Ground-level ozone can damage rice, wheat and maize as they grow, reducing yields across East Asia. A 2022 regional study estimated substantial losses in China, Japan and South Korea; a separate 2025 analysis found rising ozone exposure and significant estimated yield impacts in China. These are model-based study estimates—not direct counts of grain missing from a particular harvest—and they vary by crop, place, season and method.
What kind of ozone harms crops?
The concern is surface ozone: a pollutant near the ground that crops encounter during the growing season. It is different from the ozone layer high in the atmosphere, which shields Earth from ultraviolet radiation. The studies discussed here estimate crop exposure and yield effects from ground-level ozone.
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What the East Asia study estimated
Feng and colleagues’ 2022 regional assessment combined ozone-elevation experiments conducted in Asia with monitoring at about 3,000 locations in China, Japan and South Korea. It modeled relative yield losses for three staple cereals. For China, the study estimated losses of 33% for wheat, 23% for rice and 9% for maize. It also estimated annual ozone-related crop production losses worth US$63 billion across the crops and countries within its assessment.
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One free scan finds every outdated or missing driver and matches the right update for your exact hardware.Free scan · exact hardware matchThese figures describe the study’s estimated relative impacts, not a measured shortfall in a single year or a guaranteed loss on every farm. The study also found greater estimated relative yield loss in hybrid rice than in inbred rice, illustrating that crop type can affect the result. The authors wrote that the findings “urge us to take mitigation action for O3 emission control and adaptive agronomic measures against the rising surface O3 levels across East Asia.” Feng et al., Nature Food (2022).
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What newer China estimates add
A 2025 China-only analysis used hourly surface-ozone data at 0.1-degree resolution for 2005–2020 and accumulated exposure above a 40-parts-per-billion threshold, a measure known as AOT40. The authors reported that AOT40 rose 10% during 2005–2019, then fell 5.56% in 2020; their analysis associated the latter change with COVID-19 lockdown conditions. They estimated national relative yield impacts of 14.51% ± 0.43% for wheat, 11.10% ± 0.6% for rice and 3.99% ± 0.11% for maize over the analysis.
Those national figures should not be substituted for the 2022 three-country estimates. The studies use different periods, exposure data and methods, and the newer analysis covers China rather than all of East Asia. Liu and colleagues also projected that national relative yield loss could reach 8%–18% by 2050 under a business-as-usual scenario without emission controls. That is a conditional scenario, not a forecast independent of future policy choices. The authors caution that estimates depend on ozone metrics and on how exposure-response relationships are extrapolated across space and time. Liu et al., Journal of Environmental Sciences (2025).
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- Rechargeable & Long-Lasting: As a rechargeable ozone meter, built-in a 2500 mAh high-capacity battery. Once fully charged, this O3 monitor can continuously operate for up to 16 hours. Whether you’re at home or on the go, allowing you to use the ozone detector anytime and anywhere
- Portable w/ Alarm Protection: This ozone gas detector has three alarm modes, including vibration, sound and flashing lights. The alarm limit value for O3 gas air quality is adjustable. It has a rapid response and can effectively alert you to the leak of ozone gas until the gas concentration is at a safe level
- Multi-Function Ozone Monitor: This ozone gas meter can accurately detect gas/ozone while also keeping track of the ambient temperature (℃/℉) and humidity. Feature manual/auto power off optional to save your battery, also it can record up to 1000 pieces of data for easy ozone monitoring
- Convenient to Use: Ozone gas concentration, Maximum O3 meter values, Temp, and humidity on 2.8” bright backlit LCD screen at the same time. Come with a convenient carrying case and back clip design makes it easy to carry and use
Why estimates differ by region and crop
Regional studies show why a single percentage cannot represent every field. In China’s Yangtze River Delta, an analysis using observations from 158 stations and production records from 193 districts and counties for 2014–2019 estimated relative losses of 4.9%–11.4% for rice and 9.4%–19.3% for wheat. These are regional estimates, not figures for all of China or East Asia. Yangtze River Delta study, Environmental Pollution (2020).
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1Repair Windows errors before they cause bigger problems2Scan for outdated or missing drivers - takes under a minute3Clear out junk files and repair common Windows errorsA separate southern China study of 2013–2019 estimated losses of 4.0%–6.6% for double-early rice and 6.3%–11.1% for double-late rice. Its results apply to those rice cycles and that region, rather than to rice production generally. South China rice study, Agriculture (2023).
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- Rechargeable & Long-Lasting: As a rechargeable ozone meter, built-in a 2500 mAh high-capacity battery. Once fully charged, this O3 monitor can continuously operate for up to 16 hours. Whether you’re at home or on the go, allowing you to use the ozone detector anytime and anywhere
- Portable w/ Alarm Protection: This ozone gas detector has three alarm modes, including vibration, sound and flashing lights. The alarm limit value for O3 gas air quality is adjustable. It has a rapid response and can effectively alert you to the leak of ozone gas until the gas concentration is at a safe level
- Multi-Function Ozone Monitor: This ozone gas meter can accurately detect gas/ozone while also keeping track of the ambient temperature (℃/℉) and humidity. Feature manual/auto power off optional to save your battery, also it can record up to 1000 pieces of data for easy ozone monitoring
- Convenient to Use: Ozone gas concentration, Maximum O3 meter values, Temp, and humidity on 2.8” bright backlit LCD screen at the same time. Come with a convenient carrying case and back clip design makes it easy to carry and use
Comparisons depend on several factors:
- Crop and crop type: Wheat, rice and maize respond differently; rice variety and whether it is grown as an early or late season crop can matter.
- Exposure measure and data: Studies may use AOT40 or other ozone measures, and rely on station monitoring, reanalysis data or a combination.
- Response relationship: Estimated yield effects depend on experimental evidence linking ozone exposure to crop response and on how that relationship is applied across locations.
- Place and period: Countrywide estimates, local studies and projections cover different growing conditions and years.
As a result, a relative yield-loss estimate is not the same as a direct measurement of total production lost. Economic valuations and future scenarios are distinct result types and should not be added to or treated as interchangeable with yield percentages.
What is known about Japan and South Korea now?
The 2022 assessment includes China, Japan and South Korea, but the newer 2025 trend analysis covers China alone. The evidence cited here does not establish comparable up-to-date country-specific ozone trends for Japan and South Korea through 2026. An older 2004 analysis projected conditions for 2020 using assumptions available at the time; those projections are not observations of what happened in 2020 and should not be presented as current measurements. 2004 East Asia assessment, Atmospheric Environment.
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What could reduce the risk?
The studies identify ozone precursor-emission control as the broad response relevant to regional exposure, alongside adaptive agronomic measures. The 2025 paper’s account of lower AOT40 in 2020 does not isolate the effect of a particular long-term policy or establish a farm-level treatment. These findings do not demonstrate that a specific seed, chemical or consumer device will prevent the estimated losses.
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