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ObjectiveTo determine the epidemic characteristics of anthrax in Chengde City， Hebei Province from 2005 to 2021， and to provide evidence for formulating prevention and control measures of anthrax and reducing incidence rate. MethodsThis study collected the data of anthrax epidemic in Chengde City and conducted descriptive analysis. ResultsFrom 2005 to 2021， a total of 11 anthrax cases were reported in Chengde City with no death. The average incidence rate was 0.08/105， which remained low. Furthermore， 10 cases were cutaneous anthrax and 1 case was pulmonary anthrax. The cases were mainly reported in Weichang County， accounting for 90.91% of the total reported cases， followed by Pingquan City. In addition， the cases were mainly reported from July to August and mainly between 30 and 59 years old with a gender ratio of 2.67∶1. ConclusionThe anthrax epidemic in Chengde City is likely to increase. It mainly occurs in summer， rural areas， and male young and middle-aged farmers. It is necessary to improve epidemic monitoring， health education， disease prevention capacity， early identification of the epidemic， and active response.
RESUMO
In order to study the seasonal variations and pollution sources of carbonaceous species in PM2.5 in Chengde, the concentration of these components was determined in atmospheric PM2.5 samples collected in January, April, July, and October 2019. The change in carbonaceous species were analyzed based on the estimation of the ratio of organic carbon(OC) to elemental carbon(EC), total carbonaceous aerosol(TCA), and secondary organic carbon(SOC). The source of these pollutants was determined by means of the backward trajectory and principal component analysis(PCA). The results showed that the mean mass concentrations of PM2.5, OC, and EC during the sampling period were(31.26±21.39) µg·m-3,(13.27±8.68) µg·m-3, and(2.80±1.95) µg·m-3, respectively. The seasonal variations of PM2.5 were:winter[(47.68±30.37) µg·m-3]>autumn[(28.72±17.12) µg·m-3]>spring[(26.59±15.32) µg·m-3]>summer[(23.17±8.38) µg·m-3], consistent with the trend of total carbon(TC), OC, and EC. The source of OC and EC during winter(R2=0.85) was similar. Based on the ratio of OC/EC, all four seasons were affected by traffic and coal-burning source emissions, and the most affected season by bituminous coal emissions was winter. The average concentration of TCA was(21.38±13.68) µg·m-3, which accounted for 68.39% of PM2.5. The order of secondary conversion rate(SOC/OC) was:spring(54.09%) >autumn(37.64%) >summer(32.91%) >winter(25.43%). The results of the backward trajectory simulation show that the pollutant concentrations carried by air masses are relatively low in spring and summer, and the transport channels of pollutants are southwest in autumn and northwest in winter. The results of the PCA showed that the key to reducing PM2.5 in Chengde is to control emissions from vehicle exhausts, and coal and biomass combustion sources.