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Exposure Research

EMI Frequently Asked Questions

What is EMI?
EMI is a model that predicts individual exposures for multiple air pollutants from ambient concentrations, meteorology, and questionnaire information such as building characteristics, occupant behavior related to building operation, indoor sources, and time-activity patterns.

Who is developing EMI?
EMI is being developed, evaluated, and applied by EPA scientists working in conjunction with collaborators at University of Michigan, Harvard University, Applied Research Associates, the German Research Center for Environmental Health, and the National Children's Study.

Who will use EMI?
Intended users of EMI include health scientists in government, academia, and industry who perform epidemiologic analysis for air pollution cohort health studies. Development and evaluation of EMI is being driven by the needs of the health studies. For this interdisciplinary research effort, several close collaborations have been established with health scientists performing cohort health studies both within and outside EPA, including collaborators in the National Health and Environmental Effects Research Laboratory, University of Michigan, the National Children’s Study, and the German Research Center for Environmental Health.

What does EMI provide its users?
Initially, EMI will provide exposure metrics for specific air pollutants associated with four cohort health studies that examine: (1) cardiovascular events for diabetics in central North Carolina, (2) development of asthma for children across the country (National Children’s Study), (3) exacerbation of asthma for children living near major roadways in Detroit, Michigan, and (4) respiratory effects for asthmatics in central North Carolina.

Will users of EMI need specialized software?
No. EMI is being developed using software that will create standalone executables for royalty-free distribution to EMI users.

What is unique about EMI?
EMI requires sufficient questionnaire information from individuals to provide inputs for the model. EMI uses this individual-level input data to predict individual exposures for specific people in health studies. The goal of EMI is to estimate exposures for specific people rather than population variability, therefore EMI incorporates individual time-location activity diaries from health study participants to assemble longitudinal time-location-activity profiles that are specific to each individual being assessed.

How does EMI relate to other research within EPA?
Some EMI modules being developed and evaluated could be applied in other EPA exposure models. For example, the air exchange rate model could be integrated into population-level exposure models such as EPA’s SHEDS model. Also, EMI can be coupled with other models such as air quality models and lung dosimetry models to improve understanding of the source to effects continuum.

How does EMI relate to the National Children's Study?
EPA is coordinating with the National Children’s Study (NCS) Program Office to apply EMI for air pollutants related to the NCS asthma hypotheses, to help design NCS questionnaires to support EMI application and reduce participant burden, and to use EMI to help plan NCS pilot studies.

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