Figure 3. Comparison of the theoretical (and admittedly speculative) impact of low‐ (upper panel) and high‐ (middle panel) agency interventions to modify levels of physical activity (based on the paper of Adams et al. 2016).

The impact of a polypill is also included for comparative purposes (lower panel). The upper panel demonstrates the impact of introducing a central city congestion charge, similar to that introduced in London in 2003. Figures are estimates based on the observation that two‐thirds of trips through the city are made by public transport, walking or cycling (https://theconversation.com/london-congestion-charge-what-worked-what-didnt-what-next-92478). The middle panel reflects the estimated impacts of public health media strategies to modify physical activity levels (a high‐agency public health intervention). The bottom panel illustrates the proposed pathway for adoption and beneficial impact of a polypill strategy. Numbers are for illustrative and comparative purposes and are speculative and not evidence‐based.