UV Light and Clothing

Introduction

Clothes can protect you from the harmful effects of ultraviolet radiation based on the type of fabric, the tightness of the weave, and the color. While sunscreens are rated with an SPF or sun protection factor, clothes are rated with a UPF or ultraviolet protection factor. A UPF factor indicates the amount of UV light that is absorbed by your clothes. For example, a shirt with a UPF factor of 50 will allow only 1/50th or 2% of the surrounding UV light to penetrate to your skin. Lightweight, light-colored, or loosely woven clothes have much lower UPF ratings than dark, tightly-woven clothes. While they might be uncomfortable on the beach, brand new jeans provide much better protection from the sun than a white t-shirt.

The ultraviolet band is broken into three types referred to as UVA, UVB, and UVC. The most harmful of these three, UVC light, is absorbed by the atmosphere and does not reach the Earth’s surface. UVB light is responsible for many skin problems, such as sunburns and several forms of skin cancer. UVA light is deep-penetrating and causes tanning, wrinkles, and some forms of skin cancer.

In this experiment, you will investigate the ability of your clothes to protect your skin from ultraviolet radiation. You will measure the levels of UVB light that can pass through fabrics, and you will compare fabric types and colors. In the second part of the experiment, you will get the fabrics wet, and again measure the amount of UVB light passing through.

Objectives

In this experiment, you will

• Use a UVB Sensor to measure UVB light.
• Determine the amount of UVB light allowed through various fabrics.
• Determine whether the UVB-blocking abilities of fabrics change when wet.