the marine free troposphere in the eastern North Pacific cannot be explained in terms of the fossil fuel source; 4) at the more remote Mauna Loa, Hawaii site, less than 30% of the observed NOy during May 1988, appears to be due to distant fossil fuel sources; 5) even with the explicit treatment of PAN as a transported species, the fossil fuel source has only a minor impact on NOy levels in the remote tropics and in the Southern Hemisphere; 6) the relatively high levels of NOy observed over western Alaska during the ABLE 3A experiment in July-August 1988, cannot be explained in terms of long-range transport of fossil fuel combustion emissions; 7) away from source regions, PAN is a major component of fossil fuel NOy. -from Authors