This chapter reports on recent work by EFTEC for the UK Department of the Environment to refine damage estimates for emissions of nitrogen dioxide (NO) across UN IECE (EFTEC, 1996). NO emissions are partially responsible for concentrations of both ozone (03) and small particulate matter, which in turn are associated with adverse impacts on human health. The work was able to draw on several new sources of information in addition to those mentioned in earlier chapters, notably a recent epidemiological study across Europe examining the impact of air pollution on human health, and developments in the atmospheric modelling of ozone formation (APHEA, 1996). Some methodological improvements have also been included, in an attempt to deal with the difficult issue of uncertainty in the final damage estimates. The scope of the damage estimates is still quite small - the estimates presented only reflect damage to human health and buildings damage. Possible damage to flora and fauna, wildlife, crop production and buildings of special cultural interest are not reflected in the final estimates. It may well be worthwhile cutting emissions of NOx on the basis of these omissions alone.