Reducing air pollution could also benefit from agricultural yields

An American study reveals that nitrogen oxides, particularly widespread air pollutants, harm agricultural yields.

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We already knew their harmful effects on human health, we are now able to estimate their consequences on agricultural yields. A study by the University of Stanford (California) and published on Wednesday 1 in Science Advances shows that nitrogen oxides – in particular dioxide and nitrogen monoxide – strongly affect the agricultural productivity. The reduction in this pollution could result in an increase of 6 % to 25 % of yields worldwide.

Nitrogen oxides, or NOX (nitrogen oxides in English), are among the most widespread air pollutants in the world. In 2020, their emissions were estimated at 651,000 tonnes only for France, 56 % of which are allocated to road transport. Industrial activities also contribute to the production of this pollutant, during high heat combustions. Exposure to these pollutants can cause health problems, especially respiratory. On the environmental level, the oxidation of nitrogen monoxide also contributes to the phenomenon of acid rain.

But so far, few studies had been carried out on the consequences of exposure to nitrogen oxides on the yield of crops. Air quality data remains rare in agricultural areas. Only a few observations in clinical conditions had been made and already supposed a negative effect of the NOx on cultures. As part of this study, new satellite data made it possible to study, for the first time in real conditions, the relationship between agricultural yields and exposure to nitrogen oxides. A “persistent negative correlation between nitrogen dioxide and the size of the cultures observed” was thus highlighted. Five geographic areas have been studied: Western Europe, the United States, South America, China and India.

Ozone formation, interaction with other elements

As for humans, nitrogen oxides are particularly toxic chemical compounds for plants. “Exposure to nitrogen oxides can thus cause crop deteriorations on the chemical level,” explains Jennifer Burney, one of the researchers from the University of Stanford, who participated in the study. But the effect of nitrogen oxides on agricultural yields can also be indirect.

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