There is one thing I would like to point out about Buick cabin air filters in general, specifically my 2000 Regal LSE. Have you ever noticed the *musty* smell in older Buicks? When its warm and humid, and your car has been sitting for a while you may notice this most. This is because your Cabin air filter area lets in water and can fill up if its absolutely down pouring. At a minimum in these conditions your cabin air filter will be wet and will draw in moisture through your airvents inevitably fogging up your windshield if youdont blast it with A/C. A a maximum that water pools up so much that it actually starts pouring through your passenger side vents closest to cabin air filter.
My car is normally in a garage, I found this cabin air filter issue out because I left it outside in an overnight downpour. I left a pair of shoes on my front passenger seat floor area under the far right middle passenger vent, they were absolutely soaked from the watr leaking in the vent. This can somewhat be fixed by installing your own water shield (I used tin foil) so water does not liteally waterfall onto the filter. Humidity does not help with allegies/congestion!
Here is a youtube link showing you what i'm talking about