COMPARISON OF LABORATORY CONTAMINATION THROUGH OPEN AND CLOSED DOORS IN A MODEL SYSTEM

Abstract

The results of this research demonstrate that with corridors at a higher air pressure than adjoining rooms, rooms with open doors receive greater contamination than rooms with closed doors. Examination of the data by an analysis of variance (ANOVA), employing a significance level of 0.05, yielded a P value of 4.9 x 10­­­­­¯¹² for the effect of door condition. The average contamination level for test rooms with open doors was four times greater than that for test rooms with closed doors. Diffusion and local air turbulence in the corridor are probably responsible for the greater contamination of rooms with open doors. With doors closed, increasing the pressure differential significantly increased test room contamination. The closed door P value for the effect of pressure differential was 7.3 x 10­­­­­¯⁹. When room doors were closed, increasing the pressure differential from 0.005 to 0.02 inches of water doubled the average test room contamination. With doors open, the pressure differential had much less significance than with doors closed. The open door P value for the effect of pressure differential was 0.046. Location of test rooms, relative to source room, affected their contamination levels in both open and closed door experiments. This occurred because the swing of the source room door resulted in a directional distribution of tracer which affected the rooms differently.