Purple street lights are primarily caused by a manufacturing defect in LED streetlights, specifically the degradation or delamination of the phosphor- silicone layer that normally coats the blue LED chip to produce white light. When this phosphor layer deteriorates, the light emitted shifts from white to a distinct purple or blue hue. This issue began appearing widely in many cities across the United States, Canada, and even parts of Europe around 2021 and is linked to faulty or low-quality LED manufacturing and heat or vibration effects over time. This shift to purple lighting is unintentional and results from failing LED components rather than a deliberate design choice. It can create safety concerns because the altered color makes it harder for drivers and pedestrians to see details and differentiate colors correctly at night, potentially posing hazards. As a result, many municipalities are replacing the affected lights with newer, properly functioning LED fixtures.
In short, purple street lights appear due to a technical failure in LED phosphor coatings, not for aesthetic or environmental reasons.
