Evaluation of Regional Emission Control Based in Photochemical Air Quality Modelling

The growing use of natural gas as fuel both for industrial and domestic purposes implies an increment in the emissions of potential photochemical oxidants in the troposphere, particularly, nitrogen oxides (NOx). This effect can be higher in regions with a significant use of other fossil fuels for electricity production, such as coal fired power plants. Therefore, even though the air quality levels of typical primary pollutants (SO2 and coarse particles) can keep to acceptable values, synergies between additional NOx emissions, biogenic emissions and meteorological conditions can lead to the production of photochemical oxidants, such as O3. The application of meteorological and air quality modelling techniques to evaluate the impact of new NOx sources in the O3 levels over a region can achieve a quantitative estimation of such impact, in terms of the variation of both NOx and O3 levels in the region. This approach to the impact of new sources in air quality, now common for primary pollutants, requires the use of comprehensive air quality modelling in the evaluation of photochemical oxidants. There are several comprehensive air quality models currently available that can be applied to this approach. However, the characteristics of new emission sources, regional conditions (i.e., terrain, sea influence) and pollutants of interest (i.e., photochemical oxidants) result in the selection of the most appropriate model for a particular problem (Chang et al., 1987; Song et al., 2010). In this paper, comprehensive air quality modelling is applied to evaluate the effectiveness of emission control policy in a European Atlantic coastal region, with complex terrain and mixed land use, and a significant area of forestry. This region, located in the northwest of the Iberian Peninsula, includes both medium-sized cities and large coal fired power plants. Therefore, changes in both industrial and domestic emissions due to an increase in the use of the natural gas can affect the generation of photochemical oxidants, depending on the biogenic emissions (forestry) and typical meteorological conditions.