ABSTRACT
Objective@#To explore the status of PM 2.5 pollution in school classrooms and the student exposure level, and to provide basic data to safeguard the health of students.@*Methods@#This study continuously monitored the PM 2.5 levels of 16 naturally ventilated classrooms in eight primary and secondary schools in Jiamusi for one academic year using an online environmental monitoring instrument. At the same time, outdoor PM 2.5 data was captured for comparative research, and student exposure to PM 2.5 during school hours was evaluated.@*Results@#The average concentration of PM 2.5 in the classroom in the spring and autumn semesters was (26.93±24.7) and (31.85±30.37)μg/m 3, respectively, and the indoor/outdoor ratio ( I/O ) was 0.92 and 0.95, respectively, which indicated a strong correlation between them. The daily average concentration of all classrooms during both semesters was ( 28.93 ±26.85)μg/m 3, which was slightly higher than the average concentration of (27.53±26.53)μg/m 3 during the daytime when students were in school. In addition, the concentration on workdays was higher than that observed on weekends, and this was termed the "weekend effect". The indoor PM 2.5 concentration was lower on higher floors. The comprehensive exposure concentration of students during school was 28.48 μg/m 3 in spring semester and 31.87 μg/m 3 in autumn semester.@*Conclusion@#PM 2.5 levels in the classrooms varied according to time, the horizontal space, and the vertical space, and the level of indoor PM 2.5 pollution largely depended on outdoor pollution sources. Differences in PM 2.5 exposure were observed between.
ABSTRACT
@# Objective To analyze the epidemiological characteristics of mumps in Jiamusi city, and predict the incidence trend, so as to provide evidence for taking targeted prevention and control measures in the cold areas in Heilongjiang Province. Methods The mumps cases were collected from China Information System for Disease Control and Prevention in Jiamusi city from 2004 to 2017.Descriptive epidemiologic method was used for analyzing the epidemic of mumps in Jiamusi city during 2004-2017, and the autoregressive integrated moving average (ARIMA) was used to forecast the incidence of mumps in 2018. Results A total of 1 586 cases of mumps were reported in Jiamusi city during 2004-2017, the average annual incidence rate was 4.52/100 000. The incidence of mumps increased year by year from 2015 to 2017.The ratio of male to female was 1.67 :1,those aged from 3 to 19 years accounted for 86.32% of the total cases, the higher incidence rates were found at the age of 5-9 and 10-14 years.The incidence of mumps presented obviously seasonal characteristics.Most cases concentrated from April to July and from November to January. The incidence of urban disease was higher than that of other counties; The established finally mode was ARIMA(4,1,2)(2,0,0)12 and the predicted incidence from January 2018 to June 2018 was consistent with the actual one.From July 2018 to December 2018,predictive mumps incidence were:0.30/100 000, 0.35/100 000, 0.38/100 000, 0.39/100 000, 0.35/100 000, 0.33/100 000. Conclusions ARIMA model could predict the trend of mumps in Jiamusi city.To reduce the incidence of children, it is recommended to develop a second dose of mumps vaccine at the preschool age(3-6 years)or primary school;At the same time, surveillance and control should be continually strengthened in kindergartens and schools.