Improvement of emission factors

In the following Sections, measurements conducted to improve and validate emission factors as well as modelling work are described. The aim of this work was to lead to an improvement of emission factors and thus to an overall improvement of the accuracy of emission data and to quantify and reduce uncertainties. The pollutants covered include anthropogenic and biogenic precursors of ozone, primary and secondary aerosols and acidifying substances. As methods for the quantification of emissions and for developing emission inventories for CO, SO2 and NOx are more advanced and the resultant uncertainties in their emission estimates are lower than those for VOC, PM and NH3, the following Sections focus on the latter pollutants.