Answer to Question #11747 Submitted to "Ask the Experts"

Category: Pregnancy and Radiation — Flying

The following question was answered by an expert in the appropriate field:


I would like to inquire if traveling during the first trimester would expose my baby to high ultraviolet (UV) radiation levels at high elevations. I will fly around 11,560 kilometers (km) or 14 hours (approximate flight duration from Europe to Asia).


While UV radiation levels are higher with increasing elevation, your baby will not be exposed at all. Ultraviolet radiation exposure does increase with elevation—about 9–20% per km of elevation—but the depth of penetration of UV photons does not change.

UV light is unlikely to penetrate any deeper than the thickness of skin (1–4 millimeters [mm]). Penetration into the skin is at the higher end for white skin and decreases for darker skin.

During the first trimester, the baby is "shielded" by approximately 80 mm of tissue. UV light cannot penetrate that far.

Kelly Classic
Certified Medical Health Physicist

Anderson RR, Parrish JA. The optics of human skin. J Inv Derm 77:13–19; 1981.

Ask the Experts is posting answers using only SI (the International System of Units) in accordance with international practice. To convert these to traditional units we have prepared a conversion table. You can also view a diagram to help put the radiation information presented in this question and answer in perspective. Explanations of radiation terms can be found here.
Answer posted on 21 September 2016. The information posted on this web page is intended as general reference information only. Specific facts and circumstances may affect the applicability of concepts, materials, and information described herein. The information provided is not a substitute for professional advice and should not be relied upon in the absence of such professional advice. To the best of our knowledge, answers are correct at the time they are posted. Be advised that over time, requirements could change, new data could be made available, and Internet links could change, affecting the correctness of the answers. Answers are the professional opinions of the expert responding to each question; they do not necessarily represent the position of the Health Physics Society.