Integrating data from multiple time-location measurement methods for use in exposure assessment: the Multi-Ethnic Study of Atherosclerosis and Air Pollution (MESA Air)

Tools to assess time-location patterns related to environmental exposures have expanded from reliance on time-location diaries (tlds) and questionnaires to use of geospatial location devices such as data-logging global positioning system (gps) equipment. the multi-ethnic study of atherosclerosis and air pollution obtained typical time-location patterns via questionnaire for 6424 adults in six us cities. at a later time (mean 4.6 years after questionnaire), a subset (n=128) participated in high-resolution data collection for specific 2-week periods resulting in concurrent gps and detailed tld data, which were aggregated to estimate time spent in various microenvironments. during these 2-week periods, participants were observed to spend the most time at home indoors (mean of 78%) and a small proportion of time in-vehicle (mean of 4%). similar overall patterns were reported by these participants on the prior questionnaire (mean home indoors: 75%; mean in-vehicle: 4%). however, individual micro-environmental time estimates measured over specific 2-week periods were not highly correlated with an individual’s questionnaire report of typical behavior (spearman’s ρ of 0.43 for home indoors and 0.39 for in-vehicle). although questionnaire data about typical time-location patterns can inform interpretation of long-term epidemiological analyses and risk assessment, they may not reliably represent an individual’s short-term experience.