Spatial modelling

Mapping of emissions is an important first step to quantify pressures in the form of deposition of harmful substances to the environment and human exposure to air pollution. Human exposure to air pollution is a significant challenge. WHO estimates that there were 3.7 million premature deaths in 2012 from urban and rural sources worldwide due to outdoor air pollution (WHO, 2014). Recent results (Brandt et al., 2013a) show that outdoor air pollution caused a total number of 570.000 premature deaths in the year 2011 in Europe. While emissions in Europe are generally decreasing (EEA, 2015) there are still challenges at the local and regional scale that can only be quantified using high resolution spatial models.

Air pollution, in general, is a transboundary and scale dependent challenge with global, regional, national and local sources giving rise to large geographic variability and thereby large differences in the geographical distribution of human exposure to air pollution. Therefore, the life time exposure and personal risk factors for mortality and morbidity outcomes due to air pollution, and thereby their welfare, is very dependent on the individuals possibilities to live in a clean environment.

Spatial distribution of emissions is a key element in assessing human exposure to air pollution through the use of dispersion modelling. The quality of the spatial and temporal distribution of emissions is crucial for the quality, applicability and reliability of the modelled air pollution levels, the estimated human exposure, incurred health effects and related costs; all issues that are very important information for policy makers in decisions of implementation of environmental policies and measures.

In addition to the importance of spatial and temporal resolution of emissions to air quality modelling there is also international requirements regarding the reporting of spatially distributed emissions. Under the United Nations Economic Commission for Europe (UNECE) Convention on Long-Range Transboundary Air Pollution (CLRTAP) there is a requirement to report spatially distributed emissions every four years (ECE/EB.AIR/125). The reporting guidelines under CLRTAP specifies the coverage of pollutants, and emission sources and sectors to be covered as well as setting out requirements to the grid used and the deadline for reporting (refer to the Requirements tab for further information). The reporting by Parties is used in the European Monitoring and Evaluation Programme (EMEP) modelling1. The EMEP model calculations have been supporting the decision making within CLRTAP for more than 30 years. Since the 1990s the EMEP models have been the reference tools for atmospheric dispersion calculations as input to the Integrated Assessment Modelling, which supports the development of air quality polices in the European Union.

While emission inventories have been subject to significant improvements over the last decades and efforts to both quantify and reduce the uncertainties of inventory datasets, both the sensitivity to and the processing of emission input data in currently applied atmospheric transport models has not been investigated in sufficient depth. This is in particular the case for the temporal resolution of emissions, which may have a significant impact on the match between modelled and measured air pollution levels in particular when applying atmospheric transport models with exceptionally high spatial resolution on a national or smaller scale (Reis et al., 2009).

The impacts from air pollution are not equally distributed, but depend on geography, socio-demographic and socio-economic factors, including residence address, age, gender, social status, and level of income. Including detailed spatial and temporal distributed emissions improve air quality modelling and contribute to understand the link between air pollution and distribution of related health impacts by adding knowledge that influences modelling of human exposure levels.

The EMEP grid

According to the Convention on Long-range Transboundary Air Pollution (CLRTAP) from 1979 countries that have ratified the convention (parties) shall exchange information on emissions, including emissions from “grid-units of agreed size”. It has been decided that parties shall report emissions according to the predefined EMEP grid. According to the previous version of the reporting guidelines, parties shall report emissions in a grid defined by EMEP with a resolution of approximately 50 km x 50 km. According to the updated reporting guidelines parties shall use the new EMEP grid with a resolution of 0.1°×0.1°, which corresponds to a resolution of approximately 10 km x 10 km for the central parts of Europe.

The new EMEP grid refers to a 0.1° × 0.1° latitude-longitude projection in the geographic coordinate World Geodetic System (WGS) latest revision, WGS 84. The EMEP domain covers the geographic domain between 30°N–82°N latitude and 30°W–90°E longitude. EMEP provide description, grid definition tables and ESRI shape files at the homepage for Centre on Emission Inventories and Projections (CEIP).

References

Brandt et al., 2013a: Assessment of past, present and future health-cost externalities of air pollution in Europe and the contribution from international ship traffic using the EVA model system. Atmospheric Chemistry and Physics, 13(15), 7747-7764. 10.5194/acp-13-7747-2013

Brandt et al., 2013b: Contribution from the ten major emission sectors in Europe and Denmark to the health-cost externalities of air pollution using the EVA model system - an integrated modelling approach. Atmospheric Chemistry and Physics, 13(15), 7725-7746. 10.5194/acp-13-7725-2013

ECE/EB.AIR/125: Guidelines for Reporting Emissions and Projections Data under the Convention on Long-range Transboundary Air Pollution

EEA, 2015: European Union emission inventory report 1990–2013 under the UNECE Convention on Long-range Transboundary Air Pollution (LRTAP). EEA Technical Report No 8/2015

Reis et al., 2009. Improving the temporal profiles of emission input data for high resolution atmospheric transport modelling - a case study for the UK. In: Proceedings of the 18th Annual International Emission Inventory Conference, Baltimore, USA.

WHO, 2014: www.who.int/mediacentre/news/releases/2014/air-pollution/en/