## 1 Introduction
Although air pollution with PM\({}_{10}\) affects the whole population, it was found that certain groups of workers (professional drivers, urban traffic police, street vendors, etc.) or age groups such as children, older adults and those with pre-existing health problems are more vulnerable to developing specific pathologies [4, 5, 24, 25]. Furthermore, population groups with low socio-economic status tend to be more exposed to PM\({}_{10}\), as they most probably live in highly polluted areas, use low quality fuels for heating and have deficient waste management practices [4]. Besides the health effects on humans and the environmental impact, considerable economic impacts are attributed to air pollution, as it reduces life expectancy, increases medical costs and reduces productivity through working days lost [4]. To estimate the health risk resulting from exposure to a specific pollutant, the United States Environmental Protection Agency (US EPA) risk assessment methodology is frequently used [26]. Another tool that allows assessing the relationship between pollutant concentration and health impacts is the Air Quality Health Impact Assessment software [11]. The importance of conducting human health risk assessments is confirmed by the fact that in 2017, concentrations of PM\({}_{10}\) above the EU daily limit value (50 \(\upmu\)m/m\({}^{3}\)) were measured by 22% of the monitoring stations in 17 out the 28 EU member states, while levels above _WHO AQG_ (20 \(\upmu\)m/m\({}^{3}\)) were measured by 51% of the monitoring stations in the majority of the countries [4]. Furthermore, around one fifth of the European urban population was exposed to PM\({}_{10}\) levels above the EU daily limit value, and half of it to PM\({}_{10}\) above _AQG_[4]. Air quality in Romania represents a European and national concern. In this regard, the EU opened the infringement procedure against Romania in 2018 for not taking measures to reduce atmospheric pollution in the major cities. Bucharest, the capital city of Romania, received penalties for PM\({}_{10}\) levels exceedance, while Cluj-Napoca city received the same for NO\({}_{2}\). In 2015, the European Environmental Agency estimated 27,280 premature deaths in Romania associated with PM, ozone and nitrogen dioxide, out of which 25,400 were attributed to PM concentrations [27]. The urban population of Romania exposed to PM\({}_{10}\) values above the EU daily limit values decreased from 53.1% in 2013 to 21.4% in 2017 [28]. This decrease could be the consequence of the initiation of air monitoring and pollution abatement measures requested by Law 104/2011, which transpose into the national legislation the Directive 2008/50/EC ambient air quality and cleaner air for Europe [29]. Numerous studies reported the level of PM in cities all over the world [1, 30, 31, 32, 33]. Human health risk assessment studies regarding PM\({}_{10}\) and toxic elements in PM\({}_{10}\) were also carried out in several cities [34, 35, 36, 37, 38, 39]. These studies revealed that although PM concentrations do not exceed air quality standards, the health impacts associated to air pollution exposure are still important [40]. Therefore, the assessment of the human health risks caused by exposure to airborne PM is an important step in order to control and mitigate urban air pollution. As the chemical composition of PM depends on a high number of factors, such as geography, season, climate and combustion sources, and differs from region to region, the health risk assessment in different cities could give a better insight into the population exposure and health risks [18]. In Romania, [PERSON] et al. presented the adverse effects of air pollution on the respiratory tract for the inhabitants of Drobeta Turnu Severin [39], while [PERSON] et al. showed the impact of PM\({}_{2.5}\) and associated metals on the health of children in the industrial area of Targoviste [40]. However, to the best of our knowledge, no health risk assessment associated with PM\({}_{10}\) has been conducted in Romania.