I'm still writing our latest NerdyBook: "Just the tips, man for the Environment" and I'm on the "Awful Automobiles" chapter. I just wrote a tip about car air conditioning that I have to share. To be honest, prior to researching this topic, I thought all AC was bad. It's amazing how a fact like "Car air conditioners emit chlorofluorocarbons (CFCs) which contribute to the depletion of the ozone layer" stick with you - for life.

Little did I know, this hasn't been true for 10 years. (Where was I when this fact came out?) According to the EPA's web site,

In vehicles made before 1992, the AC system uses CFC-12. In vehicles made in 1992, 1993, or 1994, the AC system might use CFC-12. If your vehicle was made in 1995 or later, it does not use CFC-12. By 1995, all vehicle manufacturers were using the new, ozone-safe HFC-134a refrigerant in every vehicle made.

So how do you know if your older car's AC system uses CFC-12? Again, according to the EPA,

You can find a refrigerant identification label on the air conditioning compressor or elsewhere inside the engine compartment. You can also ask your service technician or vehicle manufacturer.

The next fact that startled me, and this came from several sites including WorldChanging's web site,

At city speeds it's best to just roll down the windows; at highway speeds AC is better, but using flow-through ventilation instead of the actual AC is best.

Of course, sitting at home and not driving your car emits no CFCs and uses no fuel. Zilch.