What would be the human physiological reaction to an alien biosphere?

This is the first question about colonizing an alien world; the second question on agriculture on this planet is here.

So here's the idea: human beings travel to and land on an Earth-like world with the intention of colonizing it.

This world is remarkably Earth-like: gravity close to 1G, oxygen-nitrogen atmosphere with very close to the same proportions as Earth, similar climate, and similar life forms. So, in principle, a human could walk around unprotected on this world.

However...

The life on this planet, while at a similar level of development to that of Earth, is not based on the same DNA/RNA bases or the same amino acids in proteins. In short, the lifeforms on this planet resemble Earth life, but the chemistry is different.

What would happen if a human stepped out on the surface of this planet?

My thought is that they would experience a serious (probably life-threatening) allergic reaction as they breathe in dust, bacteria, etc. with completely different proteins that they have never encountered before. But is that correct? After all, here on Earth people have allergic reactions to proteins which are made up of our familiar set of amino acids; would they have similar reactions to proteins made up of unfamiliar amino acids?

posted over 5 years ago

Kryten‭

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