Bad Air Days: The Effect of Air Stagnation during Pregnancy on Birth Outcomes and Infant Mortality in the U.S. and Mexico

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Project Summary/Abstract Despite the documented relationship between climate and extreme weather events, to date, there remain important gaps in scientific knowledge regarding how and the extent to which human health may be damaged by climate-related weather events, both directly and indirectly, domestically and internationally. We propose to identify air stagnation as a unique and critical environmental determinant of health and to assess its effects on newborns. Air stagnation, characterized by low wind and absence of precipitation, can lead to air pollution episodes and is expected to intensify and lengthen as a changing climate shifts global wind and precipitation patterns. However, little is known about its implications for human health. We focus on birth outcomes of newborns and infant mortality because evidence of the relationship between in-utero exposures to environmental hazards and fetal health and infant mortality remains insufficient to infer causality, the modes of exposure, sizes of the effects, and critical timings of the exposures. The analysis takes advantage of the unique and exogenous variation in daily air stagnation events and the comprehensive natality and mortality datasets with geocoded residential locations from Michigan, Pennsylvania, and Mexico collected for nearly a decade. These features allow us to precisely estimate the intensity of exposures to air stagnation experienced by individual mothers over the terms of their pregnancies by trimester. Our preliminary evidence, based on the monthly occurrence of air stagnation events in Michigan, indicates statistically and economically significant associations between air stagnation events during gestation and birth outcomes. Given these findings, we hypothesize that air stagnation is a critical environmental determinant of health, and we will assess its effects on newborns. We also hypothesize that there are important heterogeneities in the effects of air stagnation across different climate regions and demographic characteristics. These hypotheses will be addressed by the following Specific Aims: (1) Construct air stagnation events data at the daily level, which substantially refines the estimation of pollution exposure measures and expands the coverage to include Pennsylvania and Mexico; (2) Determine the effects of in-utero exposure to air stagnation on birth outcomes of newborns’ health and infant mortality; and (3) Determine the heterogeneity in the effects of air stagnation between the U.S. and Mexico, and within the countries by socioeconomic status. The anticipated outcomes will help policy makers design successful mitigation and adaptation policies, such as development of an alert warning system and identify and protect sensitive populations. In addition, it will advance knowledge regarding health effects of climate change-related extreme weather events by providing rigorous scientific evidence using real-time health, weather, geospatial, and exposure data.