Excessive Grease in Above Stove Microwave
Cleaning the traps often is another way of dealing with this problem.  If you are going to cook with a lot of grease or oil this will happen.  

If you can remove the traps easily then soak them in Dawn dishwashing soap (and hot water) or 409 Cleaner.  I have used both and they work.  Let the traps soak in either one for awhile to eat away the built up grease, then rinse with hot water and let air dry.

Or just change cooking habits.  Less Oil/Grease and go to steaming.
Good luck.