## 1 Introduction
The absorption of particulate matter by living organisms poses a serious threat due to the variety of toxic, carcinogenic, and mutagenic chemicals it often contains [26; 38]. Additionally, certain components of particulate matter can trigger allergic reactions. Particularly hazardous are toxic metals and their compounds, persistent organic pollutants, sulphates, and others. PM-bound PAHs and PM-bound heavy metals, particularly fine particles, can re-enter the air or enter the human body via ingestion, inhalation or skin contact [39; 40]. Heavy metals pose a significant health threat due to their tendency to be absorbed, retained and biomagnified within the body, potentially leading to various diseases [41]. The specific health effects depend on the type of metal involved. For example, the International Agency for Research on Cancer [30] has classified arsenic, cadmium, and nickel as carcinogenic to humans (Group 1), and they are linked to fatal cancers of the lungs, trachea and bronchi. Lead, categorised as possibly carcinogenic (Group 2A), can cause neurological damage and impair kidney function [35]. In children, long-term lead exposure has been associated with developmental delays and learning difficulties [42]. Overall, heavy metals have the potential to disrupt the nervous system, hinder kidney function, interfere with bone formation and negatively affect various other organs [17; 43; 44]. The IARC classifies PAH congeners according to their carcinogenicity: as carcinogenic to humans (Group 1), probably carcinogenic to humans (Group 2A), or possibly carcinogenic to humans (Group 2B) [30]. For example, benzo[a]pyrene is categorized as a Group 1 carcinogen, whereas benzo[a]anthracene, benzo[b]fluoranthene, benzo[j]fluoranthene,benzo[k]fluoranthene, dibenzo[a,h]anthracene, and indeno[1,2,3-cd]pyrene are classified as Group 2B compounds. PAHs can be inhaled as vapours or adsorbed onto airborne particulate matter. The site at which they are deposited within the respiratory tract is influenced by the particles' aerodynamic diameter [45]. Ultrafine particles can penetrate deep into the alveolar region and subsequently enter the bloodstream, spreading throughout the body. In contrast, larger particles are usually deposited in the bronchiolar regions [35]. Due to their lipophilic nature, PAHs accumulate in adipose tissue [46]. Studies demonstrate that benzo[a]pyrene accumulates in pulmonary tissue, as well as in the heart, liver, spleen, kidneys and skeletal muscle [47; 48]. During biotransformation in the human body, PAHs are metabolised into reactive intermediates that can form covalent adducts with DNA, RNA and proteins [49; 50]. This mechanism is widely recognised as a critical contributor to carcinogenesis [51; 52]. However, it has yet to be definitively established whether carcinogenic outcomes are attributable to individual PAH congeners or the combined effect of multiple compounds [53]. Despite ongoing reductions in emissions, most of the European urban population continued to be exposed to hazardous air pollutants in 2022. In particular, they were exposed to concentrations of PM\({}_{2.5}\) above the WHO's 2021 annual guideline level of 5 \(\mathrm{\SIUnitSymbolMicro m^{-3}}\)[54]. In Poland, high concentrations of PM, PAHs, and heavy metals pose a particular risk in urban areas such as Cracow, Upper Silesia, and Wroclaw, where normative values are consistently exceeded. In 2023, the average annual concentration of B[a]P, a key indicator of human exposure to priority PAHs [55; 56], in Poland was 1.53 \(\mathrm{\SIUnitSymbolMicro m^{-3}}\) This level exceeds both the European Union's target value of 1.0 \(\mathrm{\SIUnitSymbolMicro m^{-3}}\)[57; 58] and the WHO's recommended guideline of 0.12 \(\mathrm{\SIUnitSymbolMicro m^{-3}}\)[59]. The report's authors [60] indicate that the number of deaths in Poland attributable to exposure to suspended particulate matter is twice the European Union average.