The Guardian, a highly reputable newspaper, seems to use "on/in" interchangeable after "impact".
Sentences 1 and 2 are mine, and I want to know if my reasoning for the usage of on/in after "impact" has any merit. I want to follow through on this "reasoning" consistently, and not write "on" one time and "in" another time. This is just for the use of "impact", not in general.
Ngram shows "impact on reducing" is more often used than "impact in reducing".
- The program's impact on reducing benefits . . .
Example: . . . family doctors can also have a dramatic impact on reducing emissions in the NHS . . . - The Guardian
- The program's impact in reducing benefits . . .
Example: . . . such a scheme could also have an impact in reducing the climate footprint of the global plastics . . . - The Guardian
The following is my understanding/reasoning:
We say impact on noun/noun phrase - the impact [of something] on the reduction of carbon emission.
We say impact in verb+ing - the impact [of something] in reducing carbon emission.
Note: I have looked at questions from ELU and ELL on the usage of "impact on/in". There is overwhelming preference for "impact on". But in those questions/answers, "impact on" is followed by a noun/noun phrase. None of them specifically talks about the use of "in" when what follows "impact in" is a verb+ing. That is what I am asking about. Here are a few that I have gone through: