Blood pressure measurement is one of the most fundamental tests any health professional performs. No physical exam would be complete without it.

Despite its importance, blood pressure measurement is frequently done incorrectly. That's the consensus of experts at a scientific meeting of the American Society of Hypertension (Journal of the American Medical Association, June 25).

The procedure may seem simple, but in reality it is more complex than most people (including physicians and nurses) realize. In one of the studies presented at the meeting, it was revealed that only about a quarter of specialized doctors and nurses took blood pressure readings properly.

The American Heart Association has published guidelines on how to measure blood pressure accurately, but only 8 percent of the health care providers participating in another study had read them. Here's a checklist for proper blood pressure measurement:

n Are you seated in a chair with back support so that your feet can rest on the floor?

n Are you allowed to sit quietly for five minutes before your blood pressure is measured?

n Is your arm resting on a table so that the cuff is the same height as your heart?

n Is the cuff the right size for your arm? Big arms need larger cuffs.

n Is the health care provider silent while taking your blood pressure? Engaging in conversation may be a friendly gesture, but talking can raise a person's blood pressure significantly.

If any of these guidelines is not followed, there is a good chance that the resulting blood pressure measurement will not be accurate. Clearly, this approach takes more time and care than the usual routine. Health care providers are not compensated for the extra time involved, despite the likelihood of error when they are rushed.

Because everyone assumes that blood pressure measurement is easy and does not require special training, the accuracy of results is rarely verified. The consequences of errors can be serious.

When the blood pressure reading is falsely low, patients and physicians may be lulled into an unwarranted sense of security. Needed treatment may not be given.

If the reading produced is higher than the patient's actual blood pressure, he may be subjected to unnecessary medication that can have side effects as well as financial costs. In fact, according to hypertension expert Clarence Grim, an extra 5 mm of mercury in diastolic reading between 85 and 90 would expose about 27 million Americans to a false diagnosis of hypertension and to the risks of medication.

We address proper blood pressure measurement, white-coat hypertension and nondrug approaches to lower blood pressure in our new Guide to Blood Pressure Treatment. Anyone who would like a copy, please send $3 in check or money order with a long (No. 10), stamped (59 cents), self-addressed envelope to: Graedons' People's Pharmacy, No. B-67, P.O. Box 52027, Durham, NC 27717-2027. It also can be downloaded for $2 from our Web site: www.peoplespharmacy.com.

Home measurement of blood pressure is one way to monitor progress. Only about one-third of people with hypertension control their blood pressure adequately, even though this is a critical step to help prevent heart attacks and strokes.

Q: You have written columns suggesting use of sunscreens with microparticles of zinc or titanium. I read that some scientists are concerned about nanoparticles found in products such as sunscreen. These particles are so tiny, they could get into places in our bodies that larger particles can't.

No one knows how dangerous this might be, but some experts suggest we exercise caution and avoid nanotechnology in products such as sunscreen. Shouldn't you warn people about the danger?

A: The Environmental Working Group is a collaborative group of scientists that first raised a red flag about nanoparticles in sunscreens. These extremely small particles of titanium and zinc compounds provide an effective way of blocking both UVA and UVB rays. Unlike the old white zinc oxide cream lifeguards used to smear on their noses, products containing nanoparticles appear transparent.

The researchers were suspicious about nanoparticles and expected that after reviewing all the safety data, they would recommend against using such products. They now have completed their analysis. It includes nearly 400 peer-reviewed studies. The conclusions they reached were quite different from those they anticipated:

"Repeated studies have shown that these ingredients do not penetrate healthy skin, indicating that consumers' exposures would be minimal." The scientists are critical of many other sunscreen ingredients and now suggest that consumers look for sunscreens with zinc or titanium to provide broad UV protection.

Q: I have been taking Toprol XL for about two years for high blood pressure, and my hair is getting so thin you can see through it. Is there any other medication that can replace Toprol XL that would not cause hair loss? Yes, I know: Vanity, thy name is woman. But I do hate losing my hair.

A: Beta blockers such as metoprolol (Lopressor, Toprol-XL) and atenolol (Tenormin, Tenoretic) may cause hair loss. Many cardiologists no longer consider beta blockers the best choice for first-line treatment of high blood pressure. Ask your doctor whether another medication might be appropriate for you.

Scores of other medications share this side effect. We are sending you our new Guide to Hair and Nail Care with a list of medications that may lead to hair loss. Anyone who would like a copy, please send $3 in check or money order with a long (No. 10), stamped (59 cents), self-addressed envelope to: Graedons' People's Pharmacy, No. H-31, P.O. Box 52027, Durham, NC 27717-2027. It also can be downloaded for $2 from our Web site: www.peoplespharmacy.com.

Q: Has anyone else wet the bed while taking Chantix? I had a very vivid dream that I had gotten out of bed, gone into the bathroom, sat down and urinated. Then I woke up and discovered that I had wet the bed.

I knew to expect nausea and weird dreams when I started taking the drug a month ago. Starting the second week, my anxiety and mood swings have gotten bad. The bed-wetting was the last straw. I stopped taking Chantix entirely. I'm not happy about that, because I really want to quit smoking.

A: We could find no scientific reports of bed-wetting linked to Chantix. This stop-smoking drug does cause vivid dreams and nightmares, which may contribute to this problem. Anyone who has experienced such a side effect can report it to www.peoplespharmacy.com or www.fda.gov/medwatch/.

"The People's Pharmacy with Joe and Terry Graedon" airs Saturday at 7 a.m. on WVTF (89.1) and at 4 p.m. Saturdays and Sundays on RADIO IQ (89.7).