## 2 Implementation of the System  
The Arduino Uno platform is the foundation of the system due to its robust computational abilities and extensive compatibility with various protocols via its interfaces. This platform was chosen for its user-friendliness and widespread acceptance across numerous projects, ensuring seamless integration and application versatility [30]. To capture a broad spectrum of air quality metrics, the system integrates two multifunctional sensors: the BME680 and CCS811. The sensors are selected for their precision in capturing environmental data, including temperature, humidity, atmospheric pressure, carbon dioxide (CO\({}_{2}\)) concentrations, VOC, and IAQ. The system aims to provide a convenient and effective tool for IAQ evaluation, catering to the growing consumer interest in intelligent home technologies that enhance both environmental health and individual comfort. Figure 1 provides an overview of the system's design, while Figure 2 offers a detailed view of the electrical circuitry that underpins the intelligent air quality monitoring system. The diagram clarifies the connections and functionalities within the system, revealing its operational dynamics and the intricate workings of its components. The system's design centers around the BME680 and CCS811 sensors, which are integrated using the I\({}^{2}\)C communication protocol to interface with the Arduino Uno micro-controller [26]. These sensors continuously monitor and quantify key air quality metrics, including temperature, humidity, atmospheric pressure, CO\({}_{2}\), and VOC concentrations. The sensors collect data which are then sent to the microcontroller for analysis. The BME680 sensor, developed by Bosch, is a versatile environmental sensor that integrates the measurement of various environmental parameters, including gas, humidity, temperature, and pressure. It integrates the measurement of VOC (formaldehyde, benzene, toluene, acetone, ethanol, and xylene) from various sources such as paints, lacquers, paint strippers, cleaning supplies, furnishings, office equipment, glues, adhesives, etc. The device is capable of measuring CO\({}_{2}\) levels with rapid response times of under one second, rendering it suitable for real-time monitoring of air quality. Furthermore, the sensor is capable of accurately measuring humidity (0% to 100% RH), temperature (\(-40\)\({}^{\circ}\)C to \(+85\)\({}^{\circ}\)C), and atmospheric pressure (300 to 1100 hPa). The BME680 is operational within a voltage range from 1.7 V to 3.6 V and is encased in a compact package measuring 3.0 mm \(\times\) 3.0 mm \(\times\) 0.93 mm, supporting both I\({}^{2}\)C and SPI communication interfaces. In contrast, the CCS811 sensor (SparkFun, Niwot, CO, USA) has been designed with the specific purpose of monitoring indoor air quality. It is capable of measuring equivalent CO\({}_{2}\) levels from 400 to 8192 ppm and VOC levels from 0 to 1187 ppb. This sensor is designed with an emphasis on air quality assessment, with a particular focus on the detection and quantification of airborne pollutants. The CCS811 operates within a voltage  
Figure 1: External appearance of the developed system. Figure 2: Functional electrical circuit diagram of the system. range from 1.8 V to 3.6 V, utilizing the I\({}^{2}\)C communication interface. Its compact form factor (2.7 mm \(\times\) 4.0 mm \(\times\) 1.1 mm) and specialized gas sensing capabilities make it particularly well-suited for applications where accurate indoor air quality measurements are essential. The sensors are capable of detecting changes in total volatile organic compound (TVOC) concentrations, which include analytes such as formaldehyde, benzene, toluene, acetone, ethanol, and xylene. It should be noted, however, that the BME680 and CCS811 sensors are not designed to specifically identify or differentiate between individual VOC. In lieu of identifying specific VOCs, these sensors provide a comprehensive assessment of indoor air quality by detecting the overall presence of VOCs.