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Consolidated Human Activity Database (CHAD) for use in human exposure and health studies and predictive models

What is CHAD?

EPA scientists have compiled detailed data on human behavior from 22 separate exposure and time-use studies into EPA’s Consolidated Human Activity Database (CHAD). The database includes more than 54,000 individual study days of detailed human behavior, with each day broken down into individual hours and activity types. The data include demographic information, including age, sex, employment, and education level, which allows researchers to examine specific groups within the general population and how their unique behavior patterns influence their exposures to chemicals. The data in CHAD can help researchers understand the patterns of human behavior that influence their exposure to chemicals in their environment.

What are the benefits of using CHAD?

CHAD is regularly used as part of a wide variety of human exposure and health studies and has been cited in hundreds of articles on human exposure science. The data provided in CHAD is shown in a consistent format so researchers can create robust studies of human activity and exposure. CHAD data is freely available for download.

Who should use CHAD?

Data from CHAD are routinely used by EPA and other government agencies, academia, and private organizations for human exposure and health studies, and in models used for exposure and risk assessment.

How does CHAD work?

CHAD presents data from 22 exposure and time-use studies in a consistent, searchable format that scientists and researchers can download and use in human exposure studies, predictive models, and other research activities.

Where can I find more information?

Download Now:

Two versions of CHAD are available for download: CHAD-Master and CHAD-2000.

CHAD-Master is continuously maintained and updated as new human activity data become available. CHAD-Master contains human activity data from 22 different studies performed in 1982-2010. It is available for download in comma separated value (CSV) and SAS dataset formats.

CHAD-2000 is the original CHAD database in Microsoft Access Format. It contains detailed human activity data from 12 studies performed in 1982-1998 and provides a desktop user interface for exploring the data. CHAD-2000 has tables of additional original data collected in these 12 studies that are not available in CHAD-Master. As these data may be of interest to some researchers, EPA has made this legacy version available for download.

Technical Contacts:

Kristin Isaacs (