When Dollar General held its ground it was a sign the selling pressure was drying up.

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Also consider long-acting decongestant sprays or tablets, which help keep blocked nasal passages open when cabin pressure changes during take-off and landing. (Decongestant can be overly drying in airplane cabin air so consider saline solution, too).

BBC: The flu is a frequent traveller

In 1931 American chemical engineer Samuel Kistler invented the lightest known solid--an aerogel--by drying a form of silicon dioxide (a raw material for glass) under intense pressure and high temperature.

FORBES: Magazine Article