The line "sweet airs" makes me think of another phrase commonly used by Shakspeare: "sweet breath." I like the use of the word "sweet" to denote pleasant smells. In those days having sweet breath was no mean feat: and often perfumed substances and herbs were used to mask bad body odors or rotting teeth. People of means did not bathe regularly but would spend a fortune on powders, colognes and rare spices to create an aura of pleasant fragarance around them...

To stave off plague, people in Shakspeare's day carried pomanders (literally "pomme ambre" or apple made of ambergris), some literally made with apples stuck with cloves, etc and rolled in mixtures of rose petals, musk, civet, rosemary, myrrh and other resins...the volatile essential oils of these materials actually do contain antiseptic properties, hence their usefulness in combating infection. Perfumers and apothecaries who worked with such ingredients daily were all but immune to the plague...but most people believed it was the sweet smell of perfumes which cleared the noxiousness from the disease-ridden air...

peg