Both the internationalized European ECE Regulation 19[2] and North American SAE standard J583[3] permit selective yellow front fog lamps.

[4] However, selective yellow headlamps remain permitted throughout Europe on vehicles already so equipped, as well as in non-European locales such as Japan[5] and New Zealand.

These wavelengths are difficult for the human visual system to process properly, and they cause perceived dazzle and glare effects in rain, fog and snow.

[7] A research experiment done in the UK in 1968 using tungsten (non-halogen) lamps found that visual acuity is about 3% better with selective yellow headlamps than with white ones of equal intensity.

The colour swatch above is a desaturated approximation, created by taking the centroid of the standard selective yellow definition at (0.502, 0.477) and moving it towards the D65 white point, until it meets the sRGB gamut triangle at (0.478, 0.458).