Sheldon Whitehouse actually said...
So a vulnerable person who goes out on a bad air day and experiences no apparent, immediate ill effects, doesn't feel shortness of breath, doesn't cough, doesn't in any way have a present sense during the bad air day that they have been affected, nevertheless could suffer, could be suffering harm as a result.
Context
Highlighting the long-term health risks of bad air days.
12/16/2014