ELI5 Why do horrible smells seem to linger longer in the nose than pleasant smells?

Horrible smells tend to be made up of more volatile molecules These are the molecules that tend to break down from their source and hang around longer - so there's usually more of them in the air to be smelt than "pleasant" smells. This is often why they are perceived as horrible - because these volatile molecules are also the ones that are most reactive (i.e. the ones that can actually do our body physical harm) - so we perceive them as horrible because they pose an actual risk to our health.

We also react more to these smells (because they potentially pose a risk to us) so we're more likely to actually notice them and continue to notice them.

/r/explainlikeimfive Thread