## 1 Introduction  
Air pollution, particularly particulate matter (PM\({}_{2.5}\) and PM\({}_{10}\)), represents an issue in congested areas worldwide [1]. PM\({}_{2.5}\) represent fine particles with a diameter under 2.5 \(\upmu\)m and PM\({}_{10}\) with a diameter of less than 10 \(\upmu\)m. In urban areas, industrialization, heavy traffic, construction sites, demolition to develop residential areas, and fossil fuel heating are just some of the anthropic sources of air pollution [2]. There is also air pollution in rural areas, but it is not as severe as in urban areas [3]. Poor air quality impacts human health. PM\({}_{10}\) affects the upper airways of the respiratory system (nose, throat, bronchi), while PM\({}_{2.5}\) is more aggressive, managing to penetrate deeper into the lungs and even into the blood. Therefore, exposure to PM\({}_{10}\) irritates the eyes, nose, and throat [4, 5, 6], increases the risk of respiratory infections [7] and worsens symptoms in people with chronic respiratory diseases [8]. PM\({}_{2.5}\) leads to an increased incidence of chronic respiratory and cardiovascular diseases [9], is associated with cognitive decline (dementia) [10] and neurodegenerative diseases (Alzheimer [11; 12] and Parkinson [13; 14]), and increases the risk of respiratory cancer [15; 16]. Sensitive categories of the population, like children, pregnant women, the chronically ill, and the elderly, suffer most from air pollution [17; 18]. In 2021, the WHO revised its recommendations on air pollutant levels to protect human health [19]. Air pollution affects the balance of ecosystems. Biodiversity is directly affected; air pollution causes physiological stress and toxicity to organisms, decreases leaf chlorophyll content and leaf size, negatively affects ascorbic acid levels, and decreases seed quality and biomass [20; 21]. Indirectly [22; 23], biodiversity is impacted by acid rain [24], which leads to lower soil pH [25], damages the protective layer of tree leaves [26], and affects roots in the soil, making forests more susceptible to infestation by insects [27]. Air pollution alters the balance between species, with invasive species occupying the space left by those more susceptible to pollution [28]. Pollinating insects [29] are among the sensitive species, which leads to the extinction of some plants and birds in the long term. Last, air pollution affects the quality of flowing and standing water. Some algae species overgrow to the detriment of others, which decreases oxygen levels in waters and thus affects aquatic life [30; 31; 32; 33]. The present study aims to model, predict, and forecast PM pollution in Craiova, Romania. Romania is in Southeast Europe and part of the European Union. In the last decade, in Romania, decision-makers have taken several measures to reduce pollution, such as investing in clean energy and renewable sources and developing measures to support the energy efficiency of buildings. Monitoring illegal burning and punishing polluters has improved, and selective waste collection and recycling are promoted. City bypasses and express roads have been built; clean public transport infrastructure has been developed in most cities. Craiova is no exception to all these transformations. In the literature, there are several studies about air pollution in Craiova. The most important of them are statistical approaches based on short-term datasets (from a few months to two years [34; 35] provided by an independent low-cost sensor network (uRADMonitor) or by the National Environmental Agency network of air quality stations. In these studies, pollution episodes with different pollutants are identified, and the results from Craiova are eventually compared with those from other cities in Romania or between a low-cost sensor network (uRADMonitor) and the National Environmental Agency [36; 37]. A statistical study using data from CAMS emphasizes the limitations and strengths of reanalysis data as an alternative solution in areas where pollutant concentration measurements are unavailable [38].