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Background Evidence of association of ambient air pollution with cause-specific emergency department visits in China is still limited. This study aimed to investigate short-term associations between exposures to air pollutants and daily cause-specific emergency department visits using a large-scale multicenter database involving a total of 65 sentinel hospitals in Guangzhou, the most densely-populated city in south China, during 2013–2015. Material and methods We obtained data on 162,771 emergency department visits from 65 hospitals from the Emergency Medical Command Center in Guangzhou between January 1, 2013 and December 31, 2015. Daily air pollution data on particulate matter (PM) of aerodynamic diameter 10 , and PM 2.5 , respectively), sulfur dioxide (SO 2 ), nitrogen dioxide (NO 2 ) and ozone (O 3 ) were collected from the Daily Quality Report of the Guangzhou Environmental Protection Bureau during the study period. Visits for neurologic, respiratory and circulatory diseases were assessed in relation to air pollutants using Poisson generalized additive models. Results Mean daily number of emergency department visits for neurologic, respiratory and circulatory diseases was 89, 24 and 35, respectively. After adjustment for other pollutants (PM 2.5 , PM 10 , NO 2 and O 3 ), meteorological factors and time-varying confounders, a 7.98-μg/m 3 (interquartile range) increment in 2-day moving average of same-day and previous-day SO 2 concentrations was associated with the statistically significant increase of 4.89% (95% confidence interval: 2.86, 6.95) in neurologic emergency department visits; elevation in SO 2 level (per 7.98 μg/m 3 ) was linked to a 5.19% (95% confidence interval: 2.03, 8.44) increase in circulatory emergency department visits. Most positive links were seen during the cold season. Conclusions The results of this study contribute to the evidence of the significant associations between SO 2 and specific neurologic and circulatory conditions, and also provide insight into the planning of clinical services and emergency contingency response for air pollution exposures in Guangzhou.

Background At present, there are few studies on the effect of short-term interactions between ambient air pollutants and temperature on cause-specific emergency department visits in China. This study aimed to explore their short-term interactions on cause-specific emergency department visits using data collected from a total of 65 public hospitals in Guangzhou city, south China. Material and methods We included a total of 226,443 emergency department visits which were diagnosed as neurological, respiratory and circulatory disease in Guangzhou from January 1, 2014 to December 31, 2017. Average daily concentrations of air pollutants including carbon monoxide (CO), particulate matter having a median diameter of 2.5 μm or less (PM2.5), sulfur dioxide (SO2), nitrogen dioxide (NO2) and ozone (O3) were collected from the Guangzhou Environmental Protection Bureau. We employed quasi-Poisson varying coefficient regression models to assess the interaction effects between air pollutants and daily temperature levels (DTLs) on emergency department visits for neurological, respiratory and circulatory diseases, respectively. Results Average number of emergency department visits for neurological, respiratory and circulatory diseases were 92, 26 and 38, respectively. After controlling for other pollutants, meteorological factors and other time-varying confounders, we found the interactions between NO2 and the 1st DTL (3.4–17.1 °C), NO2 and the 2nd DTL (17.1–23.5 °C) for neurological emergency department visits were statistically significant, displaying a nonlinear relationship. Additionally, we found that the interactions between SO2 and the 4th DTL (27.4–31.1 °C) also had a significantly adverse effect on respiratory emergency department visits. Conclusions Our findings provide novel evidence on SO2-by-temperature interactions, and NO2-by-temperature interactions for emergency department visits of cause-specific diseases.

Although ambient air pollution has been consistently associated with morbidity and mortality of stroke, there is limited evidence on whether the control of air pollution would associate with a reduced risk of stroke. The citywide air pollution controlling measures during the 2010 Asian Games in Guangzhou provided such an opportunity to answer this question. We collected daily data on the concentrations of air pollutants and mortality from ischemic and hemorrhagic stroke, and compared them for 51 intervention days in 2010 with the corresponding days in 2006–2009 and 2011 (reference period). Poisson-based interrupted time series analysis was employed to estimate the relative risk (RR) and 95% confidence interval (CI). The daily mean concentrations of PM10 (particles with an aerodynamic diameter smaller than 10 μm) was 88.64 μg/m3 during the reference period, and 80.47 μg/m3 during the intervention period. Daily mortality number of total stroke, ischemic and hemorrhagic stroke decreased from 3.67, 2.00 and 1.67 during the reference period, to 3.00, 1.76 and 1.24 during the intervention period; the corresponding RR was 0.79 (95% CI: 0.66–0.94), 0.87 (95% CI: 0.69–1.11) and 0.69 (95% CI: 0.52–0.91), respectively. Our findings show that ambient air pollution controlling measures during the 2010 Asian Games in Guangzhou were associated with a decreased risk of stroke mortality, which suggests a need to reduce air pollution to improve public health.

Background The annual differences in the seasonal influenza vaccine and the circulating strains make it necessary to assess influenza vaccine effectiveness (VE) yearly. We assessed the effectiveness of the trivalent inactivated influenza vaccine for the 2010–2011 and 2011–2012 influenza seasons among children in Guangzhou, China. Methods We conducted a 1:2 matched case–control study based on date of birth (±7 days), gender, and area of residence. The influenza cases from surveillance sites in Guangzhou were laboratory-confirmed during the 2010–2012 seasons. The controls were randomly selected from children aged 6–59 months in the Children's Expanded Programmed Immunization Administrative Computerized System. The influenza vaccination information for both cases and controls was retrieved from this system. Results We analyzed the vaccination information for 1255 influenza cases and 2510 matched controls in 2 influenza seasons in Guangzhou, China. We found that the VE for vaccination during the 2010–2011 and 2011–2012 seasons of virus circulation was 73·2% (95% confidence interval (CI), 52·2–85·0%) and 52·9% (95% CI, 42·1–61·7%), respectively. The VE decreased from 68·9% (95% CI, 57·5–77·2%) in the period between January and March to 48·4% (95% CI, 33·8–59·7%) in the period between April and June. Conclusions This post-licensing study of VE found moderate protection against influenza for vaccinated children aged 6–59 months. Although the influenza vaccine strains for the 2010–2011 and the 2011–2012 seasons were the same, our study indicated that annual vaccination is recommended even for those who received the vaccine during the previous season.

Influenza vaccine has to be reformulated each year due to the ever-changing antigenicity of the influenza virus. However, few post-licensure studies of influenza vaccine are available in China. We aimed to measure the effectiveness of seasonal influenza vaccine during 2 consecutive seasons. Among children in Guangzhou aged 6 to 59 mo in 2010-2012, we matched each child with clinically diagnosed influenza to 3 healthy children. Cases with clinically diagnosed influenza were identified from surveillance system. Healthy controls were randomly sampled from the Children's Expanded Programmed Immunization Administrative Computerized System. Conditional logistic regression was used to calculate vaccine effectiveness (VE). A total of 275 matched sets of subjects were included. VE levels against clinically diagnosed influenza for both seasons combined was 47.4% [95% confidence interval (CI), 8.5-69.8%] for full vaccination for children aged 6-35 mo, 33.6% (95% CI, 5.4-53.5%) for any vaccination for children aged 6-59 mo, respectively. VE by time since vaccination for any vaccination was 34.6% (95% CI, 4.7-55.2%) in 0-5 mo, and no protection was observed in 6-11 mo. Annual, full and timely vaccination should be encouraged for children.