I've been tested 3 times now with the "sniff" test as part of PostCEP. And my husband has been tested once as part of a study looking for biomarkers. His study was named PROBE (not PARS) He also gave many vials of blood.

You scratch papers and are given choices from which to select. Frequently it just smelled like cardboard to me. But you have to select one from every set.

I wrote all about it on pdplan4life in this web page:

Jean