Letters from the December 18 & 25, 2004, issue of Science News

Think fast

“Car deaths rise days after terror attacks” (SN: 10/9/04, p. 237: Car deaths rise days after terror attacks) mentions that the traffic volume was reduced following the attacks, yet fails to mention another likely factor in the increased deaths: Less traffic usually results in higher average speeds.

Del Dietrich
San Jose, Calif.

Our sun, the healer

I found your articles on vitamin D very interesting (“Vitamin Boost,” SN: 10/9/04, p. 232: Vitamin Boost; “Vitamin D: What’s Enough?” SN: 10/16/04, p. 248: Vitamin D: What’s Enough?). My question now is whether the rays received in a tanning bed can cause the skin to manufacture vitamin D.

Wendy Wade
Kalamazoo, Mich.

Ultraviolet–B radiation triggers the skin to produce vitamin D, whether those rays come from the sun or a lamp. However, not all tanning salons use lamps that emit UV-B rays as well as UV-A wavelengths.—J. Raloff

Two thoughts on vitamin D: Are treatments for seasonal affective mood disorders, involving shining bright lights on the skin, effective simply because they stimulate the production of vitamin D? Does exposure to sunlight affect blood-cholesterol levels?

Steve Palmer
Plainfield, N.J.

Could the lack of vitamin D be a cause of the “death in the dark months” of elderly people? The rise of depression in the winter months could be accounted for, as well, and perhaps treated very simply by adding the vitamin to our diets. Follow up, please.

Karl L. Roesch
Arlee, Mont.

Ending the year right

I sincerely thank you for the informative articles you make available. My family and I look forward to Science News, and we always share the knowledge acquired with our friends. We view your publication as a national resource.

R.N. Molina
San Diego, Calif.

My wife has been giving me a subscription to Science News for many years, and I still read each edition in its entirety. What I love about the Web site is the ability to find an article I have read previously, reread the article, and e-mail it to someone with whom I have been discussing the subject. I encourage everyone who has any interest in science to get your publication. Keep up the good work!

Everett Clary
Friday Harbor, Wash.