CHAD is a database that includes many useful activity pattern data sets, and can be downloaded from the USEPA website. It includes the National Human Activity Pattern Survey (NHAPS) data.

From the website: " [The] Consolidated Human Activity Database (CHAD) contains data obtained from pre-existing human activity studies that were collected at city, state, and national levels. CHAD is intended to be an input file for exposure/intake dose modeling and/or statistical analysis. CHAD is a master database providing access to other human activity databases using a consistent format. This facilitates access and retrieval of activity/and questionnaire information from those databases that EPA currently has access to and uses in its various regulatory analyses ...."

Since children may be at higher risk of adverse health than adults from exposure to toxic pollutants in air, food, and soil -- due to their smaller, developing bodies, and their potential for prolonged contact with soil and dust -- a child-specific exposure factors handbook has been created by the U.S. Environmental Protection Agency.

From the website: "The document provides a summary of the available and up-to-date statistical data on various factors assessing children exposures. These factors include drinking water consumption, soil ingestion, inhalation rates, dermal factors including skin area and soil adherence factors, consumption of fruits and vegetables, fish, meats, dairy products, homegrown foods, breast milk, activity patterns, body weight, consumer products and life expectancy."

The U.S. Environmental Protection Agency's Exposure Factors Handbook is a useful compilation of data relevant to the assessment of human exposure to environmental pollutants. It provides quantitative inputs for exposure models, including human activity patterns, building characteristics, and physical characteristics of humans.

The U.S. Center for Disease Control (CDC) provides valuable exposure information on Americans for a wide variety of environmental chemicals.

From the website: "The National Report on Human Exposure to Environmental Chemicals provides an ongoing assessment of the U.S. population's exposure to environmental chemicals using biomonitoring. Biomonitoring is the assessment of human exposure to chemicals by measuring the chemicals or their metabolites in human specimens such as blood or urine."

This website is run by the U. S. National Institutes of Standards and Technology (NIST) (Building and Fire Research Laboratory; Indoor Air Quality and Ventilation Group), and it is the home of the CONTAM multizone model, which runs on the Windows and GNU/Linux platforms and can be downloaded for free.

The website aims to "...foster the development and facilitate the application of multizone ventilation and indoor environmental modeling in the areas of building design, operation, maintenance, investigation and research." "....[Y]ou will find software tools for performing multizone analysis, information on the applications of multizone modeling, multizone modeling case studies, and references to multizone modeling publications."

USEPA-NERL is a United States government laboratory dedicated to research on human exposure. The lab funds exposure studies and conferences, develops exposure software, and informs health-related policy. The EPA publishes the Exposure Factors Handbook, which contains much data relevant to the modeling of human exposure.