The Classroom Environment In Elementary School And Its Association With Airborne Transmission Of Common Cold

The classroom environment is an important part of the indoor environment,the air quality of which strongly affects students’ health and study efficiency.The elementary school students in China spend a long time in classrooms,and the density in classroom is large.What’s more,these students also have immunological deficiency compared to adults.These all make the classroom an important place for the spread of infectious disease.This study focuses on the indoor environment of classrooms in elementary schools and the effect on the spread of common cold.The study was completed in 2 parts:the literature review and the classroom inspections.For the literature review,we read the articles published in 2013-2018,which focused on the indoor environment of Chinese schools,especially the primary schools.This part of study helps us to get a whole image of the indoor environment in schools.The classroom inspections were accomplished in an elementary school in the center part of Tianjin during the November,2018 to June,2019.The objects of our study are the 369 students from the 2nd grade and 5th grade in 10 classrooms.We did 2 kinds of inspections:the short-term test and the long-term monitoring.The short-term tests were finished every season,focusing on PM2.5,PM0.1,HCHO,TVOC,benzene,toluene and xylene;the long-term test not only monitored the concentration of CO₂,temperature,relative humidity and air change rate,but also recorded the absence for common cold.During the work of literature review,we read 147 articles in school indoor environment and 19 in primary schools.The results of the literature review show that the studies mainly focused on the particles,HCHO and CO₂,only the CO₂ concentration exceeded the national standard.In the classroom inspections,the concentration of TVOC,benzene,toluene,xylene,particles and HCHO were all under the national standard;The concentration of CO₂ and the air change rate exceeded much of the standard.Only 13%of the CO₂ results were under the standard of 1000ppm,and none of the ventilation per person results were higher than the national standard.We used the linear mixed model to analysis the relationship between the ventilation,the concentration of CO₂,temperature,relative humidity and the absence rate for common cold.The findings are:（1）The temperature and relative humidity have significant effect on the absence rate for influenza.When the temperature increases 1℃,or the RH increases 1%,the absence rate for common cold will decrease 0.17%and 0.05%separately after adjusted the age.（2）The change of ventilation has significant effects for the absence rate for common cold.After adjusted for the effect of age,temperature and relative humidity,the absence rate decreases 0.45%when the air change rate increases 1 time/hour.We also used the Wells-Riley model to predict the minimum volume of ventilation,which could ensure a healthy environment without a mass outbreak of common cold.After this study,we have a whole image of the indoor environment and students’health in elementary schools,and we studied the relationship between the indoor environment and common cold.This study would support us improve the indoor environment and students’ health.And this work may also help the nation to revise the standard in indoor environment.