 Surface mining operations vary in many ways. In the United States, more than 130,000 miners work in the coal and metal non-metal surface mining industry. One common goal is to keep these miners healthy and safe. One area of concern is the equipment operator's dust levels inside enclosed cabs. According to federal dust records, mobile equipment operators have the highest fireable dust exposure levels of all workers at these mine sites. The National Institute for Occupational Safety and Health has been studying enclosed cabs to determine cost-effective methods for lowering equipment operator's dust levels. This research has shown that there are two key components necessary for an enclosed cab to be effective for dust control protection. The cab must have structural integrity and a good dust filtration system. A good dust filtration system takes outside air, filters it and then delivers this clean air to the inside of the cab. The air is then recirculated in the cab through another filter, always keeping the operator in clean air. In an effort to minimize dust concentrations, the inlet for outside air should be located as far away from the equipment's dust source as possible. This also minimizes dust loading on the system's filtration system. It is also important that the heater and air conditioning discharge be located high in the cab directed down over the equipment operator. Also, the recirculation inlet should be located near the floor of the cab. Structural integrity of the cab is needed to maintain positive air pressure inside the cab, so outside dust air does not leak into the operator's compartment. A field study on an enclosed cab with an older drill rig showed that the cab's structural integrity is a very important component for effective dust control. Even though a new air filtration system was installed, positive cab pressure is not achieved because of the floor fitting door and large holes with drill controls entered the cab. Dust measurements taken before and after the installation of a new system reveal only minor changes to the drill operator's dust exposure. Cab integrity is reduced by having holes, cracks and gaps around windows, doors and controls, and a way to address these problems is by using silicon caulk and rubber gaskets to seal these areas. The interior of the cab should be monitored with a pressure gauge, making sure the positive pressure is always maintained. Low cab pressure will help keep the dust out of the cab in calm conditions. Higher cab pressures will help keep dust out of the cab in windier conditions. If only a minimal amount of positive pressure is attained in the cab, the system can work very effectively. During the installation of a new air filtration system on a front-end loader, time was spent sealing small gaps in the cab and around the doors. As a result, a small amount of positive pressure was achieved and the operator's dust exposure was reduced by 90%. Similar studies performed on other equipment with better cab integrity resulted in higher cab pressures and even greater reductions to the operator's dust exposure. The air filtration system must be in good condition and properly maintained to ensure that clean air is being delivered to the equipment operator. The system should be inspected daily so that any observed problems can be quickly corrected. Builders should be checked for damage and cleaned or replaced as specified by the manufacturers. The cab structure should also be visually inspected, checking for holes or damage, and the inside cab air pressure should be regularly monitored. The work that NIAS has done with us in reducing dust exposures in our drill cabs and mobile equipment cabs has been very beneficial. We've seen significant reductions in our employee exposures. The employees have appreciated that. It has been well received by them. As we all know, the health and safety of our employees is paramount in our industry. Although this research was directed towards mining, it can be applied to agriculture, construction, or any other industries which use enclosed cabs. Enclosed cabs can offer equipment operator's protection for many hazards. Installing and maintaining a good dust filtration system and keeping positive air pressure inside a structurally sound cab provides a cleaner and healthier environment for equipment operators. Thank you.