Ground-level ozone is cutting wheat yields and harming people's health in India, a new UNDP policy brief says.

The brief is called The Overlooked Pollutant. It brings together evidence on heat, health and crop losses.

In Indo-Gangetic Plain districts studied for 2019 to 2021, ozone cut wheat yields by an estimated 9 to 13%.

That is a loss of 3.4 million tonnes, worth nearly one billion US dollars. The figure covers those districts, not all of India.

Ozone gets into plant leaves and weakens photosynthesis, so the crop grows less and gives smaller yields.

For people, it inflames the airways, worsens asthma and can lead to chronic obstructive pulmonary disease.

An analysis of 188 heatwaves found ozone at 85 to 110 micrograms per cubic metre in north India. The WHO guideline is 60.

In summer 2025, a CSE report found high ozone in all of India's mega cities, including Mumbai, Bengaluru and Chennai.

Ozone forms when nitrogen oxides and volatile organic compounds react in sunlight. India's nitrogen oxide emissions have tripled since the 1980s.

An IIT Kharagpur study warns wheat yields could fall as much as 20% after 2050 under high emissions.

The brief calls for cutting nitrogen oxides, volatile organic compounds and methane, the gases that create ozone.

Read the full story on ozone and India's wheat on Trends News Stories.

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