Some extensive numerical simulations of the atmospheric composition fields in the city of Sofia have been recently performed and an ensemble, comprehensive enough as to provide statistically reliable assessment of the atmospheric composition climate of Sofia - typical and extreme features of the special/temporal behavior, annual means and seasonal variations, etc. has been constructed. The simulations were carried out using the US EPA Models-3 system. The meteorological data needed for the models that was used is from the NCEP Global Analysis Data with 1°×1° resolution. The WRF and CMAQ nesting capabilities are applied for downscaling the simulations to a 1 km step for the innermost domain. For Bulgaria and smaller domains the emissions input is from the national emission inventory, prepared by the Ministry of Environment and Water of Bulgaria (MOEW), while outside the country the emissions were taken from the TNO inventory. Special pre-processing procedures are created for introducing temporal profiles and speciation of the emissions. The biogenic emissions of VOC are estimated by the model SMOKE. For describing the ambient pollutant mix, an overall air quality index (AQI) is constructed, which makes it possible to describe the air quality in a simple, understandable for the general public way. The general conclusion that can be made for the Sofia city is that the air quality status of Sofia is not so good (evaluated with a spatial resolution of 1km). AQI status falls mostly in “Low” and “Moderate” bands, but the recurrence of cases with Very High pollution is close to 20% mostly at the city centre.

The air is the living environment of human beings and atmospheric composition has a great importance for the quality of life and human health. Air quality (AQ) is a key element for the well-being and quality of life of European citizens. The objective of the present work is performing reliable, comprehensive and detailed studies of the impact of lower atmosphere composition on quality of life for the population in Bulgaria. The AQ study is based on atmospheric composition numerical simulations. United States Environmental Protection Agency (US EPA) Models-3 system was applied as the tool for 3D simulations. The AQ index (AQI) provides an integrated assessment of the impact of air pollutants on human health and is calculated on the basis of the air pollutant concentration obtained from numerical modelling. A comprehensive ensemble of atmospheric composition fields was created and diurnal variations of the recurrence spatial distribution of different classes of the AQI are demonstrated in the present work.

Previous atmospheric composition studies were based on extensive computer simulations carried out with good resolution using up-to-date modelling tools and detailed and reliable input data. The oncoming climate changes will exert influence on the ecosystems, on the all branches of the international economy, and on the quality of life. Regional climate models (RCMs) are important instruments used for downscaling climate simulations from Global circulation models (GCMs). The air quality (AQ) impact on human health and quality of life is an issue of great social significance. Evaluating this impact will give scientifically robust basis for elaborating efficient short term measures and long term strategies for mitigation of the harmful effects of air pollution. The AQ impact is evaluated in the terms of Air Quality Indices (AQI). Some extensive numerical simulations of the atmospheric composition fields in Bulgaria and Sofia have been recently performed. A quite extensive data base was created from simulations which were used for different studies of the atmospheric composition, including the AQ climate. Main aims of the numerical experiment presented in this paper are: (1) Adaptation and tuning of the RegCM model for the Balkan Peninsula and Bulgaria and thus development of a methodology able to predict possible changes of the regional climate for different global climate change scenarios and their impact on spatial/temporal distribution of precipitation, hence the global water budgets, to changes of the characteristics and spatial/temporal distribution of extreme, unfavorable and catastrophic events (drought, storms, hail, floods, fires, sea waves, soil erosion, etc.); (2) Development of a methodology and performing reliable, comprehensive and detailed studies of the impact of lower atmosphere parameters and characteristics on the quality of life (QL) and health risks (HR) for the population.

Bulgaria has developed national emission reduction strategies for the period from 2020 to 2029 and the years after 2030, in accordance with EU Directive 2016/2284. Our fundamental aim in this study is to assess the effects of the strategy on the PM near surface concentrations in Bulgaria. All the simulation was done by the modeling system U.S. Environmental Protection Agency (US EPA) Models-3 for 2008 to 2014 period and with 9 km horizontal grid resolution for the selected region – Bulgaria. The meteorological background that was used is with 1°x1° resolution from the National Centers for Environmental Prediction (NCEP) Global Analysis Data. There are 5 emission scenarios structured: 2005 emissions (reference period), 2020–2029 emissions projected with existing measures (WEM) and with additional measures (WAM), projected after 2030 WEM and WAM emissions, as parallel calculations were performed with all of the scenarios. Making parallels between the concentrations, with different scenarios simulated, gives the possibility to evaluate the national emission reduction strategies’ effect.