Environmental heat in relation to child health outcomes

Abstract

In the United States, annual average temperature is projected to rise throughout the 21st century, and both extremely hot days and heat waves are expected to become more intense and frequent. Global climate change is already negatively affecting human health and with continued warming, adverse health outcomes are expected to be exacerbated, especially among already susceptible populations, like children. This dissertation responds to the call for scientific research on potential health consequences of climate change among children. Pregnant women and children, especially infants, are considered vulnerable to a number of climate-sensitive health outcomes, including heat stress, respiratory disease, and diarrheal illness. Specifically, with the three studies described here, we aimed to contribute to the growing body of research establishing baseline relationships between environmental heat and child health outcomes in the United States. For Studies 1 and 2, we examined exposure to heat wave, defined multiple ways, in relation to preterm birth and pediatric asthma, respectively, using meteorological data from University of Massachusetts, Lowell and health data from the Massachusetts Department of Public Health. The first study overall found little to no short-term association between maternal heat wave exposure and preterm birth among women in ten large Massachusetts cities, using five definitions of heat wave. However, there were potential differences by gestational age that should be explored further in future studies. Findings from the second study provided some evidence for increased rates of emergency department (ED) visits for asthma/wheeze, among Massachusetts children during and immediately following heat waves, although excess numbers were small. Rates of all-cause pediatric ED visits were also elevated during heat waves and the days following, corresponding to hundreds of excess visits. For Study 3, we used national data from the U.S. Centers for Disease Control and Prevention’s Laboratory-based Enteric Disease Surveillance system to evaluate the association between temperature-based season and incident Salmonella infection in infants. Results confirmed elevated rates of infant infection in the summer compared to winter and revealed a greater absolute impact among infants compared to other age groups, especially in the South and for Salmonella serotypes commonly from environmental, non-food sources. Findings from this dissertation should not be viewed in isolation, but rather as part of a growing body of scientific literature on the potential impacts of climate change on child health. This work provides evidence that environmental heat is associated with certain adverse health outcomes among children in the U.S. and raises questions for further research. Results could be used as a baseline and compared with future estimates to assess changes in vulnerability and inform public health interventions