Olfaction: The world smells different to each nostril

The flow of air is greater into one nostril than into the other because there is a slight turbinate swelling in one. The nostril that takes in more air switches from the left to the right one and back again every few hours, but the effect of this switching on the sense of smell has been unclear. Here we show that this difference in airflow between the nostrils causes each nostril to be optimally sensitized to different odorants, so that each nostril conveys a slightly different olfactory image to the brain.