I'm the original owner of a 1996 pontiac bonneville SSEi. I used to have a short commute, but after moving to a Los Angeles surburb, it can be quite long. The evidence is quite strong and uncontroversial that living near a freeway (which I don't) causes, statistically speaking, major health problems. It'* therefore not a big leap to guess that breathing the exhaust from the car in front of you when you're stuck in traffic is bad for you as well. The exposure is shorter, but the concentrations must be higher. The fancy European cars like BMW and Audi offer interior activated carbon filters. Is there an aftermarket retrofit for an effective (non gimicky) activated carbon filter for the bonneville? Or am I SOL? I like my car otherwise. I just wish it had this feature.

the 2000+ bonnes have a cabin filter......i dont believe that there is anyway to fit one in to the 92-99 gen

I use a cigarette lighter based ionic breeze car filter (from Sharper Image). Works great.

What 1993SLE said. The intake for outside air is near the center of the windshield underneath the cowl and the passenger side drive post for the windshield wipers. You can get to it, but not without a ton of effort. It is covered on top and sealed on the bottom so that water will not enter the cars interior. The design would make a retrofit very difficult.

You could potentially cut some carbon filter material and insert it into each vent. I've thought of trying to find a way to do this myself, just to simply filter out the dust and pollen.