ABSTRACT
This chapter presents an integrated view of nitrogen oxides (NOx)and related nitrogen compounds, beginning with an overview of the effects associated with nitrogen. It outlines past and projected trends in nitrogen oxide emissions, taking into account the provisions of the Clean Air Act Amendments of 1990. The chapter summarizes some of the key uncertainties that limit our ability to conduct an integrated assessment of cumulative risk and to develop alternative strategies for reducing those risks. Ozone and other photochemical oxidants form in the troposphere through reactions of nitrogen oxides and volatile organic compounds in the presence of sunlight and high temperature. NOx is transformed into nitric acid vapor or aerosol, depending on atmospheric conditions. Atmospheric nitrogen oxides, or more broadly, nitrogen compounds, play a role in most or all of the major air pollution problems we face.
