A sunshade is a reflective shield that can protect the interior of a car from the adverse and sometimes lethal effects of the sun’s UV radiation. According to NOAA’s National Weather Service, extreme heat, direct sunlight, and closed windows can increase interior temperatures to nearly 200°F in just 15 minutes. Every year children, adults, and pets die from hyperthermia, a condition that occurs when the body absorbs more heat than it can dissipate.
On a sunny day, an automobile experiences what is commonly called “the greenhouse effect.” Sunlight passes through automobile windows as shortwave radiation; however, since most surfaces inside a car aren’t reflective, they absorb most of the radiant energy from sun. The hot dashboard, steering wheel, seats, etc heat the interior air though conduction and convection; but the same glass that allowed the transmission of visible light, blocks infrared thermal radiation from escaping. If the windows are up, air is unable to flow amplifying the heat-trapping effect.
UV radiation also causes noticeable damage to the interior in as little as 2-3 years. Cracks in vinyl and leather, faded upholstery, and dull plastic parts are just some of the adverse side effects.