Person: Shi, Liuhua
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Shi
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Liuhua
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Shi, Liuhua
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Publication Chronic effects of temperature on mortality in the Southeastern USA using satellite-based exposure metrics(Nature Publishing Group, 2016) Shi, Liuhua; Liu, Pengfei; Wang, Yan; Zanobetti, Antonella; Kosheleva, Anna; Koutrakis, Petros; Schwartz, JoelClimate change may affect human health, particularly for elderly individuals who are vulnerable to temperature changes. While many studies have investigated the acute effects of heat, only a few have dealt with the chronic ones. We have examined the effects of seasonal temperatures on survival of the elderly in the Southeastern USA, where a large fraction of subpopulation resides. We found that both seasonal mean temperature and its standard deviation (SD) affected long-term survival among the 13 million Medicare beneficiaries (aged 65+) in this region during 2000–2013. A 1 °C increase in summer mean temperature corresponded to an increase of 2.5% in death rate. Whereas, 1 °C increase in winter mean temperature was associated with a decrease of 1.5%. Increases in seasonal temperature SD also influence mortality. We decomposed seasonal mean temperature and its temperature SD into long-term geographic contrasts between ZIP codes and annual anomalies within ZIP code. Effect modifications by different subgroups were also examined to find out whether certain individuals are more vulnerable. Our findings will be critical to future efforts assessing health risks related to the future climate change.Publication Estimating Health Effects of Temperature and pm2.5 Using Satellite-Retrieved High-Resolution Exposures(2016-10-03) Shi, Liuhua; Schwartz, Joel; Koutrakis, Petros; Coull, BrentHuman activities emit greenhouse gases (GHGs) and air pollutants, which would affect the environment and in turn affect human health. Accurate estimate of the health effects requires high resolution exposure data of environmental stressors, such as air temperature (Ta) and fine particulate matter (PM2.5). The availability of those exposure data, however, is usually limited by sparsely distributed ground-based monitoring network. Therefore, the first chapter estimates Ta at a fine scale on a daily basis by incorporating satellite-based remote sensing data. Satellite can provide a global daily estimate of 1 km × 1 km surface temperature (Ts), which is correlated with Ta. Hence, a statistical calibration approach between Ta and Ts was used to retrieve daily mean Ta at1 km resolution for the Southeastern United States for the years 2000 to 2014. The second chapter investigates the chronic effects of temperature and temperature variability on mortality in New England, by using the satellite-retrieved daily mean Ta estimated from previous studies similar to our first chapter. Our findings indicate that the variability of atmospheric temperature emerges as a key factor of the potential health impacts of climate change. The last chapter examines the association between low-concentration PM2.5 and mortality in New England, by using the satellite-retrieved PM2.5 estimates. Our findings suggest that adverse health effects occur at low levels of fine particles, even for levels not exceeding the newly revised EPA standards.Publication Low-Concentration PM2.5 and Mortality: Estimating Acute and Chronic Effects in a Population-Based Study(National Institute of Environmental Health Sciences, 2015) Shi, Liuhua; Zanobetti, Antonella; Kloog, Itai; Coull, Brent; Koutrakis, Petros; Melly, Steven J.; Schwartz, JoelBackground: Both short- and long-term exposures to fine particulate matter (≤ 2.5 μm; PM2.5) are associated with mortality. However, whether the associations exist at levels below the new U.S. Environmental Protection Agency (EPA) standards (12 μg/m3 of annual average PM2.5, 35 μg/m3 daily) is unclear. In addition, it is not clear whether results from previous time series studies (fit in larger cities) and cohort studies (fit in convenience samples) are generalizable. Objectives: We estimated the effects of low-concentration PM2.5 on mortality. Methods: High resolution (1 km × 1 km) daily PM2.5 predictions, derived from satellite aerosol optical depth retrievals, were used. Poisson regressions were applied to a Medicare population (≥ 65 years of age) in New England to simultaneously estimate the acute and chronic effects of exposure to PM2.5, with mutual adjustment for short- and long-term exposure, as well as for area-based confounders. Models were also restricted to annual concentrations < 10 μg/m3 or daily concentrations < 30 μg/m3. Results: PM2.5 was associated with increased mortality. In the study cohort, 2.14% (95% CI: 1.38, 2.89%) and 7.52% (95% CI: 1.95, 13.40%) increases were estimated for each 10-μg/m3 increase in short- (2 day) and long-term (1 year) exposure, respectively. The associations held for analyses restricted to low-concentration PM2.5 exposure, and the corresponding estimates were 2.14% (95% CI: 1.34, 2.95%) and 9.28% (95% CI: 0.76, 18.52%). Penalized spline models of long-term exposure indicated a larger effect for mortality in association with exposures ≥ 6 μg/m3 versus those < 6 μg/m3. In contrast, the association between short-term exposure and mortality appeared to be linear across the entire exposure distribution. Conclusions: Using a mutually adjusted model, we estimated significant acute and chronic effects of PM2.5 exposure below the current U.S. EPA standards. These findings suggest that improving air quality with even lower PM2.5 than currently allowed by U.S. EPA standards may benefit public health. Citation Shi L, Zanobetti A, Kloog I, Coull BA, Koutrakis P, Melly SJ, Schwartz JD. 2016. Low-concentration PM2.5 and mortality: estimating acute and chronic effects in a population-based study. Environ Health Perspect 124:46–52; http://dx.doi.org/10.1289/ehp.1409111Publication Impacts of Temperature and its Variability on Mortality in New England(2015) Shi, Liuhua; Kloog, Itai; Zanobetti, Antonella; Liu, Pengfei; Schwartz, JoelRapid buildup of greenhouse gases is expected to increase the Earth surface mean temperature, with unclear effects on temperature variability1–3. This adds urgency to better understand the direct effects of the changing climate on human health. However, the effects of prolonged exposures to temperatures, which are important for understanding the public health burden, are unclear. Here we demonstrate that long-term survival was significantly associated with both seasonal mean values and standard deviations (SDs) of temperature among the Medicare population (aged 65+) in New England, and break that down into long-term contrasts between ZIP codes and annual anomalies. A rise in summer mean temperature of 1 °C was associated with 1.0% higher death rate whereas an increase in winter mean temperature corresponded to 0.6% lower mortality. Increases in temperature SDs for both summer and winter were harmful. The increased mortality in warmer summers was entirely due to anomalies, while it was long term average differences in summer SD across ZIP codes that drove the increased risk. For future climate scenarios, seasonal mean temperatures may in part account for the public health burden, but excess public health risk of climate change may also stem from changes of within season temperature variability.