Recent trends and projections of primary NO2 emissions in Europe

Abstract An assessment of recent trends in primary NO 2 emissions has been carried out for ten case study locations across the European Union. Estimates of the percentage of NO x from road traffic emitted as primary NO 2 (f-NO 2 ) have been derived for 1995, 2000 and 2005 by combining the results of a literature survey of primary NO 2 emission factors for different vehicle types and technologies with an emission inventory. Estimates of f-NO 2 have also been derived from ambient monitoring data at roadside sites in each case study location using a model. The results of the analysis of trends show that f-NO 2 has increased in recent years and that the rate of increase has been greatest since 2000. f-NO 2 has increased from 8.6% in 2000 to 12.4% in 2004 as an average across the monitoring sites and from an average of 6.3% in 2000 to 10.6% in 2005 as an average of the emission inventory based calculations for the case study countries. f-NO 2 is predicted to increase further to an average of 19.6% in 2010 and 32.0% in 2020 as a result of the further penetration of exhaust after treatment technologies for diesel vehicles in the fleets. This increase is expected to be offset by the large reduction in NO x emissions over this period, resulting in an increase in NO 2 emissions from road traffic to 2015, followed by a decline to close to 2004 levels by 2020. Estimates of future ambient NO 2 concentrations have also been calculated for the roadside monitoring sites included in the study. At 29 out of 45 of these sites the annual mean NO 2 limit value is predicted to be exceeded in 2010. At 22 of these sites, the annual mean concentration is expected to remain above the limit value until 2020 and beyond.