How can a room be purified from urine impurity that has been there for a long time, with the suspicion of its transference to other parts of the room and the house?

Scholars have differed regarding the purity of the ground and what is attached to it through desiccation. According to the view that it becomes pure through desiccation, the matter is easy. If not, then impurity is not deemed to have transferred except with certainty. If its location is known, water should be poured over it to cover it. If it is hidden, the area whose washing is certain to remove the impurity should be washed. For one afflicted with whispers (waswasa), it is permissible to adopt the easiest of opinions to alleviate hardship and difficulty, and this includes the view that impurity does not transfer in this situation.