A database has a plurality of elements, where each element is associated with a location and at least one set of different attribute values, wherein each set includes a timestamp when the attribute values in the set were determined. A determination is made of a reference geographical location, an element having a geographical location within a geographical region including the referenced geographical location, a most recent set of the attribute values for the element having a most recent timestamp, a previous set of attribute values for the determined element comprising the set of attribute values having a previous timestamp prior to the most recent timestamp, and whether a condition with respect to at least one of the most recent set of attribute values and the previous set of attribute values of the determined element is satisfied.