Noxious airs from trash discards, irrigation canals, marketplaces, hospitals, and plazas vitiated colonial Lima's environment. Using olfactory history, this article examines how residents reacted to their pungent environs. Early modern Iberians believed that foul smells were harmful. Fully understanding this relationship, municipal leaders subjugated the San Lázaro district by relocating its indigenous population and moving noxious trades and institutions to the area. I argue that the concentration of miasmas in San Lázaro represents an environmental conquest. San Lázaro's ethnically and socially diverse population lived with unhealthy airs that threatened their health. By contrast, central Lima enjoyed fresher airs in locations primarily occupied by Spanish vecinos (male, landowning citizens, who were allowed to participate in local politics) in and around the Plaza de Armas, the cathedral, the viceroy's palace, and the municipal hall. The protection of central Lima's airs reveals that environmental management corresponded to social status and political power.