## 2 Data Description
### Dataset Description  
The hourly open-source dataset was downloaded from the Dolj Environment Agency's website. The five-year dataset (1 January 2020-31 December 2024) contains meteorological parameters like temperature (T), relative humidity (RH), precipitation, air pressure (P), sun brightness, wind direction, and speed) and pollutants like particulate matter (PM\({}_{2.5}\), PM\({}_{10}\)), volatile organic compounds (VOCs, including in this category toluene, benzene, m-Xylene, o-Xylene and p-Xylene), carbon monoxide (CO), sulphur dioxide (SO\({}_{2}\)), ozone O\({}_{3}\), nitrogen oxides (NO, NO\({}_{2}\), NO\({}_{\rm X}\)), ammonia (NH\({}_{3}\)), and heavy metals like lead (Pb), nickel (Ni), and arsenic (As). The hourly dataset used in this work was downloaded from the National Environmental Agency website ([[https://calitateaer.ro/](https://calitateaer.ro/)]([https://calitateaer.ro/](https://calitateaer.ro/)), accessed on 26 November 2024) from four stations (DJ1, DJ2, DJ3 and DJ5). It includes two categories of data: (1) meteorological parameters and (2) air pollutants measurements for five years (2020-2024). Meteorological parameters are temperature (T), relative humidity (RH), wind direction and speed, air pressure (P), and sun brightness. Air pollutants include particulate matter (PM\({}_{2.5}\), PM\({}_{10}\)), nitrogen oxides (NOx), ground-level ozone (O\({}_{3}\)), sulfur dioxide (SO\({}_{2}\)), carbon monoxide (CO), and volatile organic compounds (VOCs) such as benzene (C\({}_{6}\)H\({}_{6}\)), ethylbenzene (C\({}_{8}\)H\({}_{10}\)), o-Xylene, m-Xylene, p-Xylene, toluene (C\({}_{6}\)H\({}_{5}\)CH\({}_{3}\)), and ammonia (NH\({}_{3}\)). The dataset contains information about toxic elements like lead (Pb), nickel (Ni), and arsenic (As). Figure 1 shows the locations of the air quality monitoring stations from Craiova. There are four air quality monitoring stations in Craiova: DJ-1 (for traffic, with a representative radius of 10-100 m) has the coordinates (latitude 44.3185692, longitude 23.8062382, altitude 118.00 m) and is located on Calea Severin Street, DJ-2 (for urban background, with a representative radius of 100 m-1 km) has the coordinates (l = 44.3266373, L = 23.7967072, A = 113.00 m) and is located near City Hall, on A.I. Cuza Street, DJ-3 (is mixed, for industrial and traffic) has the coordinates (l = 44.3267708, L = 23.8044415, A = 83.00 m) and it is located on Maria Tanase Street, and DJ-5 (for suburban background) has the coordinates (l = 44.3422203, L = 23.7197227, A = 85.00 m) and is located near Breasta Water Station. In Doli County, there are two other stations. Still, they are not located in or near Craiova (one for background in Filiasi and another for traffic in the cross-border area with Bulgaria, near Calafat). Table 1 indicates the measured parameters for each station that monitors air quality in Craiova. Table 2 contains the variables split into inputs (predictors) and the target variable (output). There are x input and y output variables (PM\({}_{2.5}\) and PM\({}_{10}\)). The objective is to assess the relationship between these factors and find the most important predictors for accurately predicting, modelling, and forecasting PM\({}_{2.5}\) and PM\({}_{10}\) concentrations. z input variables and two output variables (PM\({}_{2.5}\) and PM\({}_{10}\)) are considered. NO, NO\({}_{2}\), and NO\({}_{x}\) were treated differently because each plays a distinct role in air pollution. In environmental reporting, NO\({}_{x}\) means NO and NO\({}_{2}\) and sometimes other nitrogen oxides in smaller amounts (N\({}_{2}\)O\({}_{3}\), N\({}_{2}\)O\({}_{5}\)). NO indicates high temperature combustion (given by thermal power stations) and oxidises to NO\({}_{2}\). It is known that NO\({}_{2}\) participates in  
Figure 1: Distribution of air quality monitoring stations in Craiova. photochemical reactions leading to the formation of tropospheric ozone and secondary PM\({}_{2.5}\) (via nitrates).