Environmental causes of chronic diseases are hard to identify. Measuring amounts of hazardous substances in our environment in a standard way—tracing the spread of these over time and area, seeing how they show up in human tissues, and understanding how they may cause illness—is critical. The National Environmental Public Health Tracking Network, developed by the Centers for Disease Control and Prevention (CDC), is a tool that can help connect these efforts.

Collected data is presented in maps, tables, and charts, and is downloadable for further exploration. Data types include:

• Health effect data: Data about health conditions and diseases, such as asthma and birth defects.
• Environmental hazard data: Data about chemicals or other substances, such as carbon monoxide and air pollution in the environment.
• Exposure data: Data about the amount of a chemical in a person's body, such as lead in blood.
• Other data: Data that helps us learn about relationships between exposures and health effects. For example, information about age, sex, race, and behavior or lifestyle choices that may help us understand why a person has a particular health problem.

The Tracking Network is part of CDC's National Environmental Public Health Tracking Program. The Tracking Program includes not only the Tracking Network, but the people, resources, and program management involved in building this network. The CDC provides funds to 26 state and local health departments to develop local tracking networks, which feed into the National Tracking Network.