Measuring potential exposure to environmental pollutants: time spent with soil and time spent outdoors.

In 1994-1995, the Electric Power Resource Institute (EPRI) undertook a major national survey of time in microenvironments with 1200 respondents aged 18 and older. It did so using a methodology that minimized the problems of respondent recall and reporting by the use of a "time diary," in which survey respondents reported in detail about their actual activities "yesterday" including time spent outdoors. In addition, respondents were asked questions about the extent of contact with soil they had on that day. Significant proportions (20%) of the American public reported coming in direct contact with soil on a typical day and those who did come in contact were exposed for about 1.7 h per day; some 6% of the public reported being exposed for more than 2 h on the day in question, mainly by hand (although 3% of respondents reported soil contact with their head or face). As expected, men reported far more soil contact than women; surprisingly few consistent differences were found by age, or by marital status, parental status or employment status. Contrary to expectations, higher contact was not reported by minorities, or by less educated or less affluent respondents. Moreover, these patterns generally remained unchanged after adjustment for other demographic predictors. More as expected, higher exposure was reported in the Spring months, on weekends, and in rural areas and in the South and West regions of the country, patterns again largely unaffected by multivariate controls for other predictors. In general, while certain predictors of soil exposure were much the same for time spent outdoors, there were some notable exceptions.