The organic compounds from industrial processes have an essential role in the formation of multicomponential concentration fields of pollutants in the overground air layer of North-East Estonian landscapes and dwelling areas. In the towns of Kohtla-Jarve and Kivioli organic compounds form 25-28 % of the total quantity of air pollutants originating from oil shale processing and chemical plants. Among pollutants dominate aliphatic and aromatic hydrocarbons, phenols, formaldehyde, organic dusts, etc. On the basis of special imitation system the calculations of overground maximum and mean concentrations of pollutants, affecting the ecosystems near the oil shale processing plants, were carried out for various areas and territories. The calculating and monitoring data have shown reasonable agreement by resting of imitation system. The results of automatic air monitoring system show that the highest pollutant concentrations occur on the dwelling areas of Kohtla-Jarve in calm weather at night before sunrise. The area of essential influence of organic substances to air quality extends to 3-6 km and more from the plants. At Kohtla-Jarve the mean daily concentrations exceeded the permissible level for phenol in 9-50 % of all analyses (1991-1994). Some organic pollutants have synergetic toxic effect what is an important factor in assessment of the state of ecosystems.