Air pollution by nitrogen oxides in The Netherlands

The Netherlands have the highest energy consumption per unit area in the world and consequently will have one of the highest emission densities of nitrogen oxides. With íncreasing energy demand the air pollutíon aspects related to NOx, became so important that research on these aspects was considered necessary. At the end of the sixties various Dutch organizations began studies in the NOx-field. This paper reports about three of these studies. Firstly the activities in the field of measuring ground level concentrations of NOx, and
related products are described. In The Netherlands a tendency to higher ozone concentrations has been noted. However, these increased ozone concentrations during smog periods proved to occur simultaneously in large areas and can, as such, not directly be related to the emissions ol large industrialized and urbanized areas in The Netherlands. The second part deals with f ield measurements of the NOx-emission of chiefly industrial installations, firing Groningen natural gas. Contrary to what had been expected originally, gas-fired installations proved to emit rather low amounts of Nox. It was found that for gas-fired, installations, varying from hot-water production uniti in the domestic field to industrial installatíons with a heat input up to 100 MW, the emissionis rather constant, amounting to about 50 g NOx (calculated as NO2) per l0" Joule. Larger installations can produce considerably higher amounts of NOx. On the basis of available data an emission
inventory for The Netherlands is given. The influence of the main parameters of large boilers on NOx-formation has been studied and discussed. and possibilities to decrease NOx-emission from gas-fired large boilers are
described in the last part of the paper.