Our regional measures have had a significant impact on unemployment.
It will make the sentence more clear and understandable.
The impact of the meteor created a crater in the earth.The community has been badly impacted by sustained poverty.
She cast an oblique glance towards the door, suspecting that someone was eavesdropping on their conversation.
A compound subject for impact would have to be two words that are subjects in the beginning of the sentence and the word impact would have to be in the sentence somewhere.
Brace for impact - we'regoing in!Please hand me that impact wrench.
The baseball collided with his face with such an impact, that it broke his nose.
Greenhouse gases have had a significant impact on the environment.
The meteoroid collided with a devastating impact.
No, it is not grammatically correct. "Such a" can only be followed by a base-form adjective, like "large." If you want to make a comparative sentence, you might say, "Why do meteors have a MUCH larger impact on the Earth THAN on the moon."
Impact crater is now more prevalently used for the term impact basin.
The impact of the closing that factory will be huge on the local economy.
The impact of the crash caused the air bag to deploy.