If you do not sell a mobile product you probably want to disable in app advertising.

I have found it brings nearly 0 conversions for regular websites.

To do this paste "adsenseformobileapps.com" in the “Placements” section of “Campaign Exclusions” from the Display Network tab.

More info on how to disable in app adwords advertising is here https://support.google.com/adwords/answer/1722057?hl=en