@bogdanbora

Air pollution in urban environments is governed jointly by emission sources and by the meteorological state of the atmosphere, yet low-cost monitoring platforms rarely measure both simultaneously. This work presents a two-node experimental station, built from commodity microcontroller hardware, that measures climatic parameters, solar irradiance, electromagnetic (lightning) activity and the concentrations of particulate and gaseous pollutants from a single site, and couples these measurements to an implementation of the OML multi-Gaussian dispersion model. The station was deployed on rooftop sites in Cluj-Napoca, Romania. Three families of results are reported. First, pollutant concentrations covary strongly and inversely with solar irradiance over the diurnal cycle: mean PM2.5 fell from 33.9 μg/m³ at night to 26.7 μg/m³ during daylight hours, consistent with convective dilution of the boundary layer rather than with any change in emission rate. Secon