This is the 15396th most frequent Polish word.
spalin
"Spalin" is the genitive plural form of "spaliny," meaning "exhaust fumes" or "emissions" in English.
The word 'spalin' is the genitive plural form of 'spaliny', which means exhaust gases, used here to indicate what is being emitted by the car.
Samochód emituje dużo spalin.
The car emits a lot of exhaust gases.
Here, 'spalin' again is in the genitive plural form, specifying what the filter captures.
Filtr w moim samochodzie zatrzymuje większość spalin.
The filter in my car captures most of the exhaust gases.
In this sentence, 'spalin' is used in the genitive plural case to describe the type of smell being referred to.