Evaluation of UV-A and UV-B transmission through the windows of gas, hybrid, and electric vehicles
Authors: Axelson Grace E. , Constanza Jemima , Rezaee Ryan , Axelson Ava , Cenci Ally , Khan Ava , Weimann Rina , Ilyas Erum N. 
Published: January 2025

Abstract
UV-A exposure is a major risk factor for melanoma, nonmelanoma skin cancer, photoaging, and exacerbation of photodermatoses. Since people spend considerable time in cars daily, inadequate UV-A attenuation by car windows can significantly contribute to the onset or exacerbation of these skin diseases. Given recent market trends in the automobile industry and known impact of car windows on cumulative lifelong UV damage to the skin, there is a need to comparatively evaluate UV transmission across windows in electric vehicles (EV), hybrid vehicles (HV), and gas vehicles (GV) as well as variability based on year of manufacture and mileage to inform car manufacturers and consumers of the potential for UV exposure to the skin based on vehicle. To compare UV-A and UV-B transmission through EV, HV, and GV windows to evaluate differences in UV protection offered by various vehicle types. Comparative observational study that took place between June 10, 2024 and August 2, 2024. Outdoor setting with natural light exposure at car dealerships in Philadelphia, PA and New York, NY. 34 vehicles—15 gas vehicles (GV), 9 hybrid vehicles (HV), 10 electric vehicles (EV)—ranging from 2015 to 2025. Window status, with UV transmission measurements recorded with windows open and closed. UV-A and UV-B transmission through car windows was measured using UV transmission meters. The percent reduction in transmission was calculated. The front windshield and driver side window have statistically significant differences in UV-A attenuation across all vehicles with an average of 99.25% and 88.78% (p < 0.001), respectively. GV, HV, and EV all demonstrated significant differences in UV-A attenuation in most other vehicle windows compared to the front windshield. For GV, the front windshield, rear side windows (p = .176, p = .578) and back windshield (p = .457) blocked more UV-A than the front side windows. EV offered greater UV-A attenuation at the front and back windshield (p = .09) but not for any side windows, and HVs showed consistent differences in UV-A protection between the front windshield and all other windows. Domestic GV, trucks and luxury vehicles had no significant differences in UV-A attenuation across windows indicating reduced UV-A exposure for driver and passengers, whereas non-luxury vehicles had a notable difference in UV-A protection between the front windshield and all other windows. Regression analysis found mileage, not year of manufacture, to be a significant predictor of driver’s side UV-A attenuation, with more UV-A attenuation as vehicle mileage increases. Most vehicles evaluated offer effective UV-A and UV-B protection from the front windshield but lack sufficient UV-A protection for drivers nor consistently to other passengers with notable exceptions seen with domestic GV, trucks, and luxury vehicles. Mileage and not year of manufacture also contributed to additional UV-A attenuation. This underscores the importance of patient education on this known source for cumulative lifetime UV exposure and need for continued sun safety measures even while driving given potential UV-A impact on the skin.