Who puts up these signs?

http://www.telegraph.co.uk/travel/picturegalleries/signlanguage/4603140/Sign-language-week-36.html

From Everglades National Park

Blow Your Nose the Cyclist's Way

A true cyclist can generate nasal congestion. A true cyclist checks behind them for other riders, turns their head to one side, puts a finger on one nostril, and blows out the other. This produces what's called "snot rockets", although there is only primitive rocket science involved.

Now studies shows that this is actually the healthier way to do it. According to research reported in the New York Times,

"Dr. J. Owen Hendley and other pediatric infectious disease researchers at the University of Virginia conducted CT scans and other measurements as subjects coughed, sneezed and blew their noses. In some cases, the subjects had an opaque dye dripped into their rear nasal cavities.
"Nose blowing generated enormous pressure — 'equivalent to a person’s diastolic blood pressure reading,' Dr. Hendley said — and propelled mucus into the sinuses every time. Dr. Hendley said it was unclear whether this was harmful, but added that during sickness it could shoot viruses or bacteria into the sinuses, and possibly cause further infection.

"'The proper method is to blow one nostril at a time and to take decongestants', said Dr. Anil Kumar Lalwani, chairman of the department of otolaryngology at the New York University Langone Medical Center. 'This prevents a buildup of excess pressure.'"

One nostril at a time is, of course, the only sensible way to do it on a bicycle. Who knew we were so smart?