How do light pollution filters work ... a high-pressure sodium streetlight radiates principally in yellow wavelengths. LPR ...

Typically, the doc explains, a yellow light is preset to run for a tenth of the posted speed limit. In cases where the speed limit is less than 30 mph, though, you can still expect a three-second ...

It absorbs red light and green light. A green filter only transmits green light. It absorbs red light and blue light. If yellow light shines at a red filter, red light passes through the filter.