Green to be seen
Introduction
Green is a colour we all see every day.
It has multiple uses and has become synonymous with nature, feeling good, calmness, clean energy, sustainability and conservation. Green stones and jewels have been used to represent nature for centuries. It is considered by many as the universal colour of safety and ‘go’ and we are even told that green improves focus and is good for us.
Furthermore, and more specifically, legislation dictates that in the UK at least, emergency exit signage (the ‘running man’ legend) is white on green.
Why?
What is light?
We speak of light but what, exactly, is it?
The electromagnetic spectrum ranges from radio waves, with a comparatively long wavelengths (meters), to gamma rays with a relatively short wavelengths (1×10-10 meters or picometers).
Light is electromagnetic radiation and as such is part, a very small part, of this spectrum, (broadly in the middle between infrared and ultraviolet), and typically refers to what can be perceived by the human eye ie visible light, what we see.
It is the main thing we use to perceive the world around us and without it we would be, literally, in the dark.
In fact, Isaac Newton discovered that sunlight consists of different colours, the visible spectrum, in 1666.
Whilst there are actually an infinite number of visible colours, Newton also showed that white light consists of 7 primary colours ie red, orange, yellow, green, blue, indigo and violet, in keeping with Aristotle’s seven classes of colour. These are not to be confused with what we understand as ‘primary colours’. That’s another discussion.
He also demonstrated that each colour in the spectrum is monochromatic meaning each consists of a single, unique wavelength that cannot be split into any further colours.
What is colour?
That’s light but what is colour?
When light hits an object, some is absorbed, and some is reflected. The reflected light is what we see and perceive as the colour of the object. The actual colour depends on the wavelength of the reflected light and how we perceive it.
Human perception
Humans are trichomats meaning we perceive three primary colours blue, green and red.
Each colour has a different energy level and wavelength. The retina in the human eye (the light sensitive layer of tissue at the back of the eye) can detect light between wavelengths of 400 nanometers (blue) to 700 nanometers (red). This range is better known as the visible spectrum.
The retina incorporates special cells called rods and cones. These see light reacting to light of different wavelengths. Different rods and cones react to different wavelengths or colours, of light. When light hits them, they react sending electrical signals to the brain via our optic nerves telling it what colours we are seeing.
Green sits in the middle of the visible spectrum at 555 nanometers.
This is where our visual perception is at its best. This means that green is the colour we see best both in terms of clarity and distance.
There is also some evidence to suggest that a combination of its nature and our visual acuity for green makes it more easily seen in smoky environments than many other colours. Technically, this is associated with a phenomenon known as ‘scattering’, the process by which light is deflected, refracted and absorbed by particles in the air changing the light’s direction, energy and even wavelength.
The ‘affordance’ or visibility of a green sign in differing conditions was apparently proven during the testing of alternative sign designs for competition in Japan when today’s ‘running man’ design was ultimately chosen – see below.
Human reaction
It is believed that the ability to perceive green was of significant, competitive advantage to primates in the past. In fact, the human species, which emerged in the forests and savannas of Africa 300k years ago, had a close biological relationship with the colour green and its meaning to our evolutionary advantage. Our eyes may have even evolved specifically to recognise the chlorophyll in plants unlike most mammals who are red-green colour blind.
It is also believed that due to our eyes being at the peak of their perception when, this may be why the colour green calms us down ie it takes less effort to perceive and hence our nervous system can relax through minimum strain being required.
A 2016 study found that living near green spaces can be linked to living longer and improved mental health. There are other benefits of course beyond the colour, the space and opportunity to socialise and how we react to nature but green is significant. The very word ‘green’ comes from the ancient Proto-Indo-European word ‘ghre’ meaning ‘grow’.
In fact, green is recommended for use in stressful environments such as hospitals, schools and offices. Historically, actors would even retire to ‘green rooms’ to calm their senses following their exposure to their stressful and brightly lit working environment.
Studies have shown that green offices create higher job satisfaction, and even that consumers spend more time shopping in stores that are green.
The tendency seems to be that we want to move towards green and away from red for example.
Green in signage
It is true that green is not used in emergency exit signage everywhere. North America and Canada for example, currently tend to use red (although in the US at least, this may be changing). However, it is true to say that most countries in the world adhere to international standards use green, either in text or as a background, many based upon the design created by Yukio Ota in the 1970’s (as seen in modern signage in the UK and signage legislation and something that the International Standards Organisation is currently urging the EC to revise the relevant directive to establish Ota’s design as the definitive version and no longer permit variants).
Conclusion
Whilst it has not been possible to prove that all the information conveyed here is behind green’s universal use, it seems much more likely than mere coincidence.
However, what is clear is that the reasoning, if only retrospectively, is sound.
It is easy for us to see. We can see it further away than any other colour, even in a smoky space. We like it and it makes us feel calm and safe.
Seems like a pretty good set of reasons to use it on a sign that is vital in an emergency situation and could save your life.
At Evaclite, we have worked hard to design products that have a consistent, evenly illuminated and ‘witness free’ (no inconsistencies or significant variations in colour, tone or opacity to compromise clarity or visibility – see patent number (GB2569053B), green and white legend that is compliant with the latest legislation).
It really does need to be green to be seen.