Earlier in a policy change, Google had imposed restrictions to mobile publishers that involves the placing of 300x250 sized ad units on mobile webpages, addressing the digital advertising ecosystem on mobile for everyone - users, advertisers and publishers.
Now, starting May 2, Google has removed this limitation, and effective immediately, now allow this sized unit on mobile webpages to be placed above the fold.
For taking off this limitations, Google says, after a careful review, they've believe that when the 300x250 sized ads are implemented above the fold in a user-friendly way, "the ads don't distract users, or result in ad performance issues.
Google further reminds publishers, even though this ad unit is now allowed above the fold, you must still ensure the ads on mobile site layouts do not push the page content below the fold. Because, not only does this create annoyance, distraction, or ad performance issues, but it could also lead to accidental clicks by the users when the scroll the page.
"To ensure a good user experience, we still recommend the site content should be clear and accessible above the fold," google said.
In the picture below, you can see an example of unacceptable use of the larger sized ads:
See our optimization guide for the mobile Web for tips on where to place your ads.
"it's important to provide a good user experience for your mobile audience. By focussing on your mobile site's design, content, and ad placements you could help to increase user engagement. In turn, this could lead to an increase in your mobile ad revenue in the long-term," writes google.