Maybe not, according to preliminary, unpublished research by Leopold. He and his team took CAT scans of 90 patients who said they had lost their sense of smell in either the right or left nostril. The scans showed, however, that regardless of which nostril was supposedly affected, a significant number of patients had anatomical obstructions in the left nostril and the left nostril only. They were ignoring their right nostril. But the data aren't there yet.
All senses have variations on the theme, ways to damp stimuli, and a good thing, too.
We've all had times, such as cleaning up after a child vomits, when that damper is essential. You'd never get anything done if you couldn't ignore most of the sights, sounds, smells, and touches around you, from the sensation of your feet in your shoes to sirens outside. You'd miss new sense signals, too. Many old people continue to have good olfactory function. That's not the rule, however.