Answer to Question #10233 Submitted to "Ask the Experts"

Category: Environmental and Background Radiation — Building and Construction Material

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


The radiation level on the ground floor in our house is between 0.06 to 0.28 µSv h-1 (the average for 24 hours is ± 0.155 µSv h-1). The reason for the relatively high radiation level is our ceramic tiles in this floor. I have a 2.5-year-old daughter and a one-year-old daughter who play on this floor many hours a day. In your opinion, is there any increased risk to my daughters with these measurements?


Some building materials (like some ceramics) are known to have slightly higher natural background radiation than others. The value you reported, 0.155 µSv h-1, while measurable, is still very low. Everyone in the world is exposed to natural background radiation, and the worldwide average is about 0.27 µSv h-1. Some areas of the world are lower than this average (like the value you reported), and some are much higher. For example, people living in Ramsar, Iran—one of the highest background radiation areas in the world—are exposed to dose rates as high as 15 µSv h-1 (about 100 times higher than the value you reported). No adverse health effects have been observed in the population of Ramsar (or any other high radiation background area). Your daughters are quite safe playing on your ceramic floor.

Brant Ulsh, PhD, CHP

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 16 April 2012. 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.