## 1 Introduction
For example, in China, upgrading all household heating from solid fuels to gas, electricity or district heating would reduce the number of premature deaths related to ambient air pollution by 36.7 per 100k a. (per 100k population annually). [14]. In India, removing emissions from residential energy use would avoid 19.7 premature mortalities per 100k a. [15]. Analysis of the health effect due to air pollution can also focus on all major sources of air pollution to provide recommendations for strategies at particular administration levels. The research concluded in Warsaw, Poland shows that 70.6 per 100k a. deaths are attributable to the inflow of air pollution from outside the municipality borders, and 63.6 per 100k a are caused by air pollution emitted within the administrative borders of the municipality. It has also been demonstrated that the highest contributions in the Warsaw area are households with 40 per 100k a., followed by transport with 22 per 100k a. and finally industry with 1 per 100k a. [16]. The contribution of out-border sources is important in evaluating the possibilities of administration intervention. Shifting private road transport by 40% to public transport and cycling in Adelaide, Australia would reduce annual PM\({}_{2.5}\) by 0.40 ug/m\({}^{3}\) avoiding 0.93 per 100k a. deaths and saving 8.43 per 100k a. Disability Adjusted Life Years (DALYs) [17]. Intervention can also relate to the infrastructure; for instance, in Antwerp, Belgium relocating the ring road into tunnels with filters would avoid 11.5 deaths per 100k a. [18]. Investigation can also provide information on specific road transport conditions. For instance, traffic congestion in the Greater Toronto and Hamilton Area, Canada causes 3 deaths per 100k a. from air pollution; HIA can be useful to choose the best municipal transport policy [19]. In most circumstances, the large point emission sources have adopted mandatory measures to reduce emissions of air pollution and their direct impact on regional air quality would be minor. However, the area over which pollution is dispersed from point sources can be significantly larger compared to area sources or household sources. Retiring two coal-fired power plants in the Southern Front Range region of Colorado State, USA would lead to the reduction of 0.05 premature deaths per 100k a. [20] due to the lower exposition to PM\({}_{2.5}\). Health impacts can also be estimated for future industry plants. The planned coal-fired power plant in Taiwan would cause 1.44 deaths per 100k a. in the area of the whole country [21]. Industry has smaller effects normalized per population than road transport, but, due to its impact over a larger area, it can have higher cumulative results. The main aim of this study was to estimate the potential health benefits of strategy to reduce particulate matter emission from the household sector in two regions in Poland--Lower Silesia with a population of 2.89M and Lodzkie province with 2.46M. Three scenarios were analyzed: (1) changing all lowest quality solid-fuel boilers to gas boilers; (2) replacing those boilers with the highest class of coal-fired boilers; and (3) thermal efficiency improvement of households with the highest energy losses. Household emission is the main contributor to air pollution in Poland [22]. The regions were chosen to represent a mountain region and lowlands. Additionally, both have high PM concentration and similar population.