Don't run an engine in a garage or anywhere else without proper ventilation EVER! Carbon monoxide is poisonous; it is absorbed by the body 400 times faster than oxygen; it takes a long time to leave the human body and you can build up a deadly supply of it in your system by simply breathing in a little every day. YOU may not realize you are slowly poisoning yourself. Always use power vents, windows, fans or open the garage doors.Don't work around moving parts while wearing a necktie or other loose clothing. Short sleeves are much safer than long, loose sleeves. Hard-toed shoes with neoprene soles protect your toes and give a better grip on slippery surfaces. Jewelry such as rings, necklaces and watches or large belt buckles are not safe working around a vehicle. Long hair should be secured under a hat or cap.Don't use your pockets as toolboxes. A fall or bump can drive a screwdriver deep into your body. Even a wiping cloth hanging from the back pocket can wrap around a spinning shaft or fan.Don't smoke at any time when working on the vehicle, especially around gasoline, cleaning solvent or other flammable material.Don't smoke when working around the battery. Batteries give off explosive hydrogen gas at some level even when not being charged.Don't use gasoline to wash your hands; there are excellent soaps available. Even unleaded gasoline contains benzene, a known carcinogen, which is absorbed through the skin. Gasoline also removes all the natural oils from the skin so that bone dry hands will suck up oil and grease.Don't service the air conditioning system unless you are properly trained, certified and equipped with the necessary tools. If necessary to discharge the refrigerant system, a recovery/recycling station must be used. The refrigerant, R-12, is extremely cold and when exposed to the air, will instantly freeze any surface it comes in contact with, including your eyes. Although the refrigerant is normally non-toxic, R-12 becomes a deadly poisonous gas in the presence of an open flame. One good whiff of the vapors from burning refrigerant can be fatal.