DEAR DR. DONOHUE: I am a nurse, and I find myself constantly having to defend the medical profession by stating: “Pathogens (germs such as viruses) cause infections, not cold weather, snow or not wearing a coat.” People do have compelling arguments for weather influence on colds. For example, why do the majority of colds occur during winter? One argument is that people are crowded together in winter, but many people are indoors in summer when it’s so hot. Please give me more ammunition. – A.G.

You’re defending more than the medical profession. You’re defending the germ theory of infectious diseases, something that the great scientists – Pasteur and Koch – of the late 19th century proved beyond the shadow of a doubt. Stick with your campaign.

In honesty, there are gaps in our knowledge of the seasonality of infectious diseases, such as colds. However, there is no doubt that viruses cause them and that without a virus, colds don’t happen, regardless of weather conditions.

Experiments have been conducted with people sitting in cold, damp rooms without clothes. Those people had no more colds than did people who went about their everyday business, warm and with clothes on.

The cold and flu season actually starts in late August to mid-September, when children return to school. Children are easily infected by cold viruses; they bring the viruses home, and other family members disseminate them to the population at large. By mid-winter, cold spread is at its zenith.

If chilling and cold weather were responsible for colds, then people in tropical climates would never get them. They do, especially in their rainy season, when they take to the indoors as we do in wintertime.

Cold weather might have an effect on the catching of colds for another reason. Chilling causes blood vessels in the nose to constrict, and it decreases the production of mucus. That may make it easier for viruses to survive in people’s noses. That explanation is a bit of a stretch for me.

DEAR DR. DONOHUE: My father has a bad habit of sneezing and coughing into the air no matter where he is. He says it is useless to place a hand or a handkerchief over his mouth and nose, as that would only increase the pressure of the exiting cough or sneeze. My mother and I disagree with him and think he is spreading his germs into the air that we have to breathe. Whether he is 1 foot or 10 feet away from us, it makes no difference to him. He just lets it rip. What do you say? – O.M.

I say your dad is wrong.

He should cover his mouth and nose with a handkerchief or, better, a disposable tissue so he doesn’t release an aerosol of his germs into the air you and your mother breathe. Blocking a cough or a sneeze with the hand is not the best way to provide a barrier against spreading. His hand will be covered with viruses, and he can then spread the viruses to others through objects he touches, including you and your mother.

The “increase in air pressure” theory I cannot buy.

Tell your dad I said to cover his mouth and nose when he lets a cough or sneeze rip. It’s the hygienic thing to do. Currently, he represents a health hazard to his family.

DEAR DR. DONOHUE: What does potassium do? My friends talk about it all the time, and I feel left out of the conversation. Am I missing something important in my diet by my ignorance? – K.R.

Potassium is a mineral that’s busy doing a number of important jobs. It keeps the heart generating a heartbeat, it facilitates the transmission of nerve impulses and it makes muscle contractions possible.

Are your friends taking water pills – diuretics? Many such pills take potassium from the body, and users have to be sure they’re replacing lost potassium.

For people not on medicines that can deplete body potassium stores, it’s not hard to maintain normal potassium levels by eating a varied and balanced diet.

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

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