Probably because its bright

I suppose that Yellow color has maximal visibility and immediately catches attention on danger

Thanks dr. Mutasem Z. Bani-Fwaz ,dr. Marianne Levon Shahsuvaryan and dr. Abiodun Olusola Omotayo for answer

Nice comments by Dr.Mutasem.

Because the Yellow is one of the most sensitive colors of the eye so it is used to warn in the edges of sidewalks and paint trees to be clear at night.

Regards

Well , I did not know why that color !!!!

Yellow has always been known to be an energetic and cheerful colour. In colour psychology, this symbolises positive emotions such as fun, youth, optimism, confidence, and happiness. Yellow inspires thinking and stimulates learning.

In order for you to understand why yellow became the official colour for safety, you have to know how our eyes and brain perceive this colour.

When light hits a certain object, the object absorbs some of it, while some are reflected. This reflected light enters our eyes and reaches specialised receptors called cones. These cones get excited as the light hits them and they send signals to the brain. Different light wavelengths stimulate specific combination of cones, making us perceive the different colours. The red and green cones in our retina are highly sensitive to light.

When we see yellow, both of these types of cones are excited to almost peak intensity. In addition to that, other parts of the eye reduce sensitivity to violet and blue light, making yellow appear to be the brightest among all the colours in the spectrum. Another unique characteristic of yellow is that even most colour-blind individuals can see it.

Using yellow as a background for a black text provides maximum visibility and readability whether it’s day or night. This makes yellow the perfect colour for safety signs.

Nice question!

awesome question

The use of yellow was standardized at Oak Ridge National Lab in early 1948. At that time, Bill Ray and George Warlick, both working for K.Z. Morgan, were given the task of coming up with a more suitable warning sign, a blue background being too unacceptable. Ray traveled to Berkeley and picked up a set of their signs. Back in Oak Ridge, Ray and Warlick had their graphics people cut out the magenta symbols and staple them on cards of different colors. Outdoors, and at a distance of 20 feet, a committee selected the magenta on yellow as the best combination.

https://www.orau.org/ptp/articlesstories/radwarnsymbstory.htm

Yellow