This paper studies how air pollution shapes offline cashless spending in China. Using monthly transactions from 118,698 merchants in 332 cities from 2019 to 2023, we find that higher pollution raises cashless spending. Instrumental variable and regression discontinuity designs confirm a causal effect. The increase comes mainly from more frequent but smaller purchases and greater participation by new customers. Spending also rebalances from postponable durables toward high-frequency, proximity-based categories, while durables respond little. These results uncover a behavioral channel whereby poor air quality shifts the margins and the composition of offline cashless commerce.