Exposure assessments to air pollution typically focus on either personal or microenvironmental measurements. Personal measurements can provide more accurate individual exposures, but tend to be intrusive and expensive. Microenvironmental measurements are commonly cheaper and have more flexibility in size, number, and weight requirements of the instrumentation, but must be adjusted by time-activity information for the population of interest. Time-activity data has traditionally been difficult to obtain and imprecise using the available social-science methods or expensive with GPS and more sophisticated equipment. Deployment of new inexpensive, non-intrusive and time-activity measurement systems (TAMS), however, allows us to have the best of both worlds. In the Chronic Respiratory Effects of Early Childhood Exposure to Respirable Particulate Matter study being conducted in Guatemala the goal is to quantify personal exposures of young children and their mothers to CO and PM2.5 from cookstoves using wood fuel. A low-cost personal locator carried by the participants logs the time spent in the kitchen by receiving a digital ultrasound signature unique to each person (TAMS). 48-h exposure assessments based on both standard exposure assessment methods for 63 Guatemalan women and their children (35 using chimney woodstoves and 28 using open wood fires will be presented. Personal continuous and cumulative CO measurements, and kitchen measurements of continuous and cumulative CO and PM2.5 concentrations along with time-activity monitoring was conducted. By combining real-time CO and PM2.5 concentrations in the kitchen with the TAMS data, daily CO exposure attributable to kitchen smoke compared to other sources and the parts of the cooking process that cause the most exposure can be determined. This work provides further validation of the value of such simple inexpensive precise sensor-based technologies for exposure assessment in remote settings. [1] For more information about the study, please visit our web site at: http://ehs.sph.berkeley.edu/guat/page.asp?id=1 For more information about this seminar, please contact: Bill Fisk(510 )486-5910