Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

I Do car windows and windshields block ultraviolet light?

  1. Jul 17, 2018 #1
    I'm curious if car windshields / windows block UV (ultraviolet) light, the one from either the sun, or UV flashlights, like the Convoy S2+ Nichia 365nm.
  2. jcsd
  3. Jul 17, 2018 #2


    Staff: Mentor

    It is not an all/none situation, it is a question of how much and which frequencies. I found this study.

  4. Jul 17, 2018 #3
  5. Jul 22, 2018 #4
    I bought a new car in February, and as the seasons changed I noticed it wasn't nearly as hot inside the car left in the sunshine as my previous car. I did some asking around and found out that the major difference is in the chemical makeup of the glass itself. So not only does it depend on the frequencies, it also depends on the make, model and age of the car.
  6. Jul 24, 2018 #5
    Was it definitely the glass, or was it a coating on the glass?
    I know NSG make vehicle glass with infrared reflective coating, which helps to keep the car cooler.
  7. Jul 24, 2018 #6
    Yeah probably it was some anti-IR coating or higher glass thickness, because as far as I know UV does not cause heat, it's the IR mainly. Also, smaller windows or better bodywork insulation or better AC cooling system can lead you to think that.

    If you mention the make, model and year of both cars, would be a good piece of information.
  8. Jul 27, 2018 #7
    Could be a coating, don't know. It's definitely cooler inside when the car is left in the sunlight. 2018 Civic SI.
  9. Jul 28, 2018 #8


    User Avatar
    Science Advisor
    Gold Member

    Not so. Read about the greenhouse effect.
  10. Aug 4, 2018 #9
    Ok did the proper tests on my car. It's a Volkswagen Golf 4, and this is the additional hardware that I used:
    The results are as follow:
    1. Direct sunlight on the UVM30A sensor: displays index 6-7.
    2. Direct sunlight all around the car and UVM30A on the other side of the windows and windshields: index 0.
    3. Nichia 365nm flashlight to UVM30A sensor, with windows in the middle, only the front windshield displays index 0. All other windows from the sides and the back display very high index values, so apparently they don't filter the 365nm wavelenght.
    Last edited: Aug 4, 2018
  11. Aug 5, 2018 #10


    User Avatar
    Science Advisor
    Gold Member

    Very nice experiment that matches with manufacturing practice. Most car windows are made of tempered glass, which is just glass that is specially heat treated. The law requires windshields, however, to be made of laminate which has a plastic film sandwiched between two glass sheets. The plastic keeps the glass from shattering, and also absorbs UV light.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?