PHILADELPHIA (CBS) — Are you a smoker or have you been a smoker for many years? If you are a smoker, you probably know what most of us are aware of — the fact that you are at much higher risk than everybody else for lung cancer.

But you are also at far greater risk for emphysema and chronic bronchitis—both grouped as chronic obstructive pulmonary disease or COPD.

With emphysema, the air sacs in your lungs are damaged and your body can’t get enough oxygen. With chronic bronchitis, the air passages to your lungs are inflamed and air has difficulty getting in and out.

At least 12 million US adults have the disease. It’s estimated that another 12 million people may have COPD but don’t know it. The simple act of taking a breath can become a major chore.

There are several symptoms. For instance, if your lips or fingernails turn blue or gray, it means there isn’t enough oxygen in your blood. You should go to the emergency room right away.

Reported By Dr. Brian McDonough, KYW Newsradio Medical Editor