Heyo, I recently purchased a S3 Arctic Class IV laser pointer. I bought the 3500mW. (In case that page expires, it's 445nm wavelength, 1.5mRad variant, NOHD is 279m, beam distance at 0.25 Lux 72km.)
I plan to use this laser in an open area use - not when surrounded by unwitting people of course. I've taken precautions via reading a lot of the safety manuals available, including reading through the Wiki article on laser safety, the UK regulations, laws on the topic, etc. The laser comes with some protective eyewear which I will wear diligently.
Is it correct to say there is no damage to the eye from observing the beam, assuming there is no dot or dot reflection being directly looked at? All the references to 'safe distances' such as NOHD seem to imply 'safe distance from observing the dot or reflection of the dot'. In contrast, the higher-watt lasers are reportedly used for concerts/lightshows, the beams of which are publicly observable and can be seen from a distance.
(There is a similar question, but doesn't seem to be answered with regards to scattering light. I want it clarified definitely.)
The fact implied is the beam itself, - that is, the scattering light from impurities in the air - will not be a problem for observing without any protection, provided the actual emission source of the laser and destination dot are not observable from the observer's position.