This is a very real threat.
Nearly anything that comes out of a spray can in your garage or shop and most clear finishes are combustible. Even an oily rag can used to wipe up a mess under the hood of your car can be dangerous to have around.
To prevent this, take all used rags outside to dry. NEVER leave them in a pile anywhere in your home or shop. I have gone a step further. I have a bucket in my shop half full of water. I have a lid on it. When I am finished with a rag, I drop it in there and let it soak. After about a month, I dump it and burn the rags. I live in a rural area and burning is legal here.
The worst chemicals I know of are;
Boiled linseed oil
Everything that ends in "-thane" like Sherwim Williams Rex-thane.
AND, if you find a mess in your barn, garage or shop that you don't recognise, it could very easily be a meth lab. The crank-heads here will set up a lab in ANY vacant building they can find. Typical warning signs are;
over the counter cold medicine packages
liquid fire containers, a plumbing declogging chemical
strong chemical odors, ammonia
If you find what you suspect could be a crank lab. Do not touch it.
Call your local police and stay away from it.
The chemicals used in that stuff can be very dangerous in many ways if they come in contact with each other. If someone comes out of your barn choking, do not give care to them too quickly. If they stop breathing, you better smell them for chemicals. Be careful not to make yourself sick or hurt.
It's a crazy world out there.