What your mucus says about your health

It's peak cold and flu season, and mucus is making many of our lives miserable. But despite being a little icky, phlegm gets a bad rap. This germ-fighting goo contains cells and chemical compounds that help us power through a cold. You can also think of mucus as a traffic light for your health - what turns up in our used tissues can be a useful clue about the inner workings of our immune systems. Reactions decodes the mysteries of mucus in its latest video.

Reactions is a video series produced by the American Chemical Society and PBS Digital Studios.

The American Chemical Society is a nonprofit organization chartered by the U.S. Congress. With nearly 157,000 members, ACS is the world's largest scientific society and a global leader in providing access to chemistry-related research through its multiple databases, peer-reviewed journals and scientific conferences. The American Chemical Society does not conduct research, but publishes and publicizes peer-reviewed scientific studies. Its main offices are in Washington, D.C., and Columbus, Ohio.