If one is in a room and there is waste in a different room and one can see it, it is assur to recite a Davar Shebikedushah, but muttar to think of a Davar Shebikedushah, as long as the smell does not reach one’s nose. However, if the waste can not be seen, it is enough to distance oneself to where the odor ends in order to recite a Davar Shebikedushah.