Insalubrious: not conducive to health. Note that what is good is characterized as healthy and what is bad is characterized as unhealthy, which is especially significant given that Austen wrote Sanditon while suffering from poor health herself.

https://www.merriam-webster.com/dictionary/insalubrious

Links to common words/themes throughout the annotations

This is the first reference to the title of the novel in "Sanditon". Note that Sanditon is an entirely fictional town created by Austen, which I find impressive given that she has only previously dabbled in creating villages. Sanditon is notably described as a bathing-place, and thus she might draw some inspiration from the time she spent in Bath.

Source: http://janeausten.wikia.com/wiki/Sanditon_(town)

In this chapter, we are introduced to the Parkers who are from Sanditon and are traveling. There seems to be heavy focus on health, probably due to the fact Austen was sick at this point in her life.