Ultrafine particles are produced by conversion processes of gas-to-particle. Both fine and coarse particles are impacted and created by burning biomass (BB), which is the burning of living and dead vegetation. It includes the human-initiated burning of vegetation for land clearing and land-use change, as well as natural lightning-induced fires [8]. Another phenomenon, called nucleation, is also a source of particle formation, involving formation of aerosol particles from the gas phase with core formation. There are two types of nucleation events: long-term, during daytime for 1 to 8 h, and short-term, occurring throughout the year from minutes to 1 h. Over the Baltic Sea, these phenomena are enhanced during spring and autumn, with high solar radiation and air mass transport from the north or northwest, depending on the area (coastal or continental) [9]. One particular feature of aerosols is that they absorb and scatter solar radiation. This feature is the base of the AOD measurement that gives us a ratio of the concentration of aerosols in the atmosphere that we will use during this study. The AOD depends on the wavelength used to record data, and a common reference is around 500 nm. Because of this particular property (also called direct effect), aerosols modify solar radiation and pose a crucial impact on climate. Additionally, they have an impact on the climate by modifying microphysics and, thus, the radiative properties of clouds (cloudiness and cloud lifetime), the so-called indirect effect [3; 10; 11]. Aerosols are responsible for atmospheric visibility levels. They can also have an impact on UV radiation levels [10], as well as photochemistry in the planetary boundary layer. Various aerosol particles (different chemical compositions) can absorb solar radiation in the atmosphere, which results in cooling of the surface and/or atmospheric warming [3; 12]. Due to significant radiative forcing on the surface, aerosols are important locally (regional weather), but they also influence global climate patterns [3; 12]. Therefore, atmospheric aerosol particles are key players in the Earth's energy budget and thus in climate patterns. Remote aerosol sources contribute greatly to the pollution of low-emission regions via long-range transport. These advections further impact local climate patterns [13; 14; 15; 16]. Local emissions and the long-range transport of atmospheric aerosols across regions or even continents have a pronounced impact on air quality and living organisms' health [13; 14; 15; 16]. The Arctic is among the most prominent examples. The extreme biomass burning episodes, which occurred in Canada and Siberia, and which affected the summer levels of AODs over Svalbard and the European Arctic between 20013 and 2019, have been reported by numerous researchers [17; 18; 19; 20; 21; 22; 23]. In all cases, the authors show that the extreme wildfires were due to climate change consequences, such as dryness of the soil, as well as intensive human activities. The reports show that these events are becoming a usual summer problem for the Arctic region and that these episodes may become more pronounced in comparison to the so-called Arctic haze phenomenon, which is a springtime haze in the atmosphere at high latitudes in the Arctic due to advections of anthropogenic air pollution. The examples above involve both natural sources, such as sea salt particles and emissions of volatile organic compounds from plants or wildfires, which sometimes may also be attributed to anthropogenic aerosol sources, which are mainly associated with fossil fuel combustion to generate electricity, various industries, households, and liquid fuel combustion for transport energy purposes. Transportation-related aerosol particles can have local and regional importance, while massive industrial activities (such as those in Siberia) can influence atmospheric conditions globally. Biomass burning aerosols are difficult to qualify since they originate from wildfires, which, in turn, can be of both natural and anthropogenic origins.