It's a common misconception that blue is the best color for def, when in fact it's actually green. Blue might be good for some things, but when it comes to def, green is better. Here's why:
Green has a higher wavelength than blue, meaning it can penetrate fog and smoke more effectively. This makes it ideal for use in situations where visibility is low, such as during a fire.
Green is also less likely to cause eye fatigue than blue light, making it easier to look at for long periods of time. This is important for people who need to scan large areas regularly, such as security guards or airport staff.
Finally, green tends to be more visible in general than blue. This means that people are more likely to see a green light from a distance, making it ideal for use as a signal or warning color.