Air Quality Is Key to Healthy Harvests

The quality of the air we breathe plays a central role in our health, longevity and quality of life. New research indicates it can have a dramatic impact on the food we eat, as well.

A team of Stanford researchers has proven a strong link between nitrogen oxides and crop yields. The findings, published last month in the journal Science Advances, established that this common pollutant targets crop cells while boosting the production of ozone in the atmosphere. In turn, ozone reduces the amount of sunlight crops in the field receive.

Vehicles and factories are the main sources of nitrogen oxide pollution. For the first time, the researchers were able to use advanced satellite imagery to measure nitrogen oxide concentrations across the globe. The data were compared with information about crop yields in agricultural regions worldwide.

According to the study’s authors, “The effects of NO2 estimated in this study represent the net impact of myriad complex processes that govern both atmospheric chemistry (e.g., the conversion of NO2 to other pollutants) and plant biology (e.g., the ability of plants to recover from exposure to high levels of NO2 or O3).”

The Stanford News Service reported: “Based on their observations, the researchers estimated that reducing NOx emissions by about half in each region would improve yields by about 25% for winter crops and 15% for summer crops in China, nearly 10% for both winter and summer crops in Western Europe, and roughly 8% for summer crops and 6% for winter crops in India. North and South America generally had the lowest NOx exposures. Overall, the effects seemed most negative in seasons and locations where NOx likely drives ozone formation.”

Previous research has highlighted the many negative effects of excess ozone in the atmosphere. Approximately 20 percent of the increase in U.S. corn and soybean production since the start of the century can be directly attributed to a reduction in ozone levels over the period, according to one study.

In addition to boosting ozone, nitrogen oxides interact with ammonia, which often is present in the atmosphere in agricultural areas where nitrogenous fertilizers are widely used. This interaction “can result in increased concentrations of ammonium nitrate aerosols and can also oxidize sulfur dioxide and drive formation of ammonium sulfate aerosols,” according to the Stanford team.

“These particles reflect and scatter incoming sunlight, changing the radiation environment experienced by crops and reducing access to photosynthetically active radiation.”

The Stanford study includes a call to action: “Improvements in agricultural productivity are needed in the coming decades to achieve many sustainable development goals, including reduced hunger and increased protection of forest area and biodiversity. Among the many strategies to achieve these gains are efforts to improve air quality. Although these efforts are primarily motivated by human health benefits, the potential agricultural effects are substantial. … A better understanding of the agricultural impacts of air pollution would help to better assess both the potential benefits of air quality improvements and how prominent a role pollution reduction should have among efforts to raise agricultural productivity.”