ScienceWhy does the mucous during a cold changes its colour to yellow?To view this video please enable JavaScript, and consider upgrading to a web browser that supports HTML5 videoScience01/22/2015January 22, 2015Our viewer Ousman Ndure from The Gambia came up with this question. Here is Dr. Lekutat’s answer.https://p.dw.com/p/1EOqkAdvertisement