В салоне машины было душно, поэтому я открыл окно.

It was stuffy inside the car, so I opened the window.

Breakdown of В салоне машины было душно, поэтому я открыл окно.

• я: I
• в: in
• быть: to be
• машина: the car

Questions & Answers about В салоне машины было душно, поэтому я открыл окно.

Why is it было душно and not something like был душный or была душная?

Because душно is not an adjective here. It is a word of state, used in impersonal sentences to describe an environment or condition: it was stuffy, it was cold, it was dark, etc.

Russian often uses this pattern:

• было душно = it was stuffy
• было холодно = it was cold
• было темно = it was dark

Since there is no real grammatical subject, the verb in the past tense takes the default neuter singular form было.

So В салоне машины было душно literally works like:

• In the car interior, it was stuffy

Why is there no subject in the first part of the sentence?

Because this is an impersonal sentence, which is very common in Russian.

English often uses a dummy subject like it:

• It was stuffy in the car

Russian usually does not need an equivalent dummy subject. It simply says:

• В салоне машины было душно

So the sentence is complete even without a word meaning it.

What case is в салоне машины, and why?