# A Regional Multi-Agent Air Monitoring Platform
## 3 State of the Air in Plovdiv  
Although there are standards for acceptable air quality, pollution in urban settings is caused by a variety of factors. The overall pollution picture in a city results from a complex overlay of different backgrounds--natural, regional, and urban. Depending on the specific conditions, these backgrounds may amplify or neutralize each other. Urban air pollution is a complex issue that requires comprehensive and systematic analysis. Only by understanding all the factors--natural, regional, and urban--and how they interact can an accurate picture of the situation be developed and effective measures taken to improve air quality. This integrated approach, combining different levels of analysis, is key in developing sustainable solutions to tackle urban air pollution. Air quality depends not only on pollutant emissions from different sources such as industry, transport, and tertiary and domestic sources, but also on weather conditions that control the dispersion of pollutantsor, conversely, their accumulation. For these reasons, it is necessary to have an objective understanding of the air quality in the region of interest (in this case, the Plovdiv region). Plovdiv is the second largest and most important city in the Republic of Bulgaria, located on both sides of the Maritsa River. The natural environment of Plovdiv is characterized by a specific relief, dominated by the six syenite hills, which are not only an emblematic element of the landscape but also protected areas with high biodiversity. Together with the Maritza River valley, they create a microclimate characterized by mild winters and hot, humid summers. The urban environment is urbanized, with high building densities, intensive car traffic, and industrial activity. Some analyses from external sources regarding the Plovdiv region are published in [26; 27]. In this section, we summarize the results of our measurement analysis. Our network includes 11 sensor complexes located at key points in the city of Plovdiv and multiple sensors in the surrounding towns. The sensors measure the concentration of various pollutants, including fine particulate matter (PM10 and PM2.5), nitrogen oxides, ozone, and other gases that affect air quality. In addition to major air pollutants, sensors in our network also report data on temperature, atmospheric pressure, humidity, gamma radiation, and more. The data, available at [4], is collected in real time every 5 s and analyzed using specialized software platforms. The aim of the network is to provide the public and local authorities with accurate and timely information on the air quality in the measured residential areas. The system is part of an effort to raise awareness of environmental issues and create a healthier and more sustainable urban environment. In Figure 1, we have marked in red the areas of the city that have sensors from our network and external sources, and in green, we have marked some of the sensors we monitor in areas of the city where data from other sources are not available. With the following charts, we visualize the comparison of data from our sources and those of the European Environment Agency. The chart (Figure 2) shows the concentrations of fine particulate matter (PM) PM2.5 and PM10 in Plovdiv-Kamenitsa, comparing them with the current European Union standards and the European Environment Agency data for 2022 and 2023. Figure 1: A map of data sources for the city of Plovdiv (visualization of our sensor network). PM levels in TSENTAR were above the EU average. In 2024, data from the Agency are not available. Despite the apparent reduction in pollution in 2024, efforts must continue to maintain and further reduce PM pollution, especially PM2.5. Regular monitoring and implementation of pollution control measures are critical to improving air quality in Plovdiv. With the current actions and pollution control measures, there is a positive trend in the improvement of air quality in Plovdiv. However, long-term efforts will still be needed to reach and maintain EU clean air standards.