Lung discomfort

This evening I spent about 15 minutes on a 10-year old treadmill that hadn't been used in years. It's been sitting by a window in the same spot for 4 years (in a moist climate), unused, gathering dust. After my brief workout I got off, and immediately felt a strange and unpleasant sensation in what feels like my left lung and to a much lesser degree in my right lung. It feels as if I breathed in cotton--pressured but not painful--and the air in the room is now very musty smelling. I am coughing occasionally.

It certainly seems like using the treadmill stirred up dust. My question is, do I need to refrain from using the machine again? Could I be breathing in anything other than dust that would be harmful--i.e. mold, etc?

FYI: I am middle aged and have very mild chronic asthma when I get respiratory illnesses. I exercise in a gym twice a week and walk once each weekend--so I do not think this is a result of the exercise itself. I have never posted a health question online before--I usually just shrug off minor physical concerns. But this really does feel and seem unhealthy.

Thank you.

[National Jewish Health]

You are right to suspect that you may have inhaled not just dust, but also mold, insect debris or even bacteria.  You would be wise to refrain from using the machine again, unless you can use it outdoors, while wearing a productive dust mask.  The outside use would be only to clear the machine of whatever foreign materials are in it and having done that, you could probably safely use it indoors.  But before using it outdoors I would suggest that you vacuum it carefully.

You are probably experiencing symptoms because of your pre-existing asthma.