Driving has been part of our daily lives, and we expect that we are more protected against the sun's ultraviolet-A (UV-A) rays inside our cars, but a new analysis shows that UV-A protection in the car side windows is not that effective as the front windshield.

UV-A radiation is known to have acute effects such as sun burn and tanning, which can last only for short-term and can be reversible. However, UV-A radiation can also have chronic effects that might be serious and life training including premature aging of the skin, suppression of the immune system, damage to the eyes, and skin cancer. UV-A, as opposed to UV-B, have long wavelength of light and has the ability to go through glass.

The analysis, published in the JAMA Ophthalmology, suggests that the lower UV-A protection of the car side windows might be the cause of the reported increased rates of cataract in left eyes and left-sided facial skin cancer.

For their analysis, the researchers measured the outside ambient UV-A radiation, along with UV-A radiation behind the front windshield and behind the driver's side window of all automobiles of 29 automobiles from 15 automobile manufacturers with years ranging from 1990 to 2014, with an average year of 2010.

The researchers then discovered that the UV-A blockage of the car side windows was 71 percent, significantly lower than the average UV-A blockage of the front windshield which was 96. They also found that only 4 out of the 29 automobiles being analyzed have a high level of UV-A blockage.

According to the report of Medical Daily, government regulations require windshield to be made with laminated glass to lessen potential injury when shattered. The combination of the laminated glass and extra-thick glass in front windshields provide extra protection against UV-A. However, side car windows are not required by the law to have laminated glass and are produce using thin glasses.

Tinting the car side window glass can lessen UV-A exposure, but this practice are considered to be illegal in some states. Researchers advise motorists to wear sunscreen above SPF 15 at least 30 minutes before driving.

The researchers also recommend automobile manufacturers to consider increasing the UV-A protection of car side windows.