Why are our a/c filters getting so black so soon?

Question

Lived at this new developement for 1 yr. this has been happening recently. Change a/c filters every month until lately it has been every two weeks.

Answer 1

Where do you live? If there are brush fires in the area, then the soot will clog up your a/c filters (and your lungs).

Road/home construction can kick up a lot of dust, too.

Answer 2

Could be soot.  See:

http://www.homeenergy.org/archive/hem.di...

Check the carbon monoxide (CO) levels in your home, like right now.  If elevated, then something is burning that is getting into your home.  Where there is CO, there is soot.