"Respirable silica dust exposure has long been known to be a serious health threat to workers in many industries. Overexposure to respirable silica dust can lead to the development of silicosis - a lung disease that can be disabling and fatal in its most severe form. Once contracted, there is no cure for silicosis so the goal must be to prevent development by limiting a worker's exposure to respirable silica dust. In addition, the International Agency for Research on Cancer (IARC) has concluded that there is sufficient evidence to classify silica as a human carcinogen. For workers in the metal/nonmetal mining industry, the Mine Safety and Health Administration (MSHA) regulates and monitors exposure to respirable silica dust through personal dust sampling. Recent MSHA personal sampling results indicate that overexposures to respirable silica dust continue to occur for miners in metal/nonmetal mining operations. From 2004 to 2008, the percentages of samples that exceeded the applicable respirable dust standard for the different mining commodities were: 1. 12% for sand and gravel; 2.13% for stone; 3.18% for nonmetal; 4.21% for metal. Of the 2,407 deaths attributed to silicosis in the United States frm 1990-1999, employment information was available for 881 deaths. Metal/nonmetal mining was the industry recorded for over 15% of these 881 deaths, with mining machine operator the most frequently recorded occupation. In light of ongoing silica overexposures and reported silicosis deaths in metal/nonmetal miners, an ongoing threat to miners' health is evident. This handbook was developed to identify available engineering controls that can assist the industry in reducing worker exposure to respirable silica dust. The controls discussed in this handbook range from long-used controls which have developed into industry standards, to newer controls, which are still being optimized. The intent is to identify the "best practices" that are available for controlling respirable dust levels in underground and surface metal/nonmetal mining operations. This handbook provides general information on the control technologies along with extensive references. In some cases, the full reference(s) will need to be accessed to gain in-depth information on the testing or implementation of the control of interest. The handbook is divided into five chapters. Chapter 1 discusses the health effects of exposure to respirable silica dust, while Chapter 2 discusses dust sampling instruments and sampling methods. Chapters 3, 4 and 5 are focused upon dust control technologies for underground mining, mineral processing, and surface mining, respectively. Finally, it must be stressed that after control technologies are implemented, the ultimate success of ongoing protection for workers is dependent upon continued maintenance of these controls. On numerous occasions, National Institute for Occupational Safety and Health (NIOSH) researchers have seen appropriate controls installed, but worker overexposures continued to occur in the absence of proper maintenance of these controls." - NIOSHTIC-2