My child has gotten ear infections three times since she was born. She is almost nine months old. The doctor keeps asking if she is around anyone who smokes. I told him that my ex-husband smokes. What kind of effect will this have on her, and what does it have to do with these infections?

S.

Imagine, if you will, that you just bought a house with truly miraculous plumbing. The pipes never become clogged. The inner lining of the pipes is composed of millions of tiny machines, each with an array of even tinier "feelers." These feelers constantly sweep back and forth. When something chunky threatens to clog the pipes, those cute little feelers just push that chunky thing right on through.

Now suppose your ex-husband shows up and decides to put some lye into your pipes -- you know, he's trying to be helpful. Unfortunately, unbeknownst to your ex, lye destroys those little feelers. Our sinuses, nasal cavities, middle ears (the air-filled space behind each eardrum) and eustachian tubes are, essentially, "miracle pipes." Some of the cells lining these spaces produce mucus, but most of the cells are coated with tiny feelers called cilia. In you, me and your daughter, these cilia constantly sweep the mucus out of our sinuses into our nasal cavities, out of our nasal cavities into our throats and out of our eustachian tubes into our throats. Then we swallow the stuff -- a whopping four cups (one liter) a day for the average healthy adult. Now, mucus is important stuff. All the crud we inhale (bacteria, viruses, mold spores, dirt, dust, ash, etc.) gets caught up in the mucus. We swallow it, and our stomachs destroy all the baddies.

Your ex-husband, thanks to his smoking, has destroyed most of his cilia, and now he's in the process of doing the same to your daughter's. If the cilia are injured, stasis results. In other words, the mucus just sits there. That gives the bacteria and viruses a chance to get a foothold. Result: There is a greater risk of cold, flu, sinusitis and ear infection.

By the way, three infections in nine months is not very bad -- certainly not bad enough for me to recommend ventilation tubes, but bad enough for me to recommend that you eliminate as many risk factors as possible. Here are the known risk factors: secondhand cigarette smoke, large daycare groups (six or more children), ceasing breastfeeding early and bottlefeeding in a horizontal position.