With a bit of Googling, I realize how easy it is to replace the in-cabin air filter. So I went out and got this Purolator C35491 BreatheEASY Cabin Air Filter
Here is what I did: First, open up the glove compartment and unscrew the hinge on the right side
After that, the glove box should come off easily. The air filter cover should now be exposed and easily accessible. Press on the clip at both end of the air filter cover
Remove the cover. Now you can pull out and and replace the in-cabin air filter. Put everything back together and you are good to go!
Just thought I would give you a bit of motivation to take some action: This is the old air filter I pulled out of my car. Yes, OMFG!
After I replace the filter, I notice I don't sneeze in my car anymore. And I am not sure if it is related, but I no longer smell that weird order after I turn on the A/C.
So people, please check your air filter to see if it needs to be replaced. It is very cheap and very easy to do!