The National Human Activity Pattern Survey (NHAPS): a resource for assessing exposure to environmental pollutants

Abstract

Because human activities impact the timing, location, and degree of pollutant exposure, they play a key role in explaining exposure variation. This fact has motivated the collection of activity pattern data for their specific use in exposure assessments. The largest of these recent efforts is the National Human Activity Pattern Survey ( NHAPS ), a 2 -year probability -based telephone survey ( n = 9386 ) of exposure -related human activities in the United States ( U.S. ) sponsored by the U.S. Environmental Protection Agency ( EPA ). The primary purpose of NHAPS was to provide comprehensive and current exposure information over broad geographical and temporal scales, particularly for use in probabilistic population exposure models. NHAPS was conducted on a virtually daily basis from late September 1992 through September 1994 by the University of Maryland's Survey Research Center using a computer -assisted telephone interview instrument ( CATI ) to collect 24 -h retrospective diaries and answers to a number of personal and exposure -related questions from each respondent. The resulting diary records contain beginning and ending times for each distinct combination of location and activity occurring on the diary day ( i.e., each microenvironment ). Between 340 and 1713 respondents of all ages were interviewed in each of the 10 EPA regions across the 48 contiguous states. Interviews were completed in 63% of the households contacted. NHAPS respondents reported spending an average of 87% of their time in enclosed buildings and about 6% of their time in enclosed vehicles. These proportions are fairly constant across the various regions of the U.S. and Canada and for the California population between the late 1980s, when the California Air Resources Board ( CARB ) sponsored a state -wide activity pattern study, and the mid -1990s, when NHAPS was conducted. However, the number of people exposed to environmental tobacco smoke ( ETS ) in California seems to have decreased over the same time period, where exposure is determined by the reported time spent with a smoker. In both California and the entire nation, the most time spent exposed to ETS was reported to take place in residential locations.

It's about time: A comparison of Canadian and American time–activity patterns

“…Detailed survey methodology of the two surveys has been previously published (Klepeis et al, 2001;Leech et al, 1996;Nelson et al, 1996;Tsang and Klepeis 1996 ).…”

“…While several approaches to recording time -activity data have been used, ranging from self -administered recall to directly supervised observation, the 24 -h recall diary has found general acceptance after its application by the California Air Resources Board for exposure assessment (Wiley et al, 1991 ). Using a similar 24-h recall diary the United States' Environmental Protection Agency undertook a random sample telephone survey of the time and activity patterns throughout the continental USA in 1992 to 1994, the National Human Activity Pattern Survey ( NHAPS ) (Klepeis et al, 2001 ). This study compares the NHAPS results to a survey using the same methodology in a smaller random sample within four Canadian cities in 1996-1997, the Canadian Human Activity Pattern Survey ( CHAPS ) (Leech et al, 1996 ).…”

Comparison of global positioning system (GPS) tracking and parent-report diaries to characterize children's time–location patterns

“…When dealing with transient peaks of environmental contaminants, knowing whether or not a person is in a particular microenvironment is the first step toward determining if exposure may occur (Klepeis et al, 2001;McCurdy and Graham, 2003). Time-location has been measured using self-report diary instruments for many years (Robinson, 1988;Wallace et al, 1987Wallace et al, , 1991Freeman et al, 1993Freeman et al, , 1999.…”

Exposure time and place: Do COPD patients differ from the general population?

“…Subjects reported spending 75% of waking hours indoors and 11% in vehicles; these would approximate to 87% and 7%, respectively of a 24-h period. This time indoors for example would be similar to, but the time in vehicles would be greater than, NHAPS data (Klepeis et al, 2001).…”

“…Random sample populations in California (Wiley et al, 1991), the continental USA (National Human Activity Pattern Survey or NHAPS) (Klepeis et al, 2001), and Canada (Canadian Human Activity Pattern Survey or CHAPS) (Leech et al, 1996) have used this method; comparisons have shown very little difference in time and activity patterns over 24 h in normal subjects in these populations (Leech et al, 2001;Johnson et al, 1993).…”