The phrase "a very small impact" is correct and usable in written English.
It can be used to describe a minimal effect or influence that something has on a situation or outcome.
Example: "The new policy had a very small impact on employee productivity, as most workers were already accustomed to the previous guidelines."
Alternatives: "a minimal effect" or "a negligible influence".
Blocking them will have at best a very small impact on emissions.
The passenger mutations themselves have no or only a very small impact on the cell׳s fitness.
The enclosure had a very small impact on the tree canopy conductance (Gc).
However, Mr. Skilling said today that the Fastow partnerships had a very small impact on Enron's profits last year.
More recently John Hattie's seminal Visible Learning study concluded that homework overall had an effect size of 0.29 – in other words, a very small impact.
The figures reflect sales of single-family homes only, so Manhattan, a market that is dominated by apartments, has a very small impact.
If you raise the price of those inputs like corn and soybean oil, you have a very, very small impact on the prices consumers see when they make their food choices.
"So if you raise the price of those inputs like corn and soybean oil, you have a very, very small impact on the prices consumers see when they make their food choices".
They find that immigration, and especially recent immigrants, have a positive but very small impact on well-being of natives.
In fact the E°′ of the R173K mutant does not show any pronounced temperature dependence (please note in Table 3 the big errors, which are a consequence of the very small impact of temperature on E°′).
A study solely based on female participants didn't detect any effect of distance from powerlines on the report of NSPS [ 41] while a recent epidemiological study determining actual distance from BS using geo-coding, demonstrated a statistically significant but very small impact of actual distance on NSPS [ 5].
