Primary goal of this study was the determination of radical precursors sources at different times of the day, under specific environmental conditions, e.g. under the influence of closely located industrial facilities, industrial road and highway. Herein we report the distribution of individual VOCs, formaldehyde, PAN and other species discriminated among day and nighttime conditions as well as under different meteorological regimes. Ratios such as HCHO/CO and HCHO/PAN and others were used to distinguish between primary and secondary sources of formaldehyde. A few events with elevated values of VOCs occurred in late May, which were related to increased mixing ratios of formaldehyde and asscoiated with direct emissions from industrial facilities. VOCs showed distinct patterns depending on the wind direction and indicated specific industrial sources, e.g. petrochemical emissions, sometimes related to specific stacks.