不太对.首先,Nowadays就表示是现在,后面不能用过去时.另外,whether后面加or not有点多余了,you之后时态不明.可以用should.最后prop up it 改为prop it up.
建议改为：
Nowadays ,an increasing number of people concern about（or as to）the phenomena.However ,whether you should prop it up has caused heated debate.