Unexpected benefits of agricultural greenhouses in mitigating ozone pollution on crop yields in China

Ozone (O₃) is a major photochemical pollutant that harms crops and reduces yields. While its impact on open-field crops is well-documented, research on O₃ levels in agricultural greenhouses is limited. This study provides the first real-time measurements of O₃ concentrations inside and outside a lettuce-growing tunnel greenhouse in Kunming, China, revealing an average indoor/outdoor (I/O) O₃ ratio of 0.55 ± 0.15. We assessed Accumulated Ozone exposure over a Threshold of 40 ppb (AOT40) and relative yield losses (RYLs) for lettuce as an example, estimating the benefits of greenhouse cultivation across China. In ten major greenhouse farming regions, outdoor O₃ levels consistently exceeded the AOT40 threshold, while indoor levels remained mostly below it. Over five lettuce growing seasons (1.5 months each) from March to October, with I/O ratios of 1.0, 0.70, 0.55, and 0.40, AOT40 values were 7.21 ± 2.71, 2.16 ± 1.15, 0.67 ± 0.46, and 0.03 ± 0.05 ppm h, respectively. Corresponding RYLs were −0.08 ± 0.03, −0.02 ± 0.01, −0.01 ± 0.00, and −0.00 ± 0.00. Greenhouses prevented a 6–8 % yield reduction by lowering internal O₃ levels. This mitigation translated into an economic benefit of 4.9–6.5 billion USD, equivalent to 103.2–147.6 USD per person for China's 55 million greenhouse farmers in 2019, or 3.4–4.6 % of annual greenhouse vegetable production benefits, assuming planting lettuce. This single-crop approximation introduced merely 8.3 % ± 0.7 % overestimation versus Monte Carlo simulations with 17-crop combinations (2–16 species). Our findings show that greenhouses significantly reduce O₃-induced crop damage and offer substantial economic advantages. With rising O₃ levels and the rapid growth of facility agriculture globally, this study underscores the importance of adopting greenhouse cultivation practices.