Background Small-area health inequalities may originate from differentials in the spatial distribution of environmental stressors on health. The role played by neighbourhood social mechanisms on small-area health inequalities is difficult to evaluate. We demonstrate that agent-based modelling (ABM) is a useful technique to overcome existing limitations. It allows testing hypotheses that social contagion has the potential to modify the effects of environmental stressors by reducing or increasing small-area health inequalities.

Methods Parameters defining the strength of the effect of social contagion on health behaviour were used together with a stochastic model to obtain for every year the health outcome of every agent based on health the previous year, environmental stressors and health behaviour. Unequal spatial distribution of stressors was operationalised with spatial correlation structure. We measured changes in health inequalities using parameters of the spatial correlation structure of health after 10 years. In a further round of simulations, social contagion depended on the environmental stressors.

Results A social contagion mechanism led to a reduction of small-area health inequalities together with an increase in the spatial reach of the effect of environmental stressors. An association between environmental stressor and social contagion mechanism led to a stronger localisation of the effect of environmental stressors.

Conclusions Hypotheses about the role of neighbourhood social mechanisms can be tested using ABM. The respective models provide a better understanding of mechanisms in the causal chain between environmental stressors and health inequalities. This can pave the way to the development of a new type of neighbourhood-based intervention informed by social mechanisms.