Given the role of physical human proximity and contact in the spread of COVID-19, we build an index measuring the level of physical interaction for different occupations. Our Physical Interaction Index combines occupational work context information from O*NET and work travel information from the 2010 StatsSA Time Use Survey. We merge this with South African labour market data from 2018-2019 to explore the distribution of physical interaction across occupations and sectors shortly before the pandemic. The index provides some empirical evidence about a dimension of transmission risk that could inform how to calibrate the composition of economic sectors being phased back to work over the next few months. This short note introduces the index and provides some initial descriptive results for the South African labour market.