Anyone else getting really sick?

Lately I've been getting sick at an alarming rate. I'm a fairly young and healthy person, but in the last year I've been catching colds left and right. Back in April I caught a really bad cold and wound up in the hospital with pleurisy, and just a few weeks ago I caught another cold that has turned into a sinus infection. Am I just being paranoid or is it possible that this is due to something in the environment? I have a friend that works in a lab and he told me there is stuff in the air that we don't even know about yet.