The aim of the study is to determine the optical and radiation properties of the aerosol observed during long-range transport of biomass burning pollution emitted in North America in September 2020. The research was carried out at SolarAOT research station in Strzyzow (south-eastern Poland) on the basis of measurement data obtained from a sun photometer, aerosol lidar and solar radiometer (pyranometer), as well as on the basis of simulation results with backtrajetories model, radiation transfer and aerosol transport model. The results indicate the presence of highly scattering aerosol layers throughout the troposphere and in the lower stratosphere (during the end of the measuring period). The presence of an aerosol in the lower stratosphere has been very rarely observed in recent years due low stratovolcanic activity. Despite this, the aerosol optical thickness was below the long-term average. The presence of the aerosol in the atmosphere reduced the radiation reaching the Earth’s surface at noon by about 32 W/m2. The aerosol direct radiative forcing of the during clear conditions was about –9 W/m2 at the Earth’s surface and –5.2 W/m2 at the top of the atmosphere. The estimated radiative forcing efficiency in combination with the single scattering albedo measurements indicate moderately absorbing particles.