Key points

• In the Corn Belt region, noticeable levels of smoke in the air during summer and fall have become commonplace during the past several years.
• Wildfires in the western United States and Canada have become worse in recent years and will almost certainly continue to increase in frequency and intensity.
• The greatest potential impact of wildfire smoke on crop growth and yield comes through the reduction in sunlight that reaches the crop.
• Wildfire smoke contains multiple pollutants that can be harmful to crops, but it’s not clear that smoke increases the ground-level concentration of those compounds enough to have an impact.
• There are multiple mechanisms through which wildfire smoke could cause reductions in crop yields but it’s unlikely that the smoky conditions experienced during the past few years have had a measurable impact in most areas.
• The effects of wildfire smoke on both agricultural and natural ecosystems are likely to be an active area of research in coming years as smoky days become more common.