Objective To study the dynamic air quality of clean ICU so as to provide evidence for hospital infection management in clean ICU.Methods Flat natural sedimentation method,six percussive determination of planktonic bacteria and dust particle counting method were used to get samples at three different time periods,different regions for four consecutive days in 100 000 air clean ICU.Results The counts of 0.5μm,5 μm dust particles at different time ( morning,afternoon,evening) were significantly different( F =78.85,89.94 ;P ＜ 0.01 ) and the monitor results of different regions( single rooms,double rooms,hall) were significantly different( F =20.21,16.17; P ＜ 0.01 ).The number of planktonic bacteria at different time (morning,afternoon,evening) were significant different(F =14.21,P ＜0.01 ),while there was no difference in different regions ( single rooms,double rooms,hall) ( F =0.98,P ＞ 0.05 ).There was significant difference of depositing bacterial counts at different time and regions( F =5.68,17.05,P ＜ 0.01 ) and there was a positively correlation between planktonic bacterial counts and depositing bacterial counts ( r =0.612,P ＜ 0.05 ).Each level of bacterial average counts of six percussive samplers measured was significantly different (F =8.35,P ＜ 0.01 ),with fifth grade most and fourth grade following.Conclusions Air quality of ICU is not good especially when making ward round; Less than 5 μm particles dominant; the counts of planktonic bacteria and depositing bacteria is increasing when dust particles counts increase,and the air quality of single rooms and double rooms is better than that of the hall.

Objective To investigate the effect of employers' respirator and hat wearing method on class 100 000 clean ICU air quality,in order to provide basis for hospital infection management in ICU.Methods For the control group,the first day (d1) and third day (d3),every employer was demanded to wear a respirator and a hat before entering the ICU.For the observation group,the second day (d2) and forth day (d4),employers were demanded not to wear any respirator or hat.During all four days,they must wear respirator and hat before any nursing operation.Air quality was sampled by class 100 000 clean air using flat panel natural settlement method,dust planktonic bacteria method and particle counting method.The amount of dust,plankton bacterium and descending bacteria were monitored for 4 days and compared between two groups.Results The difference of 0.5 μm dust particles in ICU between the control group and the observation group were statistically significant ( F =40.95,P ＜ 0.05 ).As to 5.0 μm dust particles,there was no significant difference between two groups (F =2.86,P ＞ 0.05 ).0.5 μm dust particles in ICU was lower at d1 and d3,and the difference was statistically significant ( F =40.95,P ＜ 0.05).The number of 0.5 μm dust particles had significant difference between different periods of a day:the morning time segmcnt＞ evening ＞ afternoon ( F =80.72,P ＜0.05 ).The number of 0.5 μm dust particles in the observation group was higher than that in the control group,and the difference was statistically significant ( F =68.84,P ＜ 0.05 ).The number of 5.0 μm dust particles had significant difference between different time periods of a day:the morning time segment ＞afternoon ＞ evening ( F =98.17,P ＜ 0.01 ).The number of dust particles at hall was larger than that at single and double rooms (P ＜0.01 ),but the number had no difference between single room and double room.More subsidence bacteria and floatingbacteria was detected during dl and d3 in the control group,and the difference was statistically significant ( P ＜ 0.01 ).Besides,the difference of the number of subsidence bacteria and floating bacteria in ICU between different time periods was also statistically significant ( P ＜ 0.05 ).Conclusions The number of 0.5 μm dust particles in ICU is smaller when workers wear hats and respirators,while the number of 5.0 μm dust particles remains the same.Under the other conditions remain unchanged,the mainly cause of number increase of dusts,planktonic bacteria and sedimentation bacteria in the morning rounds is the increasing number of working staff.ICU staff has no apparent effect on dynamic class 100 000 clean ICU air quality whether they wear respirators or hats.This kind of behavior is not the key management elements in clean ICU environment.