Why Is Most High-Visibility Safety Work Clothing Yellow?

On every construction site, engineering works location and the vast majority of places where dangerous work is carried out, the distinct look of high-visibility safety workwear is a ubiquitous sight.

It is typically a legal requirement to provide high visibility clothing suitable for a particular worksite whenever it is needed, and it should be fit for purpose, hard wearing and long-lasting.

It also often needs to be a standard shade of yellow with retro-reflective strips, but the reason why yellow became the most common standard colour for high visibility purposes is fascinating and does not originate with clothing.

The origins of yellow as a safety colour are believed to have started with Dr Frank Cyr, a professor at Columbia University and a conference he arranged to determine a group of safety standards for school buses in the United States.

As school buses pick up children at dawn and dusk, which can be particularly dark in certain parts of the country at certain times of the year, a bus that is set to be used by children needs to be highly visible in a wide range of conditions.

At the time, there were no standards for the colour of school transportation, which meant that certain colour vehicles were difficult to see, if not practically invisible in darker conditions, and any identifying text was impossible to make out, in line with the Purkinje Effect.

Dr Cyr, alongside other people at the conference that took place at Teachers College, discussed potential colour options and painted a range of coloured steps along the wall, looking for which ones were most visible when the lights were turned off.

Ultimately, the colour selected was a warm yellow shade, because it was easy to read black text off of it, it was very easy to make out at a distance and because it was currently not used for anything else, it would become associated with school buses.

It would take some time but a similar conclusion would be found around the world, although it was not initially a universal conclusion, and the shade of yellow most associated with safety would be quite different from the yellow-orange hue associated with school buses.

Indeed, the very first high visibility jackets were worn by track workers in Glasgow in 1964 and were fluorescent orange rather than the chartreuse yellow that is most commonly associated with high visibility.

Railway workers in the United Kingdom still use orange clothing to this day, but the use of chartreuse yellow was first considered a suitable shade for high-visibility purposes in the 1970s, after an attempt by ophthalmologist Stephen Solomon to change the colours of fire engines.

His logic, that the yellow-green shade was much more visible at night compared to red, was sound, but despite his evidence that it would be safer and avoid the potential Purkinje Effect issues that red vehicles look invisible in low light conditions, tradition endured and the fire engines stayed red.

However, it would be used for other equipment that needed to be easily visible as well as high-visibility jackets, and has been a standard for safety clothing since 1999.