As far as I have understood it, persons who have contacted virusses (that are to a substantial part transmitted through the air, such as covid-19) tend to be only or most strong infectuous during a short time frame, during which they exhale air with big amounts of viral copies.
Given that viruses are basically packaged RNA, I was wondering if there was a simple way to assess viral content in exhaled air (potentially independent of the virus type). A problem could be that viral and endogenous RNA cannot be distinguised, but maybe this would not even be nessesary as long as we can measure an increase over baseline of overall RNA levels.
I tried to find information about such a method myself, but only end up with tests for specific viruses. Also, I could not find any baseline information about exhaled RNA or similiar either.
I imagine such a test could have advatanges, such as 1) beeing able to track the progression of the disease within a person, 2) beeing useful for to assess the need of quarantine and its duration. 3) beeing less expensive compared to more specific tests and 4) serve as detector to assess contamination of a room, and guide airing praxis.