Abstract  Using distributions of time spent at various ventilation levels, ranges of inhalation exposure in the population can be established. Distributions of exposure time were determined using results of a study by the California Air Resources Board (CARB) which focused on time spent by humans participating in various activities and the locations where the activities occurred. The daily at-home activities from the CARB study were assigned to one of three ventilation levels, generating aggregate time periods. Distinct age and gender populations were identified, and distributions for aggregate time were established for these populations at each of the ventilation levels. In addition to aggregate time spent at home, distributions for various ages and genders were established for aggregate time spent at school and work. By combining distributions of aggregate time with corresponding ventilation rates, the distribution of inhalation rates can be established for at home, at work, and at school exposures.

Abstract  Contaminated site cleanup decisions may require estimation of dermal exposures to soil. Telephone surveys represent one means of obtaining relevant activity pattern data. The initial Soil Contact Survey (SCS-I), which primarily gathered information on the activities of adults, was conducted in 1996. Data describing adult behaviors have been previously reported. Results from a second Soil Contact Survey (SCS-II), performed in 1998-1999 and focused on children's activity patterns, are reported here. Telephone surveys were used to query a randomly selected sample of U.S. households. A randomly chosen child, under the age of 18 years, was targeted in each responding household having children. Play activities as well as bathing patterns were investigated to quantify total exposure time, defined as activity time plus delay until washing. Of 680 total survey respondents, 500 (73.5%) reported that their child played outdoors on bare dirt or mixed grass and dirt surfaces. Among these "players," the median reported play frequency was 7 days/week in warm weather and 3 days/week in cold weather. Median play duration was 3 h/day in warm weather and 1 h/day in cold weather. Hand washes were reported to occur a median of 4 times per day in both warm and cold weather months. Bath or shower median frequency was seven times per week in both warm and cold weather. Finally, based on clothing choice data gathered in SCS-I, a median of about 37% of total skin surface is estimated to be exposed during young children's warm weather outdoor play.

Abstract  The 1975-1981 TIME USE LONGITUDINAL PANEL STUDY dataset combines a round of data collected in 1981 with the principal investigators' earlier TIME USE IN ECONOMIC AND SOCIAL ACCOUNTS, 1975-1976 (ICPSR 7580), collected by F. Thomas Juster, Paul Courant, et al. This combined data collection consists of data from 620 respondents, their spouses if they were married at the time of first contact, and up to three children between the ages of three and seventeen living in the household. The key features which characterized the 1975 time use study were repeated in 1981. In both of the data collection years, adult individuals provided four time diaries as well as extensive information related to their time use in the four waves of data collection. Information pertaining to the household was collected, as well as identical measures from respondents and spouses for all person-specific information. Selected children provided two time diary reports (one for a school day and one non-school day), an academic achievement measure, and survey measures pertaining to school and family life. In addition, teacher ratings were obtained. For each adult individual who remained in the sample through the 1981 study, a time budget was constructed from his or her time diaries containing the number of minutes per week spent in each of some 223 mutually exclusive and exhaustive activities. These measures provide a description of how the sample individuals were currently allocating their time and are comparable to the 87 activity measures created from their 1975 diaries. In addition, respondent and spouse time aggregates were converted to parent time aggregates for mothers and fathers of children in the sample. To facilitate analyses on spouses, a merged data file was created for 868 couples in which both husband and wife had complete Wave I data in either 1975-1976 or 1981.

Abstract  We review the factors influencing children's exposure to environmental contaminants and the data available to characterize and assess that exposure. Children's activity pattern data requirements are demonstrated in the context of the algorithms used to estimate exposure by inhalation, dermal contact, and ingestion. Currently, data on children's exposures and activities are insufficient to adequately assess multimedia exposures to environmental contaminants. As a result, regulators use a series of default assumptions and exposure factors when conducting exposure assessments. Data to reduce uncertainty in the assumptions and exposure estimates are needed to ensure chemicals are regulated appropriately to protect children's health. To improve the database, advancement in the following general areas of research is required: identification of appropriate age/developmental benchmarks for categorizing children in exposure assessment; development and improvement of methods for monitoring children's exposures and activities; collection of activity pattern data for children (especially young children) required to assess exposure by all routes; collection of data on concentrations of environmental contaminants, biomarkers, and transfer coefficients that can be used as inputs to aggregate exposure models.

Abstract  Reports that 10 million workers changed occupations between January 1986 and January 1987--and about 90 million stayed put. Provides Current Population Survey information on how long workers stay in an occupation or with an employer. (JOW)

Abstract  In the report, the authors review data on the methodological background and results from the 1987-88 California Air Resources Board (CARB) time activity study and from a similar 1985 national study of Americans' Use of Time conducted at the University of Maryland, College Park. In order to facilitate comparisons, data from the study were recorded to be as compared as possible to the CARB code categories. In general, the data on average distributions of time in activities matched up rather well across the two samples. Despite some differences, the two data sets overall showed remarkably similar patterns of activity. That was less true for the locations codes, however. Several sources of discrepancy were found in the comparison of these data. A recording of location data from the national study provided some resolution of the differences that were found, but several differences remained. The strong similarities of the average time for the activity data indicate that the California data could be used to generate a better set of location codings for the national data. A major reason for analyzing time-diary data is to estimate time spent in various microenvironments. Microenvironments refer neither solely to activities nor solely to locations but to the combination of activities and locations that yield potential exposures of which 16 were defined for comparison. The analysis confirms Californians spent more time in transit and in outdoor environments.

Abstract  BACKGROUND Health risk assessment requires both information about the dose-response relationship for a toxic agent and details on the exposure. Such details include information on ambient concentrations and on the presence and activites of individuals. These factors can vary over time, space, and type of environment. Activity data are particularly important because vigorous exercise can increase the breathing rate, affecting respiratory organ exposure and altering response to air pollution. Despite the strong need for activity pattern data, surprisingly little such information exists for the general population. OBJECTIVES To determine and characterize the activity patterns of a randomly chosen population. APPROACH The project team developed data collection instruments (including diaries) and aprotocol to select arandom sample of about 1000 peope including children and the elderly, in greater Cincinnati, Ohio. About haK the group participated in a three day study during March 1987, and the other half in a similar study in August 1987, recording all of their activities in the diaries. After collecting and validating the diaries through interviews, the team coded and analyzed data for 941 subjects to provide general tabulations about the study population. They then constructed graphs for populations and subpopulations. showing the probability that an individual would be exercising sufficiently to induce fast breathing for at least 10 minutes, by hour of day, indoor and outdoor environment, day of week, and study-month. They also determined the distribution of the length of time individuals exercised in various times and environments. RESULTS Analysis of study data helped establish the probability that a randomly chosen person in the study population during specified time periods would be exercising heavily outdoors and thus risking increased response to environmental pollutants. For a given hour on a weekday in March this probability is less than 0.03. In August and on weekends, the maximum probability that an individual is exercising heavily outdoors can reach 0.07. Diaries showed that people under 19 years old performed the greatest portion of exercise. EPRI PERSPECTIVE When announcing they would defer any decision on a short-term S02 standard, EPA noted that the type of data collected here can complement those from controlled human studies. Specifically, in a discussion on short-term S02 concentrations of health concern, EPA stated that "normal day-to-day activity patterns further reduce the chance that such concentrations will result in exposure conditions approximating those that produced effects in controlled human studies" (Federal Register, 53(80), April 26, 1988, p. 14934). This use of activity data clearly demonstrates how important such data can be in estimating the probability that pollutants may affect human health. The data collected from this sample group—which matches attributes of U.S. populations with similar climates and subpopulations—are an important part of health risk assessment

Abstract  This report describes the purposes, methods, and preliminary findings of the first large-scale survey of children's activity patterns done in the United States. The survey was commissioned by the California Air Resources Board (ARB) in 1988 and was conducted by the staff of the Survey Research Center, University of California, Berkeley, during the period April 1989 through February 1990. A sample of 1,200 California children aged 11 and under (and adult informants living in the child's household) was selected by random digit-dialing methods and interviewed by phone to determine potential exposure to selected sources of air pollution and to ascertain (via a time diary) the children's activities and locations during a 24-hour period. Time spent in various locations and activities and proportions potentially exposed to air pollutants are reported by child's age (0-2 years, 3-5 years, 6-8 years, and 9-11 years), child's gender, season· of interview, and region of residence (Southern Coast, San Francisco Bay Area, and "Rest of State") . Comparisons between the ARB Children's Activity Survey and the earlier ARB Adult Activity Survey are alsoprovided.

Abstract  This review describes current patterns and long-term trends (up to 50 years when possible) related to (a) physical activity, (b) employment and occupation, (c) travel behavior, (d) land use, and (e) related behaviors (e.g., television watching). On the basis of available data, the following trends were observed according to type of physical activity: relatively stable or slightly increasing levels of leisure-time physical activity, declining work-related activity, declining transportation activity, declining activity in the home, and increasing sedentary activity. These result in an overall trend of declining total physical activity. Large differences were noted in the rates of walking for transportation across metropolitan statistical areas. A strong linear increase existed in vehicle miles traveled per person over the past half century, coupled with a strong and consistent trend toward Americans living in suburbs. Although it is difficult to precisely quantify owing to the lack of long-term data, it is apparent that a combination of changes to the built environment and increases in the proportion of the population engaging in sedentary activities put the majority of the American population at high risk of physical inactivity.

Abstract  Although the impact of environmental contaminants on human health has been widely studied, few reports in the Canadian literature have focussed on the specific vulnerability of children. Because of their rapid growth, physiologic and metabolic immaturity, the fetus and child are often at increased risk from toxic substances in their environments. Furthermore, greater air, food and fluid intakes relative to body weight compared with the adult, increase the child's potential for excessive exposures. The crawling stage of infancy, the play patterns and short stature of toddlers also serve to increase their exposure to dust and heavy and volatile substances which accumulate near the floor. This article provides an overview of some of the developmental physiologic, anatomic and behavioural features of the fetus, infant and child which increase their vulnerability to environmental contaminants in comparison with adults. Specific examples are given.

Abstract  This study examined the links between childhood obesity, activity participation and television and video game use in a nationally representative sample of children (N = 2831) ages 1-12 using age-normed body mass index (BMI) ratings. Results indicated that while television use was not related to children's weight status, video game use was. Children with higher weight status played moderate amounts of electronic games, while children with lower weight status played either very little or a lot of electronic games. Interaction analyses revealed that this curvilinear relationship applied to children under age 8 and that girls, but not boys, with higher weight status played more video games. Children ages 9-12 with lower weight status used the computer (non-game) for moderate amounts of time, while those with higher weight status used the computer either very little or a lot. This was also true for the relationship between print use and weight status for children of all ages. Results also indicated that children with higher weight status spent more time in sedentary activities than those with lower weight status.

Abstract  Global positioning system (GPS) technology is used widely for business and leisure activities and offers promise for human time-location studies to evaluate potential exposure to environmental contaminants. In this article we describe the development of a novel GPS instrument suitable for tracking the movements of young children. Eleven children in the Seattle area (2-8 years old) wore custom-designed data-logging GPS units integrated into clothing. Location data were transferred into geographic information systems software for map overlay, visualization, and tabular analysis. Data were grouped into five location categories (in vehicle, inside house, inside school, inside business, and outside) to determine time spent and percentage reception in each location. Additional experiments focused on spatial resolution, reception efficiency in typical environments, and sources of signal interference. Significant signal interference occurred only inside concrete/steel-frame buildings and inside a power substation. The GPS instruments provided adequate spatial resolution (typically about 2-3 m outdoors and 4-5 m indoors) to locate subjects within distinct microenvironments and distinguish a variety of human activities. Reception experiments showed that location could be tracked outside, proximal to buildings, and inside some buildings. Specific location information could identify movement in a single room inside a home, on a playground, or along a fence line. The instrument, worn in a vest or in bib overalls, was accepted by children and parents. Durability of the wiring was improved early in the study to correct breakage problems. The use of GPS technology offers a new level of accuracy for direct quantification of time-location activity patterns in exposure assessment studies.

Abstract  EPA's National Exposure Research Laboratory (NERL) has combined data from 12 U.S. studies related to human activities into one comprehensive data system that can be accessed via the Internet. The data system is called the Consolidated Human Activity Database (CHAD) and is available at http:// www.epa.gov/nerl/. CHAD contains 22,968 person days of activity and is designed to assist exposure assessors and modelers in constructing population "cohorts" of people with specified characteristics that are suitable for subsequent analysis or modeling. This paper describes the studies comprising CHAD and the various intellectual foundations that underlay the gathering of human activity pattern data. Next, it provides a brief overview of the Internet version of CHAD, and discusses how the program was formulated. Emphasis is placed on how activity-specific energy expenditure estimates were developed. Finally, the paper recommends steps that should be taken to improve the collection of activity data that would improve energy expenditure estimates and related information needed for physiologically based exposure dose modeling efforts.

Abstract  Protocols used to assess human exposure to chemicals in soils at contaminated sites often include a dermal pathway. Use of default parameters to assess dermal exposure to soil can easily lead to risk projections that appear to warrant remedial action. However, because those default parameters are typically highly uncertain, risk estimates based upon them inspire little confidence. To better characterize assumptions regarding dermal exposures, a telephone survey instrument was developed to elicit information on behaviors relevant to assessment of dermal contact with soil and dust. Participation in four activities--gardening, other yard work, outdoor team sports, and home construction or repair involving digging--was investigated. Questions were also asked regarding clothing choices and post-activity bathing practices. The survey was administered to two populations of approximately 450 adult respondents each using random digit dialing. The first was a national (U.S.) sample. The second sample was drawn from counties surrounding the Hanford Nuclear Reservation. Seventy-nine percent of the regional respondents and 89% of the national respondents reported participating in at least one of the four targeted activities. Responses of doers regarding clothing choices suggest that median fractions of skin exposed during warm-weather activities typically exceed the 25% often assumed. The Hanford sample differed from the national sample in the fraction residing in single-family homes, the fraction describing their residential surroundings as rural, and in ethnic makeup. The Hanford population displayed greater rates of participation than the national sample in three activities that have an obvious link to residence in a single-family dwelling: home repair involving digging, gardening, and other yard work, but differences were not explained entirely by residence type. The regional population also reported greater frequency of participation in multiple activities. In contrast, clothing choices among doers could not be distinguished between the two groups.

Abstract  Generally, men have been in their current occupations longer than have women, whites longer than blacks, and college graduates longer than those with less education; almost half of the 55- to 59- year-olds have been in their current occupations at least 20 years.