Which is a direct benefit of prohibiting nicotine and tobacco use in schools?

The prevention of second hand smoke, is a direct benefit of prohibiting nicotine and tobacco use in schools. The prevention of second hand smoke, is a direct benefit of prohibiting nicotine and tobacco use in schools. 

well when looking at this if you think about it   negativley and positivley   react with each other and when the first layer gets full they add layers it starts with 2 on the first layer and it constantly goes on until the official number is there