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Cooking organic aerosol (COA) is currently not included in European emission inventories. However, recent positive matrix factorization (PMF) analyses of aerosol mass spectrometer (AMS) measurements have suggested important contributions of COA in several European cities. In this study, emissions of COA were estimated for the UK, based on hourly AMS measurements of COA made at two sites in London (a kerbside site in central London and an urban background site in a residential area close to central London) for the full calendar year of 2012 during the Clean Air for London (ClearfLo) campaign. Iteration of COA emissions estimates and subsequent evaluation and sensitivity experiments were conducted with the EMEP4UK atmospheric chemistry transport modelling system with a horizontal resolution of 5 km × 5 km. The spatial distribution of these emissions was based on workday population density derived from the 2011 census data. The estimated UK annual COA emission was 7.4 Gg per year, which is an almost 10 % addition to the officially reported UK national total anthropogenic emissions of PM2.5 (82 Gg in 2012), corresponding to 320 mg person−1 day−1 on average. Weekday and weekend diurnal variation in COA emissions were also based on the AMS measurements. Modelled concentrations of COA were then independently evaluated against AMS-derived COA measurements from another city and time period (Manchester, Jan–Feb 2007), as well as with COA estimated by a chemical mass balance model of measurements for a two-week period at the Harwell rural site (~ 80 km west of central London). The modelled annual average contribution of COA to ambient particulate matter (PM) in central London was between 1–2 μg m−3, and between 0.5–0.7 μg m−3 in other major cities in England (Manchester, Birmingham, Leeds). It was also shown that cities smaller than London can have a central hot-spot of population density of smaller area than the computational grid cell, in which case higher localised COA concentrations than modelled here may be expected. Modelled COA concentrations dropped rapidly outside of major urban areas (annual average of 0.12 μg m−3 for the Harwell location), indicating that although COA can be a notable component in urban air, it does not have a significant effect on PM concentrations on rural areas. The possibility that the AMS PMF-apportionment measurements overestimate COA concentrations by up to a factor of 2 is discussed. Since COA is a primary emission, any downward adjustments in COA emissions would lead to a proportional linear downward scaling in the absolute magnitudes of COA concentrations simulated in the model.

We present high-resolution atmospheric chemistry transport model (ACTM) simulations of secondary organic aerosol (SOA) formation over the UK for 2012. Our simulations include additional diesel-related intermediate volatility organic compound (IVOC) emissions derived directly from comprehensive field measurements at an urban background site in London during the 2012 Clean Air for London (ClearfLo) campaign. Our IVOC emissions are added proportionally to VOC emissions, as opposed to proportionally to primary organic aerosol (POA) as has been done by previous ACTM studies seeking to simulate the effects of these missing emissions. Modelled concentrations are evaluated against hourly and daily measurements of organic aerosol (OA) components derived from aerosol mass spectrometer (AMS) measurements also made during the ClearfLo campaign at three sites in the London area. Good hourly performance in comparison to the measurements was shown, giving confidence in the SOA prediction skill of the ACTM system used. According to the model simulations, diesel-related IVOCs can explain on average ~30% of the annual SOA in and around London. Furthermore, the 90-th percentile of modelled daily SOA concentrations for the whole year is 3.8 μg m−3 (more than 40% of which is produced from the missing diesel precursors), constituting a notable addition to total particulate matter. More measurements of these precursors (currently not included in official emissions inventories) is recommended. During the period of concurrent measurements, SOA concentrations at the Detling rural background location east of London were greater than at the central London location. The model shows that this was caused by an intense pollution plume with a strong gradient of imported SOA passing over the rural location. This demonstrates the value of modelling for supporting the interpretation of measurements taken at different sites or for short durations.

The reduction of ambient concentrations of fine particulate matter (PM2.5) is a key objective for air pollution control policies in the UK and elsewhere. Long-term exposure to PM2.5 has been identified as a major contributor to adverse human health effects in epidemiological studies and underpins ambient PM2.5 legislation. As a range of emission sources and atmospheric chemistry transport processes contribute to PM2.5 concentrations, atmospheric chemistry transport models are an essential tool to assess emissions control effectiveness. The EMEP4UK atmospheric chemistry transport model was used to investigate the impact of reductions in UK anthropogenic emissions of primary PM2.5, NH3, NOx, SOx or non-methane VOC on surface concentrations of PM2.5 in the UK for a recent year (2010) and for a future current legislation emission (CLE) scenario (2030). In general, the sensitivity to UK mitigation is rather small. A 30 % reduction in UK emissions of any one of the above components yields (for the 2010 simulation) a maximum reduction in PM2.5 in any given location of ∼ 0.6 µg m−3 (equivalent to ∼ 6 % of the modelled PM2.5). On average across the UK, the sensitivity of PM2.5 concentrations to a 30 % reduction in UK emissions of individual contributing components, for both the 2010 and 2030 CLE baselines, increases in the order NMVOC, NOx, SOx, NH3 and primary PM2.5; however there are strong spatial differences in the PM2.5 sensitivities across the UK. Consequently, the sensitivity of PM2.5 to individual component emissions reductions varies between area and population weighting. Reductions in NH3 have the greatest effect on area-weighted PM2.5. A full UK population weighting places greater emphasis on reductions of primary PM2.5 emissions, which is simulated to be the most effective single-component control on PM2.5 for the 2030 scenario. An important conclusion is that weighting corresponding to the average exposure indicator metric (using data from the 45 model grids containing a monitor whose measurements are used to calculate the UK AEI) further increases the emphasis on the effectiveness of primary PM2.5 emissions reductions (and of NOx emissions reductions) relative to the effectiveness of NH3 emissions reductions. Reductions in primary PM2.5 have the largest impact on the AEI in both 2010 and the 2030 CLE scenario. The summation of the modelled reductions to the UK PM2.5 AEI from 30 % reductions in UK emissions of primary PM2.5, NH3, SOx, NOx and VOC totals 1.17 and 0.82 µg m−3 for the 2010 and 2030 CLE simulations, respectively (not accounting for non-linearity).

International audience; NH3 and NOx account together for close to 90 % of the reactive nitrogen (Nr) input into the atmosphere. Emissions have been strongly increasing since preindustrial times, leading to a cascade of direct or indirect environmental impacts. While global satellite measurements of NO2 are available since two decades and have largely contributed to a better knowledge of anthropogenic pollution sources and of atmospheric transport and chemistry, this was not the case until recently for NH3. In this presentation we will shortly review the improved methodology for retrieving NH3 globally and daily from IASI observations and show first validation results. We will describe the first 6-years of global NH3 measurements from IASI and discuss the distributions with emphasis on NH3 source apportionment and the variability in concentrations on various spatial scales, both seasonal and interannual. We will further examine the complementarity of simultaneous NH3 and NO2 satellite measurements (from IASI and GOME-2), possibly complemented by those of nitric acid (HNO3), to bring additional insight into the partitioning of reactive nitrogen sources and their relations in atmospheric processes. The presentation will briefly expose current limitations in the monitoring of Nr species from satellites and perspectives for possible improvements.

Background Individual behavioural and time-activity patterns lead to substantial variations of human exposure to ambient air pollutant concentrations. As a consequence static data from observation ...

Impact Assessment (IA) intends to collect evidence on the likely impacts of new policies and thereby minimize unwanted side-effects and maximize the benefits to society. Although it is a requirement in the EC and all OECD countries, the scope and methods vary considerably. Governments have invested considerably in research to support the evidence basis of policy making for sustainable development. However, the general picture shows a gap between the proliferation of IA tools from the scientific community and their actual use in the policy process. The FP7 network of excellence LIAISE (www.liaise- noe.eu) is designed to identify the causes for non-use of IA tools and bridge the gaps between researchers with a generally strong orientation towards their (disciplinary) peers and practitioners who tend to focus on their policy domain and policy problems. LIAISE aims at: 1) understanding of the policy process and the resulting needs for IA knowledge and IA tools; 2) description of IA tools and scientific IA expertise in a standardised way; 3) a shared IA toolbox targeted at the needs of both researchers and practitioners; 4) a shared IA research agenda integrating scientific knowledge gaps and the priorities for the development of new IA knowledge that arise from the future policy agenda; and 5) safeguarding the project results beyond the period of project funding, by developing an institutional setting and a business plan that facilitate the extension of the present consortium towards a broad centre of IA expertise with a structural permanence. A lively interaction between the different communities involved, is essential to realize these objectives. The Berlin Conference is an important opportunity to inform external research groups about the LIAISE approach to bridging the gap between science and policy. Their feedback and views on possible next steps in the further integration of the IA research community are highly valued, as well as their interest to become involved in this process.

Impact Assessment (IA) intends to collect evidence on the likely impacts of new policies and thereby minimize unwanted side-effects and maximize the benefits to society. Although it is a requirement in the EC and all OECD countries, the scope and methods vary considerably. Governments have invested considerably in research to support the evidence basis of policy making for sustainable development. However, the general picture shows a gap between the proliferation of IA tools from the scientific community and their actual use in the policy process. The FP7 network of excellence LIAISE (www.liaise- noe.eu) is designed to identify the causes for non-use of IA tools and bridge the gaps between researchers with a generally strong orientation towards their (disciplinary) peers and practitioners who tend to focus on their policy domain and policy problems. LIAISE aims at: 1) understanding of the policy process and the resulting needs for IA knowledge and IA tools; 2) description of IA tools and scientific IA expertise in a standardised way; 3) a shared IA toolbox targeted at the needs of both researchers and practitioners; 4) a shared IA research agenda integrating scientific knowledge gaps and the priorities for the development of new IA knowledge that arise from the future policy agenda; and 5) safeguarding the project results beyond the period of project funding, by developing an institutional setting and a business plan that facilitate the extension of the present consortium towards a broad centre of IA expertise with a structural permanence. A lively interaction between the different communities involved, is essential to realize these objectives. The Berlin Conference is an important opportunity to inform external research groups about the LIAISE approach to bridging the gap between science and policy. Their feedback and views on possible next steps in the further integration of the IA research community are highly valued, as well as their interest to become involved in this process.

European emission trends of nitrogen oxides since 1880 and up to present are presented here and are linked to the evolution of road transport emissions. Road transport has been the dominating source of NOx emissions since 1970, and contributes with 40% to the total emissions in 2005. Five trend regimes have been identified between 1880 and 2005. The first regime (1880-1950) is determined by a slow increase in fuel consumption all over Europe. The second regime (1950-1980) is characterized by a continued steep upward trend in liquid fuel use and by the introduction of the first regulations on road traffic emissions. Reduction in fuel consumption determines the emission trends in the third regime (1980 -1990) that is also characterized by important differences between Eastern and Western Europe. Emissions from road traffic continue to grow in Western Europe in this period, and it is argued here that the reason for this continued NOx emission increase is related to early inefficient regulations for NOx in the transport sector. The fourth regime (1990-2000) involves a turning point for road traffic emissions, with a general decrease of emissions in Europe during that decade. It is in this period that we can identify the first emission reductions due to technological abatement in Western Europe. In the fifth regime (2000-2005), the economic recovery in Eastern Europe imposes increased emission from road traffic in this area. Western European emissions are on the other hand decoupled from the fuel consumption, and continue to decrease. The implementation of strict measures to control NOx emissions is demonstrated here to be a main reason for the continued Western European emission reductions. The results indicate that even though the effectiveness of European standards is hampered by a slow vehicle turnover, loopholes in the type-approval testing, and an increase in diesel consumption, the effect of such technical abatement measures is traceable in the evolution of European road traffic emissions over the last 15 years.

Newsletter of the International Global Atmospheric Chemistry Project; International audience