Dandan Xu

The effect of high temperature on cause-specific mortality: A multi-county analysis in China

Although existing studies have linked high temperature to mortality in a small number of regions, less evidence is available on the variation in the associations between high temperature exposure and cause-specific mortality of multiple regions in China. Our study focused on the use of time series analysis to quantify the association between high temperature and different cause-specific mortalities for susceptible populations for 43 counties in China. Two-stage analyses adopting a distributed lag non-linear model (DLNM) and a meta-analysis allowed us to obtain county-specific estimates and national-scale pooled estimates of the nonlinear temperature-mortality relationship. We also considered different populations stratified by age and sex, causes of death, absolute and relative temperature patterns, and potential confounding from air pollutants. All of the observed cause-specific mortalities are significantly associated with higher temperature. The estimated effects of high temperature on mortality varied by spatial distribution and temperature patterns. Compared with the 90th percentile temperature, the overall relative risk (RR) at the 99th percentile temperature for non-accidental mortality is 1.105 (95%CI: 1.089, 1.122), for circulatory disease is 1.107 (95%CI: 1.081, 1.133), for respiratory disease is 1.095 (95%CI: 1.050, 1.142), for coronary heart disease is 1.073 (95%CI: 1.047, 1.099), for acute myocardial infarction is 1.072 (95%CI: 1.042, 1.104), and for stroke is 1.095 (95%CI: 1.052, 1.138). Based on our findings, we believe that heat-related health effect in China is a significant issue that requires more attention and allocation of existing resources.

Short-term exposures to PM 2.5 and cause-specific mortality of cardiovascular health in China

Background: Many multi‐center epidemiological studies have robustly examined the acute health effects of exposure to low concentrations of fine particulate matter (PM2.5) on cardiovascular mortality in developed counties. However, data limitations have resulted in few related studies being conducted in developing counties with high levels of PM2.5 exposure. In recent years, people in China with a heavy cardiovascular disease burden have been exposed to particularly high levels of PM2.5. Objective: We conducted a multi‐county time series study investigating the acute effects of PM2.5 on the increased risk of cardiovascular death across China, and explored subpopulations susceptible to PM2.5 exposure. Methods: Appling a county‐specific Poisson regression in 30 Chinese counties, we estimated PM2.5 effects on all‐cause mortality and cause‐specific mortality of cardiovascular health for 2013–2015. We also considered PM2.5 effects on several subpopulations, including males, females, and three age groups (< 65, 65–74 and > 74 years old). We pooled the county‐specific results across China using a random effects meta‐analysis by cause and by subpopulation. Results: We found a 0.13% (95% confidence interval (CI), 0.04–0.22) increase in all‐cause mortality, a 0.12% increase (95% CI, 0.001–0.25) increase in cardiovascular disease (CVD), a 0.42% (95% CI, 0.03–0.81) increase in AMI, a 0.17% (95% CI, −0.04–0.40) increase in coronary heart disease, and a 0.13% (95% CI, −0.12–0.33) increase in stroke in association with a 10‐&mgr;g/m3 increase in PM2.5 concentrations on the same day. The magnitudes of the associations were less than those reported in developed counties with lower PM2.5 levels. A vulnerable effect on all‐cause mortality was observed in the elderly population (older than 65 years) and on CVD in males. Conclusions: This study showed the positive magnitude of PM2.5 effects with high exposure on all natural, CVD, and cause‐specific mortality and on the susceptible populations in China. The findings complemented evidence related to exposure‐mortality relationships at the higher end of short‐term exposure to PM2.5 on a global scale. HIGHLIGHTSExploring the association between PM2.5 and cardiovascular mortality in China.Suggesting that people 65–74 years old and males might be more vulnerable to PM2.5.Showing the difference of PM2.5 acute effect between developed countries and China.

Design and application of a web-based real-time personal PM 2.5 exposure monitoring system

Growing demand from public health research for conduct large-scale epidemiological studies to explore health effect of PM2.5 was well-documented. To address this need, we design a web-based real-time personal PM2.5 exposure monitoring system (RPPM2.5 system) which can help researcher to get big data of personal PM2.5 exposure with low-cost, low labor requirement, and low operating technical requirements. RPPM2.5 system can provide relative accurate real-time personal exposure data for individuals, researches, and decision maker. And this system has been used in a survey of PM2.5 personal exposure level conducted in 5 cities of China and has provided mass of valuable data for epidemiological research.

The association of ambient PM 2.5 with school absence and symptoms in schoolchildren: a panel study

BackgroundChildren are a susceptible population to exposure of ambient fine particulate air pollution (PM2.5), and the associated symptoms are sensitive prevalent indicators of morbidity. However, few studies to date investigate the association between PM2.5 exposure and school absence and symptoms.MethodsIn a panel study including 20,291 observations in 615 schoolchildren 8–13 years of age, we asked the participants to record their school absence and symptoms on every school day from 17 November to 31 December 2014 in Jinan, China. We used the generalized linear mixed effects models to examine the adverse effects of ambient PM2.5 on school absence and symptoms, adjusting for covariates including meteorological and individual factors.ResultsThe 3-day moving average of PM2.5 was significantly associated with school absence (1.37; 95% CI: 1.07–1.74) and increases in symptoms of the throat (1.03; 95% CI: 1.00–1.05), nose (1.03; 95% CI: 1.01–1.06), and skin (1.09; 95% CI: 1.06–1.12). High PM2.5 exposure also increased the risks of individual symptoms, especially for cough (1.02; 95% CI: 1.00–1.04), sneezing (1.03; 95% CI: 1.00–1.07), and stuffy nose (1.09; 95% CI: 1.02–1.17).ConclusionHigh PM2.5 exposure is a risk factor for the health of schoolchildren. Allocation of medical resources for children should take into account the ambient PM2.5 concentrations and be proportioned accordingly.

Acute effect of multiple ozone metrics on mortality by season in 34 Chinese counties in 2013-2015

Although numerous multicentre studies have estimated the association between ozone exposure and mortality, there are currently no nationally representative multicentre studies of the ozone–mortality relationship in China.

Effects of ambient temperature on myocardial infarction: A systematic review and meta-analysis

Previous studies have suggested that ambient temperature is associated with the mortality and morbidity of myocardial infarction (MI) although consistency among these investigations is lacking. We performed a meta-analysis to investigate the relationship between ambient temperature and MI. The PubMed, Web of Science, and China National Knowledge Infrastructure databases were searched back to August 31, 2017. The pooled estimates for different temperature exposures were calculated using a random-effects model. The Cochrans Q test and coefficient of inconsistency (I2) were used to evaluate heterogeneity, and the Eggers test was used to assess publication bias. The exposure-response relationship of temperature-MI mortality or hospitalization was modeled using random-effects meta-regression. A total of 30 papers were included in the review, and 23 studies were included in the meta-analysis. The pooled estimates for the relationship between temperature and the relative risk of MI hospitalization was 1.016 (95% confidence interval [CI]: 1.004-1.028) for a 1 °C increase and 1.014 (95% CI: 1.004-1.024) for a 1 °C decrease. The pooled estimate of MI mortality was 1.639 (95% CI: 1.087-2.470) for a heat wave. The heterogeneity was significant for heat exposure, cold exposure, and heat wave exposure. The Eggers test revealed potential publication bias for cold exposure and heat exposure, whereas there was no publication bias for heat wave exposure. An increase in latitude was associated with a decreased risk of MI hospitalization due to cold exposure. The association of heat exposure and heat wave were immediate, and the association of cold exposure were delayed. Consequently, cold exposure, heat exposure, and exposure to heat waves were associated with an increased risk of MI. Further research studies are required to understand the relationship between temperature and MI in different climate areas and extreme weather conditions.