The size of the groups (50 each) was determined from a preliminary study at a 95% confidence interval (80% power, variance of 6) with a clinically-acceptable rate difference of 3 and replacements in the formula of averages for comparison. To prevent duplicate samples and unwanted effects of geranium essential oil on the control group, only one type of intervention was applied to any one patient (geranium essence or placebo) during a single work shift in a single day. Similar envelopes used for both treatment groups to randomise allocation during each work shift. Pelargonium graveolens, is a rose-scented species of the genus Geranium.