This paper examines with a case study of Beijing, China, the health benefits that could be reaped from urban air quality improvements. The study implements a household survey to collect information about the yearly medical expenditures and lost days of work, to estimates the total costs of illness (COI) borne by a typical individual due to airborne diseases. The results of this survey provide a lower bound for the health costs borne by the urban population of Beijing due to air pollution. We find that the average individual COI in our sample is more than 3000 yuan per year, corresponding to almost one month of the average wage (slightly more than 500 US$ per year). This is quite sizeable, considering that it represents just the minimum benchmark for the damages caused by pollution to health. This result indicates that Beijing could benefit quite substantially from reducing air pollution in terms of health costs: if it could completely eliminate pollution, the savings in terms of COI would range in an order of magnitude of 21 million yuan per year only from hospitalized cases.