Why do smells make some people sick?

A study carried out at Umeå University in Sweden has found out that if you react strongly to certain smells, you may have a chemical intolerance. This hypersensitivity can be an inability to get used to smells. Normally your smell perceptions diminish rapidly, but hypersensitive people feel that the smells are getting stronger and stronger.

For the study, intolerant and non-intolerant individuals were exposed to smells, and reactions measured with electroencephalography (EEG) and functional brain imaging technology (fMRI).  Those with no intolerance showed a lessening of brain activity during the hour after they were exposed to the smell, a brain function that the intolerant group did not possess.

Psychology researcher Linus Andersson says that those with intolerance have a different pattern of blood flow to their brains, meaning that this intolerance affects both the body and the mind. More research is needed to develop treatment, as currently very little is known about chemical intolerance – although up to 10% of the Swedish population have reported that they are bothered by everyday smells, with 2% experiencing severe symptoms.

Source: Umeå University

Click here for more research on chemical sensitivity

First Published in 2012

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