# Heavy Metals in Urban Street Dust: Health Risk Assessment (Lublin City, E Poland)
## 2 Materials and Methods  
Lublin is located in the north-western part of the Lublin Upland, E Poland (51\({}^{\circ}\)08\({}^{\prime}\)23.31\"-51\({}^{\circ}\)17\({}^{\prime}\)47.61\" N, 22\({}^{\circ}\)27\({}^{\prime}\)15.41\"-22\({}^{\circ}\)40\({}^{\prime}\)24.75\" E). The city covers an area of about 150 km\({}^{2}\) and is inhabited by about 350,000 people. In the second half of the twentieth century, several major industrial plants operated there. Today, the city is primarily an academic, administrative and service centre. At present, mainly the food industry (for example, a brewery and a pasta factory) is developing there. There are also a few not very large pharmaceutical, agricultural machinery and chemical plants. All of them are concentrated in the eastern part of the city, which means, given the prevailing western winds, that the emissions of industrial pollution do not have too big an impact on the state of the environment in the city. The conducted research indicates a relatively low level of contamination of soils and street dust with trace metals [32; 34; 35]. Currently, no measurements of heavy metal emissions to the atmosphere have been carried out in Lublin. The sampling points were located within different functional areas of the city-- residential districts, commercial and service centres, and industrial areas. In total, samples from 62 points (Figure 1) located near street intersections were analysed. The study material came from street pavements, along the edges of the roadway. The material was sampled twice, in March 2013 and March 2018 (each time, samples were collected over two days). The sampling method used is common in investigations of this kind [12; 36]. The dust was sampled after a five-day period without precipitation. There was no street washing and there were no snow melting episodes within the month prior to sampling. The samples were collected with a plastic brush into plastic bags, then dried at room temperature, and subjected to preliminary sifting through a 1 mm sieve in order to remove macro debris. The metal content was tested in material with a diameter of less than 63 \(\upmu\)m, which was obtained by sieving the samples through a steel sieve. The street dust was ground in a zirconia ball mill, and then pressed pellets were prepared from it. Analyses of the total Cd, Cr, Cu, Ni, Pb and Zn content were performed on an X-ray fluorescence spectrometer (Epsilon5 Panalytical). The metal content of each sample was measured three times and the average was given as the final result. The accuracy of the method was verified using reference material NCS DC 73,385 (measurement error ranged from 3 to 5%). The study used hazard index (HI) and cancer risk (CR) for a quantitative description of health risk related to human exposure to heavy metals contained in street dust [22, 23]. The average daily dose quantifies the risk of cancer and non-cancer diseases as a result of human contact with a selected element (in the case studied, it is contact with the solid fraction in the form of street dust). These models are commonly used in studies of the hazard represented by heavy metals in various types of city street dust [24, 26, 28, 37, 38]. According to the adopted methodology, three methods of contact with the dust hazard and, therefore, three forms of average daily dose (ADD) intake can be distinguished: inhalation described with the parameter ADD\({}_{\text{lnh}}\)--taking into account, among others, the particle emission factor; skin contact (ADD\({}_{\text{derm}}\))--taking into account, among others, the skin area exposed to the carcinogen; and ingestion (ADD\({}_{\text{ing}}\)).