Our 3/4" Extreme Rubber Tiles can be installed outdoor year-round with no issues. These tiles are resistant to the elements and are very slip-resistant and even more so when wet. They are also very easy to clean and maintain and are mold and mildew resistant. In regards to being used as flooring for a play area, they definitely can, but they are not fall height rated. So if you need a floor with that rating, we recommend checking out our wide range of playground flooring. You can install these tiles over dirt, as long as it is compacted and flat. You will also want to make sure that any large debris is removed from the area where these tiles will be installed.