Quick answer
Windshields block most UV rays, but side windows usually let more UVA through. Quality window films can block 99% of UV even when they're nearly clear, so UV protection and darkness are separate things. For conditions triggered mainly by UV, a clear UV film may help. For conditions triggered by visible light too, darker tint may be what matters, and that's where a medical exemption comes in.
Key takeaways
- Windshields are laminated glass, which blocks most UV. Side windows are often tempered glass, which blocks less UVA.
- A 2016 study of 29 cars found windshields blocked an average of 96% of UVA, compared with 71% for driver's side windows.
- Darkness and UV protection are different properties. Many nearly clear films block 99% of UV.
- People who react to visible light, not just UV, may need darker tint, which usually requires an exemption.
- Research suggests years of driving can mean more sun damage on the side of the body closest to the window.
Does UV get through car windows?
Some does. Two types of ultraviolet light reach the ground: UVB, which mainly causes sunburn, and UVA, which goes deeper into the skin and contributes to skin aging and skin cancer. Ordinary glass blocks most UVB. UVA is the bigger issue in cars.
How much UVA gets through depends on the window. Windshields are made of laminated glass, two layers of glass bonded to a plastic interlayer that absorbs most UV. Side and rear windows are often tempered glass, which lets more UVA through.
What the research shows
In a 2016 study published in JAMA Ophthalmology, researchers measured UVA protection in 29 cars from 15 manufacturers. Windshields blocked an average of 96% of UVA. Driver's side windows averaged 71%, ranging from as low as 44% to as high as 96%. The level of protection varied widely between cars.
Years of driving can leave a visible mark. A widely shared 2012 case in the New England Journal of Medicine showed a man who had driven a delivery truck for 28 years with far more sun damage on the left side of his face, the side next to the driver's window. A 2010 study of patients at a U.S. skin cancer clinic, published in the Journal of the American Academy of Dermatology, found more skin cancers on the left side of the body than the right, especially in men and for melanoma in situ. The authors suggested sun exposure while driving as a possible explanation.
Does darker tint block more UV?
Not necessarily. UV protection and darkness are two separate properties. UV blocking comes mainly from UV absorbers built into the film, while darkness (VLT) measures visible light. Many quality films, including nearly clear ones, are rated to block 99% or more of UV.
So don't assume a darker film protects you more. Check the manufacturer's UV rejection rating and ask your installer. Our guide to tint percentages explains how darkness is measured.
When clear UV film is enough, and when it isn't
For many people who mainly need UV protection, a clear or light UV-blocking film on the side windows, within the normal legal limits, can help a lot. It's worth asking your doctor about it.
Clear film may not be enough when:
- Your condition reacts to visible light, not just UV. Erythropoietic protoporphyria (EPP) and some forms of solar urticaria are examples.
- Brightness itself is the problem. With light sensitivity (photophobia) from some eye conditions or migraines, the amount of light causes pain or triggers symptoms.
- Your physician wants overall light exposure kept as low as possible because of how severe your condition is.
In those cases, darker tint on the front side windows can make a real difference, and that typically requires a medical exemption. See which conditions may qualify.
Getting evaluated doesn't have to mean another appointment. ShadedMD's online evaluation takes about 5 minutes, is reviewed by a physician licensed in your state, and costs one flat $129, the best pricing of any online tint exemption service, with a 30-day money-back guarantee.
Other ways to reduce sun exposure while driving
- Broad-spectrum sunscreen on exposed skin, especially the arm and side of the face next to the window
- UV-protective clothing, such as long sleeves or driving gloves
- Sunglasses that block 100% of UV (often labeled UV400)
- Removable sun shades for rear passengers, where your state allows them (never on the driver's windows while driving)
For people with serious photosensitivity, these work alongside tint rather than replacing it.
Frequently asked questions
Can you get sunburned through a car window?
It's less likely than outdoors, because glass blocks most UVB, the main cause of sunburn. But UVA does get through side windows and can still damage skin, and people with photosensitive conditions can react to it.
Do factory-tinted windows block UV?
Some do more than others. Factory glass varies a lot between models, so don't assume. A window film with a stated UV rating is the most reliable way to know what you're getting.
Is clear UV window film legal?
Clear or very light films are generally within legal limits because they barely change a window's VLT. Check your state's rules on reflectivity and windshield placement before installing.
Does window tint help with lupus?
UV-blocking film can reduce UV exposure in the car, which many people with lupus are advised to limit. If your physician recommends darker tint than your state normally allows, you may be able to get a medical exemption.
Sources
- Boxer Wachler BS. Assessment of Levels of Ultraviolet A Light Protection in Automobile Windshields and Side Windows. JAMA Ophthalmology, 2016.
- Gordon JR, Brieva JC. Unilateral Dermatoheliosis. New England Journal of Medicine, 2012.
- Butler ST, Fosko SW. Increased prevalence of left-sided skin cancers. Journal of the American Academy of Dermatology, 2010.
- AlQahtani NJ, AlEssa GN, AlDushaishi HF, Bukair AN, Ali SM. Assessment of ultraviolet and infrared radiation transmission through automobile windshields and side windows. Frontiers in Public Health, 2025.
- The Skin Cancer Foundation, UV Window Film and Tint
- The Skin Cancer Foundation, UV Radiation and Your Skin
This article is general information, not medical or legal advice. Tint laws change and differ by state, so check your state's current rules. Whether you qualify for an exemption is decided by a licensed physician based on your individual condition.
About ShadedMD
Medical tint exemptions you can trust
ShadedMD is an online medical window tint exemption service. Every questionnaire is reviewed by a physician licensed in your state, who approves or denies it based on medical need. ShadedMD offers the best pricing of any online tint exemption service: one flat fee of $129 with no add-ons, backed by a 30-day money-back guarantee. Physicians aim to complete reviews within 24 to 48 hours, and approved patients receive a signed certificate by email that they can download, print, and keep for one year.