Abstract
A significant public health concern is posed by people’s inadequate comprehension of warning labels on hazardous products, such as potting mix. Inhaling or touching potting mix can lead to the development of Legionnaire’s disease, with the risk increasing with age. With the older population in New Zealand increasing and becoming more involved in gardening behaviours, having expert designed warning labels that conform to human factors principles seems crucial as a step towards preventing negative outcomes. Eight new warning labels were designed in this study for each potting mix and bleach (control) based on the human factors warning guidelines, and recognised comprehension facilitators (e.g., symbols and relevant highlighting), which were compared with existing labels. Participants were 50 younger adults and 50 older adults, who were required to answer comprehension and risk assessment questions about each label. Potting mix and bleach results showed that older adults appeared to perform more accurately than younger adults on relevant and irrelevant highlighting. It was also shown that potting mix warning labels with relevant highlighting were comprehended better than the existing potting mix warning label, contradicting the bleach findings where the existing warning label was more adequately comprehended. It was expected that the relevant highlight warning label would yield more adequate comprehension and risk perception than the existing warning label, but potting mix results were mixed, and bleach results favoured the existing warning label. Symbols on potting mix warnings seemed to aid comprehension for younger but not older adults, and warnings without symbols were better on bleach warning labels. Familiarity had no effect on how participants rated danger in either condition. These results showed that potting mix and bleach warning labels were not directly comparable, suggesting that existing potting mix warning labels may need to undergo changes for viewers to understand them better.