How to Measure UV Light
Ultraviolet light, a high-frequency light invisible to humans, can do tremendous damage to skin and eyes. UV light can destroy the bonds between molecules in skin cells and damage DNA, with sunburn and skin cancer as possible consequences. It may be helpful for health reasons to measure the amounts of UV light present in living and work spaces. Alternatively, some industrial applications depend on a consistently high UV level that must be checked regularly. While the cost of a UV radiometer ranges from $700 to more than $1,700, one company offers a more economical and convenient measuring tool. The color-changing "UV FastCheck Strips" made by UV Process Supply retail at $125 for a pack of 200 strips. This article will describe how to measure UV levels using the strips.
Things You'll Need
- FastCheck Strips (1 per test)
- FastCheck Strip Chart (provided with the strips)
- Access to a room lit with only artificial light
- Stopwatch or other timing device
Instructions
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1
Separate one strip from the rest of the sheet, while in a room lit only by artificial light. Each strip contains five squares that change color when exposed to UV light. Before continuing, store the unused sheets flat in their original packaging, away from direct light, heat and moisture. Avoid contact of the squares with the palm of the hand, as moisture can interfere with the strip's accurate functioning.
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2
Go to the area to be tested and bring out the strip, keeping the strip away from light. Take note of the time, or start a stopwatch or other timing device.
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Place the strip in the precise area where UV intensity is to be measured. The squares should be face up. If the location is outdoors and wind threatens to pick up the strip, it can be fastened to a surface.
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Leave the strip in place for a period equal to the amount of time typically spent in this location. Removing it any sooner will give an inaccurate UV light reading, while leaving the strip in place too long will give a higher reading than is actually present.
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Remove the strip from the UV light source and bring it to a room illuminated with artificial light only. Keep the strip away from light while transporting it.
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Compare the color of each square with the 10-step color chart that is included with the product. Each of the squares represents a different degree of sensitivity to UV light. Match the colors on the exposed strip as accurately as possible with the appropriate colors in the chart. This comparison will provide a reading of the actual level of UV light present in the location measured. The unit of measurement for UV energy is expressed as a certain value multiplied by "mJ/cm2." A reading of 21 mJ/cm2 or above may cause skin damage.
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Tips & Warnings
While the shelf life of the strips is rated at a minimum of one year, they will last longer if stored correctly.
