As we spend more time in the car, it is important to know how to protect your baby from damaging sun exposure that can penetrate through car windows.

Types of UV Radiation

Ultraviolet (UV) radiation is part of the invisible electromagnetic (light) spectrum that reaches the earth from the sun.  There are three types of UV radiation:

• UVC is filtered out by the ozone layer and does not reach the earth’s surface.  This type is not a concern.  
• UVB causes sunburn and plays a major role in skin cancer and skin aging. Fortunately, UVB rays are unable to penetrate through most types of glass.   
• UVA can penetrate through glass, causing skin damage that is not as obvious as a sunburn. According to the Skin Cancer Foundation, UVA rays account for up to 95 percent of the UV radiation reaching the Earth’s surface and are 30 to 50 times more common. In addition, UVA affects the skin more deeply than UVB. Research over the past couple decades shows that UVA can damage skin cells in the basal layer of the epidermis (outermost layer of the skin) where most skin cancers are found. Therefore, UVA contributes to and may even cause skin cancer.

Types of Window Glass

The type of glass and the coating on it will affect the amount of UVA that passes though. While all types of glass block UVB, their ability to block UVA varies.  The three types of glass include:

• Ordinary (clear)—allows up to 75 percent of UVA to pass through.
• Reflective (can see in one direction better than the other)—allows 25 to 50 percent to pass through.
• Tinted—allows 25 to 50 percent to pass through.

Most cars today have windshields made of laminated glass that blocks all of UVB and most of UVA. However, the side and rear windows are usually made from non-laminated glass and let more UVA through.

Factors that can Influence Amount of Sun Exposure

There are several factors that can affect the amount of sun exposure your child receives while riding in the car, including:

• Length of time in the car.
• Weather conditions.
• Time of day and year—the sun tends to be strongest between10am and 4pm.
• Whether you are driving into or away from the sun.
• How close an individual is sitting to a window.
• Where in the car an individual is sitting—infants in rear-facing car seats are being exposed to the sun coming through both the side and rear windows

How to Protect Your Child

• Add a tinted, UV-protective film to your car’s side and rear windows to reduce UVA penetration.  Make sure to comply with federal regulations on the amount of tinting allowed.
• Dress your baby in sun-protective clothing with UPF (ultraviolet protection factor). This is especially important for newborns, as not only  have delicate skin, but they also cannot have suncreen applied (not until your baby is 6 months old).
• Choose clothing with good sun protective qualities such as bright or dark colors (since they reflect more UV radiation than light-colored clothing) and tightly woven, loose-fitting clothes that provide a good barrier between a child’s skin and the sun.  A good way to test if a fabric  has a good UPF is to hold it up to the light - if you can see through it then light can pass through and onto your baby's skin.
• Use a dark colored, tightly woven baby cap to protect your baby's head from the sun. Do not use hats that tie up under the chin as they can pose a choking hazard.
• Choose a car seat with a built in shade canopy - preferably one that can move depending on the direction of the sun.
• Install window shades. 
• Use a car seat shade that fits over the whole car seat.

Remember - Never leave your baby alone in the car.

By Sandi Schwartz - Science writer and mom.

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