Locomotives do heavy work - often 24 hours per day, seven days per week - operating in cities near residential areas, schools, hospitals, and other sensitive areas. Although they emit fewer pollutants than trucks carrying the same amount of cargo, locomotives normally use diesel fuel and can emit high levels of air pollutants such as particulate matter (PM), oxides of nitrogen (NOx), and carbon monoxide (CO). To reduce the impact of locomotive emissions on air quality, the US EPA has both regulatory and voluntary programs in place. However, air quality monitors near rail yards in Georgia measured unusually high levels of pollutants, so the Georgia Environmental Protection Division (EPD) implemented a program to understand and reduce emissions from rail yards. Information on the analysis and program is available here.