Pursuing the goal to develop an express technique for the characterizing of forest ecology, this paper presents a description of the found dependence of nuclear magnetic resonance (NMR) relaxation times of water in soils on the pollution caused by vehicle exhausts. Test measurements were made in Mari El Republic of Russia where wildwood areas located close to human activity are showing degradation, which has drastically intensified in the resent several years. Samples were collected at distances between 100 m to 1.1 km from the highway towards the direction of virgin forest assuming that their contamination level was naturally varied. The measured spin-spin NMR relaxation time of wetted samples showed a growth of more than 20% with the increase of distance from the pollution source. Here we try to explain this effect. As the conclusion, we propose to use the transverse relaxation time of moisturized soil as an indicator for the environment pollution monitoring.