(They are actually riveted to their heads by their Employers to conform to Health and Safety Regulations).
They are aware of dangerous objects falling from the sky...
Take a tip from them, and always wear a Hard Hat....
..you never know when the next Asteroid will arrive....

I always don my trusty Crash Helmet when venturing outside... 8-)...!
(Its protected me from falling Sea-Gull crap so far).
Paul...ever-gazing skywards...
