Browsing by Author "Wu, Connor Y. H."

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    Effect Modification by Environmental Quality on the Association between Heatwaves and Mortality in Alabama, United States
    Jian, Yun; Wu, Connor Y. H.; Gohlke, Julia M. (MDPI, 2017-09-28)
    Background: Previous studies have shown that heatwaves are associated with increased mortality. However, it remains unclear whether the associations between heatwaves and mortality are modified by the environmental quality. Methods: We used the United States (US) Environmental Protection Agency’s Environmental Quality Index (EQI) and its five domain indices (air, water, land, built, and sociodemographic) to represent the cumulative environmental quality. We applied a time-stratified case-crossover design to analyze the disparities in the association between heatwaves and non-accidental deaths (NAD) among counties with different environmental qualities, in metropolitan areas in Alabama (AL), United States. Results: We found significant associations between heatwaves and NAD and a significant effect modification of this relationship by EQI. There were higher odds ratios in counties with the worst cumulative environmental qualities compared to counties with the best cumulative environmental qualities. For example, the percent change in odds ratio (mean and (95% CI)) between heatwave days and non-heatwave days was −10.3% (−26.6, 9.6) in counties with an overall EQI of 1 (the best overall environment) and 13.2% (4.9, 22.2) in counties with an overall EQI of 3 (the worst overall environment). Among the five domains, air quality had the strongest effect modification on the association. Conclusion: Our findings provide evidence that the associations between heatwaves and NAD vary among areas with different environmental qualities. These findings suggest that integration of air quality and heatwave warning systems may provide greater protection to public health.
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    Effect of an Additional 30 Minutes Spent Outdoors during Summer on Daily Steps and Individually Experienced Heat Index
    Wang, Suwei; Richardson, Molly B.; Wu, Connor Y. H.; Zaitchik, Benjamin F.; Gohlke, Julia M. (MDPI, 2020-10-17)
    Spending time outdoors is associated with increased physical activity; however, high ambient temperature/humidity, together with built environment features in urban versus rural environments, may influence physical activity. We conducted an intervention trial with 89 urban and 88 rural participants performing normal activities on Days 1–2 (baseline) and spending an additional 30 min outdoors on Days 3–7 (intervention) in the summer. Participants wore a pedometer with real-time visual feedback to track daily steps taken and a thermometer clipped to their shoe to track temperatures experienced individually. Hygrometer–thermometers were deployed in participants’ neighborhoods to collect finer resolution ambient heat indexes in addition to regional weather station measurements. Using linear mixed effects models and adjusting for ambient conditions and individual-level factors, participants on average walked 637 (95%CI (83, 1192)) more steps and had a 0.59 °C (95%CI (0.30, 0.88)) lower daily mean individually experienced heat index during intervention days compared to baseline days. The intervention benefit of increased physical activity was greater in rural residents who were less active at baseline, compared to urban residents. Our results suggest adding a small amount of additional time outdoors may improve physical activity without increasing participants’ heat exposure, even during summer in a humid subtropical climate.
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    Navigable rivers facilitated the spread and recurrence of plague in pre-industrial Europe
    Yue, Ricci P. H.; Lee, Harry F.; Wu, Connor Y. H. (Springer Nature, 2016-10-10)
    Infectious diseases have become a rising challenge to mankind in a globalizing world. Yet, little is known about the inland transmission of infectious diseases in history. In this study, we based on the spatiotemporal information of 5559 plague (Yersinia pestis) outbreaks in Europe and its neighboring regions in AD1347-1760 to statistically examine the connection between navigable rivers and plague outbreak. Our results showed that 95.5% of plague happened within 10 km proximity of navigable rivers. Besides, the count of plague outbreak was positively correlated with the width of river and negatively correlated with the distance between city and river. This association remained robust in different regression model specifications. An increase of 100 m in the width of river and a shortening of 1 km distance between city and river resulted in 9 and 0.96 more plague outbreaks in our study period, respectively. Such relationship shows a declining trend over our study period due to the expansion of city and technological advancement in overland transportation. This study elucidates the key role of navigable river in the dissemination of plague in historical Europe.
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    Trade routes and plague transmission in pre-industrial Europe
    Yue, Ricci P. H.; Lee, Harry F.; Wu, Connor Y. H. (Springer Nature, 2017-10-11)
    Numerous historical works have mentioned that trade routes were to blame for the spread of plague in European history, yet this relationship has never been tested by quantitative evidence. Here, we resolve the hypothetical role of trade routes through statistical analysis on the geo-referenced major trade routes in the early modern period and the 6,656 geo-referenced plague outbreak records in AD1347-1760. Ordinary Least Square (OLS) estimation results show that major trade routes played a dominant role in spreading plague in pre-industrial Europe. Furthermore, the negative correlation between plague outbreaks and their distance from major trade ports indicates the absence of a permanent plague focus in the inland areas of Europe. Major trade routes decided the major plague outbreak hotspots, while navigable rivers determined the geographic pattern of sporadic plague cases. A case study in Germany indicates that plague penetrated further into Europe through the local trade route network. Based on our findings, we propose the mechanism of plague transmission in historical Europe, which is imperative in demonstrating how pandemics were spread in recent human history.
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    Zooming in on adverse birth outcomes in coalfield regions of Central Appalachia
    Marston, Michael L.; Wu, Connor Y. H.; Smith, Ethan D.; Gohlke, Julia M.; Kolivras, Korine N.; Krometis, Leigh-Anne H. (Virginia Tech. Powell River Project, 2018)
    Health disparities account for significant differences in mortality and morbidity risks in Central Appalachia (encompassing parts of WV, KY, TN and VA) compared to other U.S. regions, yet research addressing environmental factors potentially contributing to these health disparities is lacking. Central Appalachia offers a unique opportunity to examine environmental exposures associated with resource extraction. Coal production from large surface mines was the dominant resource extraction method in the 1990s-2000s and is now decreasing as other resource extraction methods increase. We hypothesize that health risks associated with air and water pollution exposure are greater for Central Appalachian residents living within close proximity to active surface mines. The results described here begins to link exposure with health outcomes using individual-level birth record data. We have extended spatiotemporal characterization of boundaries associated with surface mining between 1990 and 2015 in all Central Appalachia counties. Results indicate that from 1990 to 2015, 1806 km2 of land across the study area was disturbed by mining activities, which equates to approximately 4.2% of the study-defined Central Appalachia region. Temporal trends show a decreasing amount of active surface mining sites over the study period. Using a previously developed surface mining dataset that only covered southwest Virginia coalfields, we tested the hypothesis that maternal address proximity to active surface mining was positively associated with preterm birth. No significant association was found; however the sample size (n=5008) was very small due to poor geocoding rates, particularly in earlier years, and overall low number of births between 1990-2015 in this small, rural area (n=14,269). Our next steps will be to improve inference and precision in effect estimates by increasing sample size with inclusion of data from TN, KY and WV, application of the accuracy–assessed surface mining extent dataset described here to improve estimate of proximity to active surface mining, and inclusion of watershed boundaries, drinking water violation datasets, as well as airshed characterization. Ultimately, we hope this research will aid in determining the underpinnings of health disparities in Central Appalachian communities, ultimately leading to research, policy and practice improvements that may be generalizable to other rural areas beyond Central Appalachia.