Quando sento nausea in viaggio, apro un po’ il finestrino e respiro lentamente.

Quando means when. In this sentence it introduces a situation that happens repeatedly or generally:

• Quando sento nausea in viaggio... = When I feel nauseous while traveling...

It is not just one specific moment in the future; it describes a habitual reaction. Italian often uses quando + present tense for this kind of general statement.

Because Italian uses the present tense not only for what is happening now, but also for habits, general truths, and repeated actions.

So:

• Quando sento nausea in viaggio, apro... e respiro...

means something like:

• Whenever I feel nauseous while traveling, I open the window a little and breathe slowly.

In English, we also often use the present for routines: When I feel sick, I open the window.

Both are possible, but they are slightly different in feel.

• avere nausea = to be nauseous / to have nausea
• sentire nausea = to feel nauseous / to feel nausea

In this sentence, sento nausea emphasizes the physical sensation as it comes on.
A very natural alternative would be:

• Quando ho nausea in viaggio...

That would also be correct and common.

In Italian, some nouns referring to physical sensations or conditions can appear without an article, especially in general expressions.

So:

• sento nausea = I feel nauseous / I feel nausea

This sounds natural and idiomatic.

You may also hear:

• sento la nausea
• ho la nausea

but in many cases nausea without the article sounds smoother and more general.

In viaggio means while traveling, when traveling, or on a journey/trip.

It is a very common Italian expression. It does not necessarily mean one long trip; it can refer generally to being in transit.

Examples:

• Leggo spesso in viaggio. = I often read while traveling.
• Mi stanco facilmente in viaggio. = I get tired easily when traveling.

In your sentence, in viaggio tells us the context in which the nausea happens.

Italian usually does not need the subject pronoun, because the verb ending already shows who the subject is.

• apro = I open
• respiro = I breathe
• sento = I feel

So io is normally omitted unless you want emphasis or contrast.

For example:

• Io apro il finestrino, ma lui no. = I open the window, but he doesn’t.

In the original sentence, io would sound unnecessary.

Un po’ means a little, a bit.

So:

• apro un po’ il finestrino = I open the window a little

It softens the action and suggests the window is not opened fully.

You could also think of it as modifying the verb:

• I open the window a little bit

Because po’ is the shortened form of poco.

• un poco = a little
• un po’ = a bit / a little

The apostrophe shows that the word has been shortened. This is the standard spelling.

So write:

• un po’

not:

• un pò ❌

Finestrino usually means a small window, and very often specifically a car window.

That makes it a very natural word in a travel sentence, especially if the speaker is in a car.

• finestra = window
• finestrino = little window / car window

So:

• apro il finestrino sounds like I open the car window

Italian often uses the definite article where English might use the, a, or even no article depending on context.

Here il finestrino refers to the window available in the situation, so the window is natural.

• apro il finestrino = I open the window

Using un finestrino would sound less natural here, as if you were introducing one window out of several in a more abstract way.

Yes, but the meaning or emphasis can shift slightly.

The original sentence:

• apro un po’ il finestrino

is very natural.

You may also hear:

• apro il finestrino un po’

This can sound like I open the window a little as well, but the rhythm is slightly different. The original placement is very common and smooth.

Both can work, but lentamente is more neutral and precise for slowly.

• lentamente = slowly
• piano = softly / gently / slowly, depending on context

With breathing, both are understandable:

• respiro lentamente
• respiro piano

But respiro lentamente is especially clear and standard if you want to emphasize the slow pace of breathing.

It is very normal and helpful.

In Italian, when a sentence begins with a clause like:

• Quando sento nausea in viaggio

a comma is commonly used before the main clause:

• Quando sento nausea in viaggio, apro un po’ il finestrino...

It makes the sentence easier to read. In short sentences, punctuation can sometimes vary, but the comma here is standard and natural.

Yes. Some natural alternatives are:

• Quando ho nausea in viaggio, apro un po’ il finestrino e respiro lentamente.
• Se mi viene nausea in viaggio, apro un po’ il finestrino e respiro lentamente.
• Quando mi sento nauseato in viaggio, apro un po’ il finestrino e respiro lentamente.

These all express similar ideas, but with slightly different wording:

• ho nausea = I am nauseous
• mi viene nausea = nausea comes on / I start to feel nauseous
• mi sento nauseato = I feel nauseous

The original sentence is perfectly natural.