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LIFE Emerald - Feasibility of Using the SHERPA Model for ATMO-Street Policy Scenario

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Published: 2024

Pages: 53

Filesize: 7,964 KB

Format: pdf

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Feasibility of using the SHERPA model for ATMO-Street Policy Scenarios, Air Pollutant Maps for Policy Support and Health Impacts

The purpose of this Deliverable was to assess the feasibility of using the developed ATMO-Street high-resolution model to support national level policymakers in Ireland in assessing the impact of plans or policies on air quality. The report presents the investigation of the follow policy scenarios:

  1. The predicted impact of the Climate Action Plan 2021 (CAP21) emission reduction measures on the ambient air quality concentrations.
  2. The combined impact of CAP21 and the Solid Fuel Regulations (SFR) measures for 2030.
  3. The impact of the various emission reduction measures on health.

A procedure was developed to calculate the effect of emission abatement measures on pollutant concentrations, namely:

  • Run the model to establish baseline emissions without policy abatement measures.
  • Then determine the change in emissions for the measures.
  • Re-run the model with the new emissions to reflect the measures.
  • The difference between the baseline and re-modelled emissions will give the impact of the measures.

For the baseline, the developed RIO model was used for the reference background concentrations. The Joint Research Centre’s SHERPA model was used to determine a scaling factor to be applied to the RIO model to establish the future background concentrations.  The results for the different scenarios were calculated for NO2 and PM2.5.

The baseline year of 2021 was chosen, and the years 2025 and 2030 were chosen for future scenarios. The scenarios investigated were the CAP21 emission projections With Measures (WM) and With Additional Measures (WAM) for each future year. The SFR were added to the CAP21 WAM 2030 reductions. The National Emissions Ceiling Directive (NECD) emission reduction commitments for 2030 were also modelled.  

For all scenarios the decreases in concentration compared to 2021, between WM, WAM and WAM with SFR are smaller than the differences between the two years, 2025 and 2030. For NO2, the predicted concentration reductions are mainly seen in the larger municipalities. For PM2.5, the average modelled reduction in concentrations is in the range of 0.3 - 1 µg/m3, which is spread throughout the country, and less confined to the larger municipalities.

The health impact of the modelled scenarios was carried out by attributing mortality related to long-term exposure to NO2 and PM2.5, based on the modelled annual averages. The number of premature deaths and years of life lost was calculated using the relative risk of each pollutant, it’s modelled concentration and population data. A sensitivity analysis was performed on the relative risk by considering World Health Organisation (WHO) Concentration-Response Functions (CRF). For each county, mortality estimates of attributed mortality was shown for the baseline WHO CRFs. The analysis showed that the yearly number of premature deaths and years of lives lost is at least 10 times higher due to exposure to PM2.5 compared to NO2.

The report provided some conclusions and recommendations on the use of this methodology going forward, to support the CAP and similar policies in Ireland where emission projections are available. ATMO-Street can be used in conjunction with the JRC’s SHERPA to model future scenarios. However, SHERPA does have limitations for this analysis. Consideration should be given to develop a chemical transport model (CTM) to enhance specific emission abatement scenario modelling.