I’m here with a public service announcement: Don’t leave aerosol cans baking in a car on a sweltering summer day unless you want to turn your vehicle into a DIY confetti cannon. Charlotte Allgood, an automotive technician and owner of the Glass Doctor company, shared a cautionary tale with Reader’s Digest. A car rolled into her shop with the back window completely shattered. The culprit? A hairspray can left to roast in the heat.

Now, we’ve all heard the urban legends about aerosol cans exploding in cars, right? There’s no shortage of viral photos showing cars with blown-out windows or torn-up seats and the remains of a metal can. Snopes fact-checked these claims and, while they couldn’t confirm the authenticity of the photos (thanks, Photoshop), they did confirm that aerosol cans can blow up if they get too hot. And honestly, that’s all the confirmation I need.

So what exactly is an “aerosol” can? It’s any spray can that’s pressurized, holding everything from hairspray to spray paint to bug spray. You know the type—it’s got a metal body, sealed tight with no twist-off top, and it delivers a continuous spray when you press the nozzle.

Here’s a simpler way to look at it: got a spray bottle of cleaner like Windex with a twist-off top? That’s not an aerosol can. What about a bug spray bottle where you have to pump the top every few seconds? Nope, not aerosol either.

Aerosol cans actually pack two things inside: the product itself, like hairspray or WD-40, and a propellant, which is a liquified gas under serious pressure. When you press the nozzle, that gas forces the product out. It’s this compressed gas that can cause the can to explode if it gets too hot. Oh, and as a bonus bummer, some of these propellants also damage the ozone layer. So, avoiding aerosol cans whenever possible might not just save your car’s windows—it could save the planet, too.