Asthma rates are steadily increasing in many cities throughout the United States. This trend, combined with the U.S. Environmental Protection Agency’s stricter air quality standards, results in thousands of children and sensitive populations being affected by poor air quality every day. To help sensitive individuals plan for and avoid poor air quality, the Sacramento Metropolitan Air Quality Management District developed a real-time notification system called AirAlert. AirAlert notifies people via e-mail, text pager, or digital cell phone so they can take appropriate actions to reduce exposure to elevated levels of ozone air pollution. The AirAlert system ingests hourly real-time data and notifies subscribers when the air quality rises above certain health levels of the Air Quality Index (AQI). Surveys from AirAlert users reveal the usefulness and benefits of this system on public health. This paper describes the AirAlert system in greater detail and presents analysis of how subscribers use AirAlert.