Cabin Filter
When you bring your automobile to the dealership, service advisors always encourage you to change the engine air filter, but don't forget to ask about cabin air filter too. You care about your car's engine and you let it breathe in fresh, filtered, clean air. So do you, you have to let your lungs breathe in fresh clean air too.
The grey colored filter on right is my 5 months old cabin filter which I just took out, the white on left is a brand new filter, see the difference?
If you live in a contruction area, or if you drive a lot, and if you have a cabin filter in your car, don't forget to replace it constantly.
This is my own DIY cabin filter using 3M Filtrete MERV 11 rated filter purchased at Lowe's. It basically filters out dust, pollen, smoke, dandruff, grass, tiny leaves, bugs, etc without blocking off your normal AC air flow. Dealerships do carry specific filter for your car, but MERV is little lower than my expectation.
So next time when you turn on the AC and it's like rotten eggs smelled up the car, it's time to get the cabin filter changed. Breathe clean, breathe happy!