Time of contamination in the surface of the earth is important information under the legal aspect. This parameter is often determined by the ability to demonstrate the relationship between the type of activity of the company, and result, in the form of pollution. Depending on when the event occurred and who was responsible, pollution can be considered for damage in the surface of the earth or historical pollution. Taking into account the properties of phenol, which is a substance present in the environment both in its natural state, and an important intermediate in the chemical industry, in this paper the opportunity of determination of the time of contamination in the surface of the earth was calculated based on knowledge of the half decay. In the authors opinion the results presented in the diagrams, allow to estimate the time of creation of contamination. The results of calculations confirm that, given the relatively rapid biodegradability analyze, measuring its concentration for soils types B and C should be a maximum time limit done respectively to 170 and to 90 days after the occurrence of pollution. The results of analyzes also indicate that the areas used industrially measurement of the concentration of phenol made in after 90 days (assuming a 10 day time decay) and sometimes even 20 days (assuming a 2 day time decay) since pollution is not justified. According to the authors, the knowledge of the above facts can be crucial in the selection of measurement parameters and for determining the entity responsible for the pollution of the earth’s surface, e.g. phenol.