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Activity Number 22 - UV And Clothing


To Demonstrate The Effectiveness Of A Variety Of Fabrics On Reducing UV.


  • UV meter
  • pencil and pad
  • at least five different fabric swatches or items of clothing in a variety of weaves, colours, and weights.

Suggestions: bathing suit, white cotton T-shirt, dark coloured T-shirt, polyester shirt, jeans, mesh T-shirt.


  1. Carefully identify each clothing sample (numbered adhesive labels and a legend sheet are recommended).
  2. Take a UV reading with the UV meter in direct sunlight and record the value.
  3. Remain in direct sunlight. Place the clothing samples, one at a time, on the UV meter over the black sensor button. Make sure that the button is completely covered. Do not touch the sensor with your fingers.
  4. Wait a minute for the UV meter to adjust and record the new reading. Change the clothing sample. Record all measurements on your sheet.
  5. Calculate the percentage of UV transmitted through each type of clothing, compared to the full sun reading.

    UV transmitted (%) = (reading under clothing ÷ full sun reading) x 100 percent
    UV reduction (%) = 100 percent - UV transmitted


Compare the amount of UV that penetrated various fabrics depending on the type, weave, colour and weight. As with shade, all fabrics are not created equal when it comes to UV protection.


In general, denim and polyester protect better than cotton; tight weaves, better than loose; dark colours, better than white; and heavy fabrics, better than light.

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