先把句子翻译出来：

The drawback is that wind is obviously unspecific as to where it takes the pollen.

【翻译】缺点是，风至于把花粉带到什么地方显然是无法确定的。

as to 是个“复合介词”，意思是“至于，关于；就……而言”。介词后面接 wh- 引导的名词性从句是常态。又如：

He is in no doubt as to what is needed.  

他很确定需要什么。

来自柯林斯例句

There's some question as to whether he will sign this resolution.  

他是否会签署这项决议还不能确定。

来自柯林斯例句

Jackie and Ben came to a joint decision as to where they would live.

关于他们将住哪里是杰姬和本共同决定的。

《柯林斯高阶英汉双解学习词典》

网友可以查一查 as to 的用法，很常见。