The NEC directive, an EU directive laying down emission ceilings for a range of air pollutants for all member states, is about to be amended. This report describes the results of a social cost-benefit analysis (SCBA) of possible new NEC targets for 2020, making due allowance for the impact of an intensification of Dutch climate policy on emissions of NEC pollutants. Policies already scheduled for implementation were included in a �zero variant�. The study is to serve as part of the input for establishing the Dutch position in negotiations within the EU on the level of the emission ceilings. The net present value of all impacts to which a price was assigned amounts to around minus 1.7 billion Euro. In the �project variant� the net present value of the external effects was calculated as 5.2 billion Euro (with benefits to nature being taken along as an as yet unvalued item). The main factor on the benefit side was reduced mortality due to exposure to airborne particulates. This involves both primary and secondary particles, implying that these benefits also depend on cuts in NH3, NOx and SO2 emissions. Chronic bronchitis and days of illness (hours/days lost at work) due to exposure to particulates also play a significant role in the SCBA. The other effects contribute only marginally to the analysis results. A comparison of the discounted costs with the benefits shows that a tightening of NEC targets is an efficient form of policy, with the benefits of 3.5 billion Euro clearly well in excess of the costs. This conclusion remains valid even if a lower value (than is customary) is assigned to the health effects of improved air quality. The benefits will be even greater (their monetary value will be even more positive) if impacts on nature and ecosystems are also included in the equation. In a tentative analysis we show that in this study benefits to nature may amount to as much as 20% of the health benefits. The costs of tightening the NEC targets are borne by the various sectors, but appear to be affordable to society as a whole. Ultimately, most of the costs will be passed on to private citizens. The benefits of the NEC targets accrue to all citizens benefiting from cleaner air. In the Netherlands the benefits arise largely through measures to concurrently reduce the NH3 and primary particulate emissions of Dutch agriculture and measures taken in neighbouring countries to cut particulate emissions.