Reduction in Crop Yield in Mexico Due to Ozone Associated with Emissions from Biomass Burning

In recent decades, tropospheric ozone has become a national air pollution problem that has caused reductions in yield and quality of crops and a generally negative impact on vegetation. Here, we estimate ozone impacts on the production of two vital staple crops (maize and wheat) and consequent economic losses in the growing season (May to August) of 2019 in Mexico resulting from a scenario of the ozone (O₃) produced by total emissions and those formed by the emissions of biomass burning scenario, simulated with the WRF-Chem model. The simulated ozone fields from the WRF-Chem are converted to accumulated ozone above a threshold of 40 ppbv (AOT40) for the crop-growing season in Mexico, and crop yield losses are estimated using maize and wheat specific ozone concentration–response functions based on field studies. Our results show that in 2019, relative yield losses range from 0.1 to 2.4% for maize, and between 0.5 and 40% for wheat, with the losses concentrated in central and northern Mexico. The national maize production losses totaled 545 thousand metric tons and 1100 metric tons for the wheat, valued at 120 million USD and 230 thousand USD. The damage caused by ozone to maize production due to emissions from biomass burning represents only 1% of the national total; however, it reaches up to 8% in Chiapas. This research highlights the need to expand monitoring networks in Mexico to make strategic ozone observations, especially in rural areas, to adopt effective ozone precursor mitigation measures.