Keith Roach, M.D.

Dear Dr. Roach:

I decided to practice using an inhalation spirometer, partly because I have a daily productive cough (small amounts three to four times a day). I smoked a pack of filtered cigarettes a day from ages 17 to 29. I smoke marijuana now.

My scoliosis is quite complex and has taken over four inches off my height. But at age 75, I volunteer as a stable hand for six to eight hours a week, and they say that I’m the hardest working volunteer! I’m lean and fit.

I do three inhalation tests in a row, and it’s always 2,400 mL. Do I have chronic obstructive pulmonary disease, and should I report this to my primary care physician? He doesn’t know about my current marijuana consumption. — C.R.

Answer:

The diagnosis of chronic obstructive pulmonary disease is made based on symptoms (usually shortness of breath, cough, and sputum production); frequent exacerbations of breathing troubles; and abnormalities on breathing tests (or if there’s no other explanation). Your history of smoking tobacco and cannabis are compatible with a diagnosis of COPD, but you’d need pulmonary function testing in a lab.

The device that you have (which I think is an incentive spirometer) is very helpful for expanding their lungs, and it’s especially used after surgery. But the number doesn’t tell me a lot about your lung function.

The problem with COPD is that breathing gets obstructed, and although obstruction occurs with both inspiration and exhalation, it’s mostly when a person breathes out that symptoms occur. Some people have cough or sputum production without having any trouble breathing. This is most compatible with chronic bronchitis, which is one of the most common presentations of COPD; the other is emphysema.

Scoliosis, the curvature of the spine, can cause a completely different lung disease called restrictive disease. With restrictive diseases, it’s not airflow that’s the primary problem; it’s the lung volume. With severe chest wall deformities like scoliosis and kyphosis (when the spine is bent forward, sometimes called a “dowager’s hump”), the lungs can’t expand fully.

I’d certainly discuss your lung symptoms with your physician, who’ll consider sending you in for pulmonary function tests. These tests will tell you whether you have an obstructive disease like COPD or a restrictive disease. You should tell your doctor about your cannabis use; he should know and be professional about it.

If you do have COPD, I recommend against smoking cannabis. Although the evidence isn’t as strong that smoking cannabis causes COPD the way that smoking tobacco does, I still recommend against it in people with lung disease. If you want to use cannabis, take a gummy, since this doesn’t potentially harm your lungs the way that smoking does.

Dear Dr. Roach:

I’ve noticed that when I wipe the cap of my glass water bottle, there’s a dark gray or black material inside the cap after I’ve refilled it. Is this mold? Should I stop refilling the water bottle? — D.D.

Answer:

The cap of your glass water bottle is made from aluminum. When you open and close the cap, aluminum metal is exposed to air, where it reacts with oxygen to form aluminum oxide. This is the black material that you’re wiping off the cap. Aluminum oxide is inert and passes through the body, so you don’t need to worry about it.

Dr. Roach regrets that he is unable to answer individual letters, but will incorporate them in his column whenever possible. Readers may email questions to ToYourGoodHealth @med.cornell.edu. Copyright 2026 North America Syndicate Inc. All rights reserved.