Answer to Question #12178 Submitted to "Ask the Experts"

Category: Ultraviolet Radiation

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


I want to build a bacteria-killing filter for a pool and fish pond. Would acrylic plastic about 1 centimeter (cm) thick prevent ultraviolet-C (UV-C) radiation from passing through? The alternative is probably quartz glass, but the advantage of acrylic or Plexiglas is that it is easier to work with.


UV-C light is a very energetic form of light that is not visible to the human eye. Based on our evaluation, UV-C light which is used for germicidal processes will not penetrate standard acrylic plastic sheets, so they will not work for your proposed application.

UV light, a form of energy, is defined as light having wavelengths between 100 nanometers (nm, 1 billionth of a meter in length) and 400 nm. (For reference, the human eye is sensitive to light between about 400 nm [blue] and 700 nm [red]). UV light is further divided into UV-A, UV-B, and UV-C light. The wavelength of UV-C is 100 to 290 nm. In general, UV-C does not penetrate the earth's atmosphere (please refer to Ask The Expert Question 12082.

The ability of UV-C light to penetrate materials will depend on the chemical composition of the materials. Most acrylic plastics will allow light of wavelength greater than 375 nm to pass through the material, but they will not allow UV-C wavelengths (100–290 nm) to pass through. Even very thin acrylic sheets of less than 5 millimeters (mm) do not let UV-C light penetrate. Therefore, you will not be able to use standard acrylic plastic for your application.

Because the ability of UV light to penetrate acrylic plastic is dependent on the chemical formulation, you may be able to find plastic sheets that will allow the UV-C to penetrate. If you would like a more technical discussion on the transmission of light through acrylic plastics, please go to the Cole-Parmer website.

Paul A. Charp, PhD

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 9 October 2017. 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.