How an Unexpected Asylum Seeker Influx Affects Host Residents’ Mental Health: Quasi-Experimental Evidence from South Korea

The impact of sudden asylum seeker inflows on host residents’ mental health is largely unexplored. The present study addresses this research gap and provides the first causal evidence from the non-Western context by exploiting the unexpected influx of Yemeni asylum seekers to Jeju Island, South Korea. The influx affected the island ‘locally’ due to its region-specific visa-free entry policy and the host government’s immediate restrictions on the asylum seekers’ post-arrival cross-region movement off the island. Such a unique combination of entry policy, post-arrival containment, and geographic separation provides a well-defined quasi-experimental setting for causal investigation. Difference-in-differences estimates based on nationally representative, government-collected data suggest that the influx shock worsened host residents’ mental health outcomes—with higher depression and anxiety and lower life satisfaction. Furthermore, this study provides the evidence on the possible mechanisms linking the influx to hosts’ mental health, revealing heightened public safety worries and diminished trust in government.