1979 Santana Air Injection?

I have a mystery pump on my 1979 Santana 2.25 diesel, which I’m assuming is an air pump as the hoses connect to the air intake plug. It runs off a second, very small belt driven off the crank and is mounted under the alternator.

I can’t find any specifics for this pump. I did find the section on air injection in the green book but it’s not clear to me exactly what it’s for.

What are the benefits? Any drawbacks besides taking up space?

I have an air injection pump on my 2.6L its supposed to reduce smoke by injecting air into the exhaust and also help reduce burnt valves. It was part of the early emissions controls.
I have no idea if it does much or not, mine is slightly different from yours but suspect it does the same thing