You know the feeling. You've been out running errands on a hot summer afternoon, and as soon as you open the door of your car, you are hit in the face with a wall of suffocating heat. The steering wheel is hot, the seatbelt buckle could sear a steer, and sitting on a black leather seat is like a punishment. If this sounds familiar, there might be an easy fix you aren’t using, and the research backs it up.
A study, ‘Parked cars get dangerously hot, even on cool days, Stanford study finds,’ published by researchers at the Stanford University School of Medicine, discovered that the temperature inside a parked car can increase by an average of 40 degrees Fahrenheit within an hour, no matter the temperature outside. According to the Stanford study, about 80 percent of that rise occurs in the first 30 minutes, meaning your car heats up to dangerous temperatures much faster than most people think.
Why your parked car turns into an oven
The reason is the greenhouse effect. Sunlight passes through your car’s glass, warming everything inside the car, the dashboard, the seats, the trapped air, and the heat has nowhere to go. In the Stanford research, lead author Dr. Catherine McLaren, a clinical instructor in emergency medicine, said there are instances of children dying on days as cool as 70°F because it’s not the outside temperature that matters, but whether the sun is out. The windscreen is the largest piece of glass on most cars, the largest portal for all that solar energy, which is exactly why blocking it matters so much.
What a sunshade really does and how much it helps
A windscreen sunshade reflects incoming sunlight out through the glass before it has a chance to bake your interior. It doesn't actively cool the air in your car, but it prevents the main source of heat from doing damage in the first place.
