Could the World's Overlooked Air Pollutant Trigger a New Crisis in Food Security and Public Health?

A UNDP report warns that ground-level ozone pollution causes nearly 500,000 premature deaths annually, damages crops, threatens food security and accelerates global warming. Stronger pollution controls, cleaner technologies and coordinated climate policies could protect public health, boost agricultural productivity and deliver economic and environmental benefits.

Ground-level ozone is becoming a serious threat to public health, food security, agricultural productivity and climate stability, according to a 2026 policy brief released by the United Nations Development Programme (UNDP). Prepared by UNDP researchers Elisa Puzzolo and Xueer Fei, with scientific review from Johns Hopkins University and the Clean Air Fund, the report draws on evidence from the World Health Organization (WHO), Health Effects Institute, Intergovernmental Panel on Climate Change (IPCC), Copernicus Atmosphere Monitoring Service and International Energy Agency. The report warns that this largely invisible pollutant contributed to nearly 500,000 premature deaths worldwide in 2023 while damaging crops, weakening ecosystems and accelerating global warming.

Unlike the protective ozone layer high in the atmosphere, ground-level ozone forms when pollutants released by vehicles, industries, power plants and agricultural activities react in sunlight. Rising temperatures, rapid urbanization and increasingly frequent wildfires are making the problem worse. The report estimates that tropospheric ozone has contributed approximately 0.23°C to present-day global warming, highlighting its role as both an air pollutant and a greenhouse gas.

Rising Heat Turns Invisible Pollution into a Growing Health Emergency

Extreme heat is making ozone pollution increasingly dangerous. Higher temperatures accelerate the chemical reactions that produce ozone, exposing people to harmful pollution during periods when they are already vulnerable to heat-related illnesses.

Research examining 188 heatwave events in India found that ozone concentrations frequently exceeded WHO guidelines, reaching 85–110 micrograms per cubic metre in northern regions. During Europe's June 2026 heatwave, approximately 300 million people experienced ozone concentrations above the European Union's target value, with some locations recording levels exceeding 190 micrograms per cubic metre.

The health consequences are substantial. Ground-level ozone damages lung tissue, causes respiratory inflammation and increases the likelihood of asthma attacks, breathing difficulties and chronic respiratory illnesses. The report estimates that ozone exposure contributes to 9 million–23 million asthma-related emergency visits annually, representing approximately 8–20 percent of such visits worldwide.

Long-term exposure was associated with around 470,000 deaths from chronic obstructive pulmonary disease in 2023. The attributable health burden has increased by more than 50 percent since 2000. Children, older adults, outdoor workers and people with existing respiratory conditions face particularly high risks.

Billions in Crop Losses Put Farmers and Global Food Security at Risk

Agriculture is among the sectors most vulnerable to ozone pollution. The pollutant enters plant leaves, damages tissues and reduces photosynthesis, weakening crop growth and lowering yields.

Global estimates suggest ozone-related yield losses of 6–16 percent for soybeans, 4–15 percent for wheat, 3–4 percent for rice and 2.5–5.5 percent for maize. In China, losses can reach 33 percent for wheat, 23 percent for rice and 9 percent for maize, contributing to approximately US$63 billion in annual agricultural losses across East Asia.

India's Indo-Gangetic Plain illustrates the economic consequences. Between 2019 and 2021, ozone exposure reduced wheat yields by an estimated 9–13 percent across the districts studied, causing production losses of approximately 3.4 million tonnes valued at nearly US$1 billion.

These losses threaten farmers' incomes, reduce agricultural supplies and can increase food prices for consumers. Smallholder farmers are particularly vulnerable because lower harvests limit their ability to invest in future production.

Research cited by UNDP suggests that reducing ozone pollution alongside climate mitigation could offset approximately 15 percent of the projected increase in global hunger risk by 2050. India and sub-Saharan Africa together account for 56 percent of the estimated global reduction in hunger risk attributable to lower ozone pollution.

Forests, Pollinators and Climate Face an Overlooked Environmental Threat

Ground-level ozone also damages forests and ecosystems that support biodiversity and climate stability. By reducing photosynthesis, ozone weakens vegetation's ability to absorb carbon dioxide and store carbon.

The report estimates that ozone pollution reduces the productivity of Asian tropical forests by approximately 11 percent. In the Amazon, wildfire-related ozone damage reduces carbon uptake by an amount equivalent to approximately 24 percent of the carbon released directly by fires.

Pollinators face another hidden threat. Ozone disrupts the natural scents that insects use to locate flowers, reducing pollination success. This is concerning because approximately 75 percent of crop species and nearly 90 percent of wild flowering plants depend at least partly on animal pollination.

These environmental impacts demonstrate that ozone pollution threatens not only individual ecosystems but also the natural processes supporting food production, biodiversity and climate resilience.

Can Stronger Pollution Controls Deliver Cleaner Air and Economic Gains?

The report highlights lessons from China, Japan, Mexico and the Republic of Korea, showing that reducing ozone requires coordinated action across transport, industry, energy and agriculture.

China's experience demonstrates that reducing nitrogen oxides alone may not control ozone without corresponding reductions in volatile organic compounds. Industrial leak detection programmes reduced volatile organic compound emissions by 42–57 percent in studied Chinese refineries.

Cleaner fuels, stricter vehicle standards, electric mobility and industrial emission controls can reduce ozone-forming pollutants. Methane reduction offers additional benefits. According to the International Energy Agency, existing technologies could reduce methane emissions from the oil and gas sector by approximately 75 percent, with around half of these reductions achievable at no net cost.

UNDP urges governments to integrate ozone mitigation into climate policies, agricultural planning, public health strategies and industrial regulations. Stronger monitoring systems, international cooperation and investment in cleaner technologies are essential.

For policymakers, businesses and development partners, the central message is that tackling ground-level ozone offers benefits beyond cleaner air. Coordinated action could reduce healthcare costs, protect agricultural incomes, improve food security and strengthen climate resilience, delivering measurable economic and environmental gains within years.