Distracted people can be 'smell blind'. 'Inattentional smell blindness,' or inattentional anosmia, has been proven to exist. Just as it has previously been found that people can miss visual cues when they are busily engaged in a task, the same is true of smells. However, with smells there is only a 20-minute window before people become habituated to the smell and the opportunity to notice it has passed. Source 5p.