every 1/2 hour i have to take in a deep breath like i'm out of air. why is this?

jody,

Thanks for your question.  It sounds as though you are taking a "sigh" every half hour.  I have seen patients with this complaint and in a couple of patients, it was determined that they had a mild form of asthma.  Their symptoms would increase in hot, humid weather.   

Sigh is a natural maneuver that the body makes every once in a while.  It helps boost oxygen levels and clear carbon dioxide.  It also keeps the lungs at a fully inflated status (a sigh's most important function).

My suggestion is to discuss this with your primary care physician or possibly seek the opinion of a pulmonary specialist.  You should have full pulmonary breathing tests, as well as the history and physical performed by the doctor.  These would be the best first steps to persue.  They would be able to direct you further should these tests be normal.

Best wishes.

Martin Cane, M.D.