Exhalar vs. espirar
The Spanish language is rich in verbs that describe the nuances of human actions, including the act of releasing air from the lungs. Two such verbs are 'exhalar' and 'espirar', each of which has its own context and connotations in use, although they share the basic meaning of breathing out.
Exhalar
'Exhalar' is a verb that means to breathe out or to expel air, vapour or a scent from the lungs or from something else. It can be used both literally and figuratively.
Exhaló profundamente para calmarse.
(He breathed out deeply to calm himself.)
La tetera comenzó a exhalar vapor.
(The teapot began to emit steam.)
Exhaló un suspiro de alivio.
(She let out a sigh of relief.)
Espirar
'Espirar' generally means to breathe out, in the specific context of living organisms expelling air from the lungs. It is usually used in a formal or medical context.
El doctor me pidió que espirara lentamente durante la auscultación.
(The doctor asked me to breathe out slowly during auscultation.)
Tras correr, es importante inhalar y espirar correctamente para recuperarse.
(After running, it's important to inhale and exhale correctly for recovery.)
Summary
While 'exhalar' and 'espirar' both refer to the act of breathing out or exhaling, 'exhalar' has broader applications, including the exhalation of substances other than air and figurative expressions of relief or emotion. On the other hand, 'espirar' is more specifically linked to the physical act of expelling air from the lungs, often in formal or medical discourse.