A totally normal human solution:
The answer here is circular breathing, a common technique employed by wind instrument players, allowing them to hold notes for a very long time.
Here is a very nice example of the technique being perpetrated by a saxophonist. Yes, ladies and gentlemen -- forty seven minutes five and one half seconds of the same note without pausing for a breath. I am certain he could have continued for much longer, but the sound engineers were already threatening murder by about twenty-five minutes in.
Super Duper Girl can very easily blow The Prankster, Emu, Mrs. Slushy, the Irate Haberdasher, and all the rest of the dastardly gang of vile villains and eerie evildoers infesting MetroCity away using this same technique!
The reason why Super Duper Girl uses this technique, as opposed to Hairy Tongue Halitosis's compressed air trick is that she can easily outlast the villain's stinky breath, thus saving thousands of MetroCity's beleaguered citizens from pulling their own noses off their faces in an attempt to stop smelling his pungent mal aire!
Super Duper Villain Compressed Air Technique
Hairy's technique involves starting the process of inhalation normally, by expanding his ribs and diaphragm, to get the air flowing into his lungs. Now, Hairy is a pretty stout fellow, and under normal respiratory conditions, his lungs can hold about 7 or 8 litres of air. But once he breaks out into his trademark neck-thrust/chest-compression stance (looks better in the comix than I can describe here, I assure you!), a kind of rapid peristaltic movement is engaged by super human muscles in his trachea & bronchus. The combination of rapid peristalsis drives litre after litre of air into his body, while the hyper flexion of his chest and core muscles causes all that air to be compressed. He can easily compress about five gallons of air --- 20 litres without breaking a sweat; and with a little more effort, he can compress ten gallons of air --- 40 litres. Of course, the downside is that Hairy has an (untried) maximum volume / maximum compression strength. He could possibly force the air to become liquid, but he will eventually run out of space to store even liquid air!
I can assure you, no normal citizen of MetroCity can withstand anything like twenty litres of Grade A Stinky Air! It's gotten to the point, where all Hairy Tongue Halitosis has to do is show up in a deli or shop and people literally start giving things to him, just hoping he'll go away before he starts breathing on everything!
Super Duper Hero Circular Breathing Technique
On the other hand, Super Duper Girl, takes an entirely different approach. In order to accomplish her super duper skill, she must first puff out her cheecks and purse her lips. She can easily put Dizzy Gillespie to shame:
She then uses Circular Breathing to periodically inhale air through the nose and into her lungs, and periodically exhale air through her mouth; while at the same time, inflating her cheeks & controlling the back of her oral cavity, thus closing it off, so she can continually exhale an uninterrupted flow of air through her mouth, even while breathing in.
There is no downside to Super Duper Girl's power: she can do circular breathing long after Hairy Tongue Halitosis has gasped the last of his super villain breath, and she'll still be blowing strong!