Temporal And Spatial Diffusion Characteristics Of PM10 In Different Environments

In order to understand the diffusion characteristics of temporal and spatial concentration of PM10 in the classroom in different environment,in the summer of2015 established the observation points in the College of Arts and science of Beijing Union University,PM10 1m and 5m concentration in the classroom teaching process was monitored by E-BAM-9800 particulate monitor American Met one company,and its variation with time and space the concentration of PM10 in the level of in-depth analysis and research,and established the multivariate linear 1m and 5m PM10 concentration prediction in the classroom model,for further study in the classroom of healthy of teacher and students to chalk Provide theoretical reference for the impact of the main research results:(1)From the sampling time,sampling third hours,regardless of the number of the blackboard is how much,the concentration of PM10 1m and 5m have reached the maximum number of times(clean the blackboard for 1~4,5~7,8~10,1m and 5m,the average concentration of PM10 reached maximum values were 101?g/m3 ?149?g/m3?100?g/m3,74?g/m3?109?g/m3?70?g/m3),therefore,if there is a lesson to the classroom after two classes in the case of the teachers and students health hazards.The maximum sampling fifth hours,1m and 5m the level of PM10 concentration basically recovered to the concentration level of the two when sampling for first hours,and the concentration of the two was very small.From space,average maximum value than 5m at 28% 1m PM10 concentration in the classroom,and the average concentration of the rising rate of 5m 36%,so in front of students in the actual teaching of writing by the chalk dust hazards of inhalable particles is far greater than the back of the students.From the number of clean the blackboard,the blackboard brush 5~7 times,1m,5m at the concentration of respirable particulate matter reached the average maximum value than the other several times to clean the blackboard respectively higher than48?g/m3,35?g/m3,clean the blackboard for the number of from 1 to 4,1m,5m at the concentration of PM10 reached the maximum value when the average ratio of 8 to 10 times to wipe the blackboard when respectively 1?g/m3,4?g/m3.Therefore,5~7times to wipe the blackboard when the respirable particulate matter harmful to the teachers and students health chalk dust produced,and 8 to 10 times the blackboard eraser minimum.So,writing on the blackboard in quantity of 1 layout of the situation Next,teachers should write the blackboard writing volume of each page of 1/8,1/9 or 1/10,the two section class 8~10 times to wipe the blackboard is appropriate.No matter the blackboard brush 1 times or 10 times,sampling 1~2,1~3 hours in the classroom at 1m of the PM10 concentration rise rate was more than 5m,so on teaching,teachers and students in front of indoor health hazard.(2)From the perspective of the number of erase writing content,writing 3 page volume off,in the classroom the worst air quality,and quantity is 1/2 erase writing on the blackboard in the classroom layout,the best air quality(volume 1/2 page erase blackboard,1m 5m,PM10 reached the maximum concentration ratio when the amount of writing off the 3 suites were low 255?g/m3,221?g/m3),with minimal impact on the health of teachers and students.The concentration of PM10 in the time show,sampling third hours,no matter what is the amount of writing off the page,PM10 and 5m at the concentration of 1m reached the maximum value;sampling 1~2,2~3,1~3,3~4,3~6 hours,the amount of writing on the blackboard erase 1/2~3 pages,in the classroom before the difference the concentration of PM10 increased or decreased rate of increase with the amount of writing on the blackboard and erase.The concentration of PM10 in the space,showing the amount of writing on the blackboard,erase 1/2~3 pages,1m PM10 reached maximum when the ratio of the average concentration of 5m at 14% 1m,at the same time,the concentration of PM10 in samples from 1~2 hours and 1 to 3 hours of rising rates are higher than 5m at 48%,13%.Therefore,the classroom in front of students affected by the chalk dust is greater than the back.(3)No two adjacent effaceurs time interval is 10 min or 30 min,the concentration of PM10 in different times,clean the blackboard 1m and 5m reached the maximum in the sample for third hours,and two adjacent effaceurs time interval is longer,in theclassroom 1m and 5m PM10 concentrations at most large value is small.When the concentration of PM10 and 1m in the teachers at 5m reached the maximum value when the concentration is greater than that of the latter,and when the two adjacent effaceurs time intervals were 10 min,20min,30 min,1m at the PM10 concentration of the average maximum ratio of 5m were 29%,26%,14%.The multiple linear regression model to predict the 1m in the classroom at 5M and PM10 concentration,the higher the concentration of respirable particulate matter two,prediction model of R2 is larger(sampling third hours,1m and 5m PM10 concentration prediction model R2 sampling hours 1,2,4,5,6 were 64%,32%,15%,35%,59%)and the forecasting result is better.