Timely and quality data about environment and space is nowadays necessary support when deciding on interventions and environmental monitoring and rapid response to natural disasters. Slovenia is through European projects and membership in different organizations, which are focused on global and rational data collection, and their widespread use, successfully integrated into the European Earth observation activities. This research has been made for competition announced in the framework of the Observe project -"Strengthening and Development of Earth Observation Activities for the Environment of Balkan Area". Purpose of the project was to demonstrate how to use spatial data from Earth observation in other sciences and in this way to extend their usefulness and to indicate the benefits that our society may have of them. In this study we used data from Project Promote (forecasts of ozone, nitrogen dioxide and particulate matter PM10 concentration in the air) and in-situ measurements of the Slovenian Environment Agency (ARSO). The area used in this research is the broader region of Ljubljana, Slovenia. In the first part of the study we are using in-situ measurements to evaluate Promote forecasts. In the second part we tested the following hypothesis on Promote data: "With increasing quantity of precipitation, PM10 mass concentration decreases." The comparison between PROMOTE forecasts and in-situ mass concentrations from ARSO showed some weaknesses of the PROMOTE data. Our hypothesis has been confirmed with less than 2.7 % risk.