Pressure, Performance, and Pollution: How Performance Gaps Shape Air-Quality Governance in China’s Pearl River Delta

China’s environmental governance relies on quantified league tables, but how different performance gaps motivate local action remains unclear. Using a balanced monthly panel covering nine Pearl River Delta cities from January 2019 to December 2024 (648 city‑months), we distinguish historical (vs. a city’s own prior month) and social (vs. peer mean) gaps, each split into positive and negative. Fixed‑effects regressions show asymmetric responses. After a positive historical gap, the next‑month rank worsens (winner's complacency); after a negative historical gap, the rank improves, but the gain fades within one to two months. Positive social gaps are followed by further improvements, whereas negative social gaps do not trigger the expected catch‑up. Lag tests confirm dissipation within two months, consistent with short‑lived “political blue‑sky” effects. Moderation analysis suggests that higher environmental spending amplifies responses to historical gaps, while a larger secondary‑industry share strengthens responses to social gaps. Designing incentives that combine sustained fiscal commitment with differentiated industrial policies may convert short‑term ranking pressure into durable air‑quality gains.