Lather Up for the Drive

Skin cancer risks from ultraviolet light exposure through car windows

/ Author:  / Reviewed by: Robert Carlson, M.D

(RxWiki News) Anyone who’s had a bad sunburn knows to use sunscreen before heading outside. They may also want to start using sun protection while driving in a car. Car windows can let up to 80 percent of UV rays inside.

A recent study asked patients at a skin cancer clinic about their use of sunscreen while driving.

Researchers found that most of the patients thought car windows protected them from the sun. In reality, only dark-tinted windows can significantly reduce ultraviolet light from entering the car.

"Use sunscreen while driving, too."

Dennis P. Kin, MD, from the School of Medicine at Stony Brook University in New York, led a group of colleagues to investigate the use of sunscreen while driving.

The researchers estimated that people spend on average between 80 and 100 minutes driving in a car every day. “Because such a large portion of a person’s cumulative (total) sun exposure occurs while in a vehicle, automobile-related ultraviolet A (UVA) light exposure is a considerable health concern,” the authors said.

For the study, 225 people who had been treated at a Mohs micrographic surgery clinic were surveyed about the use of sunscreen while driving in a car.

Mohs micrographic surgery is technique that involves examining and removing each individual tissue layer at skin cancer sites so that the surgeon removes only cancerous cells and leaves healthy skin cells alone. The process is very time consuming, but also very effective at removing skin cancer.

Survey participants consisted of men and women with either melanoma type skin cancer, non-melanoma type skin cancer (basal or squamous cell carcinoma) or both.

When asked about using sunscreen while driving:

  • 67 percent of patients said they didn’t think they needed sunscreen when the windows were closed
  • 51 percent of patients said they didn’t think they needed sunscreen when the windows were open
  • 40 percent said they thought they were protected from sun damage when the windows were closed
  • 14 percent said they thought they were protected from sun damage when the windows were open
  • 53 percent of patients said they thought tinted windows helped to protect them from sun damage

An average of 52 percent of patients reported wearing sunscreen for general daily use, but only 27 percent reported wearing any sunscreen while in the car. Most of the participants said they were unaware that they needed to wear sunscreen while driving, especially if the windows were closed.

Based on previous research, the authors estimated the average untinted car window allows 62 to 80 percent of UVA light to enter the car, while dark-tinted windows allow an average of 1 to 11 percent of UVA light through. Windshields have a special lamination that allows only about 2 percent of UVA light into the car.

The shoulder, arm and hand exposed to the side window are at the greatest risk for UVA sunlight exposure. 

The researchers found more non-melanoma skin cancers on left shoulders, arms, hands and necks than on the right side of the body. The authors concluded that the left-sided frequency of skin cancer was due to driving without sunscreen.

This study was published in February in the Journal of the American Academy of Dermatology.

No outside funding sources were used for this study. No conflicts of interest were declared.

Reviewed by: 
Review Date: 
February 18, 2013
Last Updated:
August 16, 2013