The soot particles of the fire smoke, occurring in a short time, reduce the range of visibility and the ability to differentiate colours and contrasts ( e. g. of exit signs) very fast. With the increase of eye irritation by smoke the visual acuity also diminishes.
The existing sight range also has a great influence on the behaviour of human beings.
- > 20 Metres sight range >> well being
- 10 to 15 Metres >> uncertainty
- < 10 Metres >> upcoming panic
The fast reduction of the orientation ability during a smoke logging, results in:
- people not finding exits and escape routes and therefore potentiallystaying in dangerous areas,
- increased risk of injury in dangerous places,
- fire fighters requiring a lot of time to find and rescue people who have not yet escaped,
- fire fighters needing a lot more time to localise the source of fire.