A True Scale of Smell

This week, we find out if our noses tell us the truth. Does a strong smell mean a lot of odour in the air, or can we be tricked by small smells? In short, does our sense of smell have a sense of scale? Also, we ask if more carbon dioxide in the air leads to bigger caves in the ground, and can you slow the growth of your hair by not having it cut? Like this podcast? Please help us by supporting the Naked Scientists