It's not a matter of whether it's generally desirable for all children to spend three hours outside every day. One problem is whether admonishing parents about

It's not a matter of whether it's generally desirable for all children to spend three hours outside every day. One problem is whether admonishing parents about it is actually going to make it so for all children. Another problem is whether it's actually possible and safe for all children no matter how desirable it might be in general. A third problem is how the strong the sun actually is while they are outside playing. For five days out of seven in the winter millions of children in northern Europe travel to school around sunrise, get maybe an hour outside during the day, then come home and play football under grey evening skies and sodium lights.