Many people with asthma and/or aspergillosis report that they can detect some odours more sensitively than people who do not have asthma/aspergillosis. This can cause significant practical problems during their daily lives as they must constantly seek to avoid any smells that they detect while at the same time having to convince people who cannot detect the smell that there is a problem!
There have been a few research articles published on this phenomenum over the last 20 years and some conclude that people who claim that they have 'supersensitive' ability to smell do not in fact have any more ability to detect a given smell compared with someone who believes that they have a normal sense of smell. This conclusion is made by getting people to signal when they can detect a smell under rigorously controlled conditions. They are given less and less odour until they cannot smell anything. The point at which they cannot smell an odour i.e. they 'smell sensitivity' to a particular odour is no different between groups of people who think they are supersensitive and those who feel that their sense of smell is normal.
So supersensitive smell is all in the mind of the 'supersensitive person? A recent research papers suggests the answer is yes...and no.
Andersson et.al (2016) performed a series of experiments comparing 'supersmellers' with 'normal smellers'. They too noticed that supersmellers did not have a special ability to smell faint odours. However once detected they did rate the smell as stronger.
The authors suggest that 'supersmellers' brains have learned to respond to odours more powerfully as they have learned that strong smells can be a threat to their health. The response is so powerful it can trigger inflammatory responses and ultimately trigger an asthma attack. This is part of our natural protection mechanisms so would be very difficult to change - avoidance is still the best current treatment strategy!