Recent studies have shown that black carbon, a component of particulate matter (PM), is the second most powerful climate warming pollutant after carbon dioxide (CO2), and international experts have linked it to cancer and other serious health problems. In Latin America, the expanding use of diesel fuels and vehicles, coupled with the incredibly high rates of urbanization, mean that more people are being exposed to pollution that harms their health and environment. While scientists and experts generally know that black carbon has negative impacts on climate, environment and public health, more focused research needs to be done to better understand those impacts in Latin American countries. Policy efforts to reduce diesel emissions -- which have been highly effective in other countries around the world should -- be an important component of any comprehensive strategy to combat climate change and protect public health in Latin America.