Avoiding toxic solvents.
To make oil painting safe, it's important to avoid toxic solvents such as: turpentine, varsol, mineral spirits, white spirits, petroleum distillates, paint thinners and odourless paint thinners.
These all release toxic volatile compounds into the air, which is then unsafe to breathe.
So, here is a little video to show how oil painting brushes can be cleaned safely, by simply using plain walnut or linseed oil. Use artist's quality oil for best results. The oil is re-usable if the paint is allowed to settle to the bottom of a small container with a lid. When it's too dirty to use anymore, remove the accumulated paint with a paper towel. Allow the paper towel to thoroughly and completely dry out before throwing it in the trash.
Wash the brushes with plain soap and water at the end of the day. If brushes are allowed to dry with oil in them, they will become hard and unusable.