Firstly My Salutations to all the readers. . Children can't be harmful. They can be either harmed or endangered. So you should use it like this Children are more harmed..... Or Children are more endangered.... Whichever suits your need best. But Here It will like this If, we don't care for our planet, children will be the most harmed( one who suffer the most). Because we produce excessive pollution, which is damaging the air we breathe. Thank You With Regards Shiekh Mohammad Anam