This article explores the relationship between qi and air in Chinese medical and scientific history in order to illuminate current approaches to air pollution and wumai (smog) in contemporary China. The modern concept of air is expressed in Chinese using terms related to the word qi. However, qi is a complex, multivalent term with a long history in Chinese cosmology and Chinese medicine and does not hold a clear one-to-one correspondence with air. Qi provided a resonating transcendent link between humans and their environment, yet pathogenic forms of qi arising from the environment could invade the body, causing illness and death. During the late nineteenth century, laboratory definitions of air as gas were introduced to China through the term qi, enabling some turn-of-the-century Chinese physicians such as Tang Zonghai to establish creative correspondences between air and qi that encompassed gas, vital energies, and even God. Such correspondences with their transcendent, potentially sacred valences appear to be unavailable today, even as contemporary Chinese embrace traditional medicines to ward off the effects of wumai. By probing the significant spaces between air and qi, this article suggests that the history of science in China has implications for how we might cope with and confront our current atmospheric crisis.