DEAR DR. DONOHUE: I quit smoking one year ago. I had a cough when I was smoking, and I still have it, but it’s much milder. I saw a doctor, who tells me I have COPD. I do pant when I have to climb stairs or do chores around the house. The doctor put me on a medicine that I inhale. How is that helping me? What else can I do? — H.G.

 ANSWER: COPD, chronic obstructive pulmonary disease, is something that happens to many smokers. It happens to nonsmokers too, but not in the numbers that it strikes smokers. Emphysema and chronic bronchitis are the two COPD illnesses, and both usually develop together. Emphysema destroys the air sacs, the tiny, delicate, bubblelike structures through which oxygen passes into the blood. Chronic bronchitis is perpetual inflammation of the bronchi, the airways. Symptoms of COPD are breathlessness on exertion, cough, production of thick sputum and wheezing.

 The degree of COPD is best assessed through breathing tests — spirometry. Those tests guide the doctor in prescribing medicines and advising patients how they can best cope with COPD.

 Your inhaler medicine is one that expands the airways and reduces inflammation and mucus production. Often the inhaler contains both a bronchodilator (airway expander) and a cortisone drug (inflammation fighter). Taken as an inhalant, little cortisone gets into the blood, so its side effects are not great.

 Some simple tips make breathing easier for COPD patients. When you walk, bend slightly forward at the waist. That gives the lungs more room to expand, and it facilitates the action of the diaphragm, the chief breathing muscle. Practice pursed-lip breathing. Inhale through your nose and exhale through lips that are puckered, as they are put together when a person whistles. If you’re into precision, inhalation ought to take four seconds, and exhalation six. Pursed-lip breathing keeps the airways opened.

 The booklet on COPD explains this common illness and its treatments. Readers can obtain a copy by writing: Dr. Donohue — No. 601, Box 536475, Orlando, FL 32853-6475. Enclose a check or money order (no cash) for $4.75 U.S./$6 Can. with the recipient’s printed name and address. Please allow four weeks for delivery.

 DEAR DR. DONOHUE: Since I can’t go out in cold weather for sunlight and its production of vitamin D, will sunlight shining beautifully through my window have the same effect? Or is it better to take a vitamin D pill? — M.F.

 ANSWER: In summer or winter, window glass filters out ultraviolet-B rays, the sun rays that convert a precursor chemical in the skin into vitamin D. Therefore, the answer to your question is that you do not stimulate vitamin D production by sitting in front of a window through which sunlight shines.

 You live in the North. In winter, Northerners deplete their vitamin D stores because winter sun is less intense and because people are exposed to too little sunlight. It’s better to take a vitamin D supplement. The suggested dose is 1,000 IU. Don’t forget calcium. Vitamin D enhances calcium absorption.

 DEAR DR. DONOHUE: I am a 79-year-old lady who really likes molasses. I eat it every day. Is that too much sugar? Is it a good source of iron? — L.M.

 ANSWER: Molasses is the residue resulting from refining sugar cane and sugar beets in the preparation of table sugar. One tablespoon has 11.9 grams of sucrose (table sugar) and about 2 grams of glucose and fructose, two other sugars. That’s a goodly amount of sugar, but not an overwhelming amount.

 One tablespoon has close to 1 mg of iron. The daily iron requirement for postmenopausal women and for adult men is 8 mg. (It’s 18 mg for menstruating women.) Molasses provides some, but not all, of your daily iron need.

 I have never tasted molasses.

Dr. Donohue regrets that he is unable to answer individual letters, but he will incorporate them in his column whenever possible. Readers may write him or request an order form of available health newsletters at P.O. Box 536475, Orlando, FL 32853-6475. Readers may also order health newsletters from