In the US, agricultural exports are big business, accounting, directly and indirectly, for $321 billion in economic output and 929,000 jobs in 2012. Unfortunately, the adverse impacts on human health are correspondingly significant. In particular, fertilizer use and waste generation associated with these exports are major sources of ammonia emissions. Once airborne, these emissions form tiny particles that can cause bronchitis, asthma, and heart attacks. A new study in Environmental Science & Technology compared the health costs from these ammonia emissions to the value generated by the exports and found that costs exceeded value by about $12 billion. If other externalities—eutrophication, loss of biodiversity, and greenhouse gas emissions—were taken into account, the net value of agricultural exports would be even more negative. The article suggests shifting toward less animal protein in diets and adopting more sustainable practices for fertilizer use and management. As the global demand for food increases with rising population and incomes, such changes will be vital to maintaining public health.