Analysis of air samples using the WHO (2007) AGP definitions.

aSample considered positive if aerosol bn unique patients refers to the number of patients these samples were taken from.Column A: Results from univariable logistic regression models examining potential risk factors for production of H1N1 positive aerosol. Sample considered positive if aerosol Column B: Results from univariable negative binomial regression models examining potential risk factors for copy number per litre per minute given H1N1 positive aerosol.A hyphen (-) indicates no positive samples in category. Referent refers to the category of an ordinal or nominal variable against which other categories are compared in the regression model and for which no dummy variable is included in the regression model.