During and immediately after the American Revolution, US writers described a salubrious national climate that would ensure the prosperity of the nation. Maintaining a good climate involved managing air quality through various forms of so-called improvement. In the 1790s, a series of yellow fever epidemics upended this fantasy and suggested that the US atmosphere might be either fundamentally toxic or incredibly vulnerable to foreign contagion. During this period, maintaining healthy air came to be understood as a national security issue. This discourse offers one point of origin for the contemporary militarization of climate to the benefit of some and at the expense of others. The heightened vulnerability of poor and nonwhite communities to airborne toxins can also be traced to the 1790s, when the government prioritized the health of white bodies at the expense of black people. This chapter traces this arc through Mercy Otis Warren’s anti-British plays, writing by and about Benjamin Franklin, and the novels of Charles Brockden Brown. The chapter closes by connecting this literary history to contemporary scholarship about air pollution.