Sentence:  When he turned into the highway that led to the outskirts of the city and then rose toward home , he had to pull over to the curb and wait for a few minutes , sucking in <WSD>air</WSD> and squinting and blinking his eyes to clear them of tears . 
Meaning of the word marked with <WSD> tags:  a mixture of gases (especially oxygen) required for breathing; the stuff that the wind consists of