Dear Tom and Ray:

Our 1995 Chevy Cavalier was parked on the street where we live, about eight blocks from the World Trade Center, on Sept. 11. The car was covered with a light coating of dust -- but not inundated, like the cars right next to the WTC. We've barely driven the car since then. We're trying to decide whether to have the car's engine "detailed" to remove any contaminants that might be in the ventilation system. Does that make sense to you? -- Cindy

TOM: Well, the first thing you should do is call your insurance company. If you were close enough to the disaster to have debris on your car, a professional cleanup might be covered under your comprehensive auto policy, and that would be the best thing to do.

RAY: But after they weasel out of helping you, you'll have two separate issues to deal with.

TOM: One issue is the engine. And you don't have to worry too much about that.

RAY: The engine has an air filter to prevent airborne contaminants from getting inside the combustion chamber. So changing the air filter and wiping out the snorkel with a disposable wet cloth (and as much of the rest of the engine compartment as you can reach) should be all you need to do to protect the engine. And if a little bit of dust happens to get in there, it'll just get combusted and sent out your tailpipe.

TOM: But the second -- and more important -- issue is the ventilation system. The passenger compartment's ventilation system is probably also covered with WTC dust. And as you probably know, there have been conflicting reports about how much asbestos and fiberglass are in that dust.

RAY: The New York City Department of Public Health recommends that, at a minimum, you clean the car's interior and as much of the vents as you can with a HEPA-equipped vacuum. Then it recommends driving the car on the highway with the ventilation system off to allow the motion of the car to scatter some of the remaining dust.

TOM: That will certainly get rid of some of it -- but not all of it. The DPH also has a list of "optional" steps that it DOESN'T really recommend but that you CAN take if you're worried. Without going into detail, since there are too many to list, they basically involve removing, cleaning and sterilizing everything from the tassel hanging from your rear-view mirror, to the doggie on the back shelf with the head that goes up and down (we've posted the whole DPH list on our Web site, the Car Talk section of www.cars.com, for those who want to see it).

RAY: I'll tell you what I'd add to the basic DPH list: After driving with the ventilation system off, I would then open all of the windows and run the ventilation system with the fan on full blast for a while.

TOM: And the best thing to do, if you're really concerned about safety (or if you have asthma or breathing difficulties), is have all the ductwork of the ventilation system removed and wiped clean. It's expensive -- it's many hours of work -- but it's the only way to really get most of the dust out.

RAY: I'm not sure what I'd do if it were my car. After all, the same dust that's on your car was in the air for days or weeks, so you've already been breathing it. But on the other hand, the inside of a car is a closed environment, and you don't want to lengthen your exposure unnecessarily.

TOM: Well, I know what I'd do.

RAY: What's that?

TOM: After I drove the car around with the fan on and the windows open, I'd lend it to my brother-in-law for a trip to Maryland. That no-good bum has been sleeping on my couch for two months.