Surveys on depressurisation-induced backdrafting and spillage.

Surveys on repressurization-induced backdrafting and spillage were conducted in threedifferent areas of the United States using a common protocol, primarily to assess thecorrespondence between short-term tests and one week of continuous monitoring per house.The short-term tests, under induced conditions, can only indicate whether there is a possibilitythat backdrafting or spillage might occur, whereas real-time monitoring under naturalconditions can give a true indication of backdrafting and spillage events. The commonprotocol used in the surveys included four types of short-term tests and two types ofcontinuous monitoring tests. Sustained backdrafting events were rare during the real-timemonitoring conducted under this study -- this outcome was counter to the short-term testresults, but consistent with results of prior Canadian research. Based on the study data forthree areas in the U. S., short-term tests under induced conditions do not appear to predictreal-life backdrafting events and significantly overstated the likelihood of such occurrences.