International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

A comprehensive study of the air condition in urban areas was conducted, based on lidar monitoring. The subject of monitoring are two districts of Sofia the capital of the R.Bulgaria. The time period of the study is May-June 2020 and coincides with the introduced quarantine period in connection with the COVID-19 pandemic. The study includes lidar monitoring of the selected urban areas taking into account the mass concentration of particulate matter (PM). The method is combined with in situ sampling taking into account also the size control in μm – PM2.5 and PM10. The data are compared with those from the indications for the period of the licensed laboratories of the Ministry of Environment and Water and the Civil Network. A physicochemical study of the phase composition, structure and dispersion of the collected PM was performed by the methods of powder X-ray diffraction and Mössbauer spectroscopy. Predominant pollen and spore contamination was reported using Cascad Impactor measurements. Most part, the PMs studied show a conglomerate of several particles.

The object of this investigation was the synergy effect achieved by combining lidar monitoring of particulate matter (PM) pollution in atmospheric aerosol over urban areas (city of Sofia) with in-situ sampling. The lidar systems of the Laser Radar Laboratory (LRL) of the IE-BAS were used to scan at two laser wavelengths the horizontal and vertical aerosol distributions and long-distance transport. The results demonstrated the possibility of detailed fast remote monitoring and analysis of the air pollution over entire urban regions, providing fast estimates of the air pollution transport over the city, as well as detection of sources of extreme emissions. Once the place of high PM concentration was localized by the lidar, samples were taken using a Hygitest 106 (Maimex) – a high-efficiency portable device for sampling and concentration determination of PM in atmospheric aerosol. The data presented pertains to the winter period 2018 year. PM pollutions than 10 and 2.5 μm were under studied. The lidar maps created can be further used for tracing the full air mass transport carrying contaminations from various pollution sources (chemical, biological, dust, etc), distributed over the scanned region. Further, the sampling schedule was conformed with the seasons of the year, in order to reveal any characteristic seasonal hazardous microbial contamination.