How can I tell whether the windshield and side windows of a car are UV protecting?

I know I could use a portable UV radiometer/sensor, assuming I can place the car under the sun. What are other solutions?

2 Answers 2


Use a UV ray light. Keep phosphorus material inside see if it lights up.

Light on the outside, glowing material inside, through the window you hope it does not light up.

  • 1
    Canadian 20 dollar bill lights up under a UV light. Jun 3, 2017 at 17:08
  • Thanks. Aside from the bill, any idea where I could get some cheap phosphorus material? Jun 3, 2017 at 18:01
  • 1
    @FranckDernoncourt anything washed in "whiter than white" washing powder fluoresces under UV.
    – Chenmunka
    Jun 3, 2017 at 18:11
  • 1
    You get either 'Tonic Water' or 'Green Anti-Freeze' (old batches used to glow under black UV). Jun 3, 2017 at 18:22
  • 1
    Most colored price stickers are UV-reactive, as are safety vests, brightly-colored childrens' toys, some white paper, and various other things. Glow-in-the-dark materials really light up under UV.
    – Mark
    Jun 4, 2017 at 0:01

According to this website there are two different types of UV radiation, UVA (longwave) and UVB (shortwave). Glass in and of itself absorbs the UVB light. The front windshield is treated to absorb UVA light as well. The sides and back window are not treated to absorb UVA light and will allow it to pass through. Unless UVA absorbing tint has been applied to your side/rear windows, the light will pass through.

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  • thanks! Is there any way to tell whether UVA absorbing tint has been applied to the side/rear windows? Jun 3, 2017 at 16:50
  • @FranckDernoncourt - You can tell on the glass itself. Look at the edge as the tint will not go all the way to the edge. There will be a gap and you'll be able to see it. It's applied to the inside of the window. Jun 3, 2017 at 17:46

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