Abstract
On January 27, 1988, the Mine Safety and Health Administration published proposed ventilation standards for underground coal mines. Included in this standard was a proposal that would permit, under certain conditions, the use of belt air to ventilate working faces. Because of concerns regarding the impact that belt air use could have on miner health and safety, the Secretary of Labor appointed an Advisory Committee to assess the belt-air issue. This committee began its evaluation in June 1991.(1) One of the issues evaluated by that committee was the impact of belt-air use on dust levels in the face area. The committee concluded that the use of belt air could increase or decrease dust levels; however, the change would not have a significant impact on face-worker dust exposures. The committee further recommended that a designated area with a 1.0 mg/m3 standard be established when belt air is used to ventilate the face. This designated area would be in the belt entry just outside the section tailpiece. Several specific concerns were addressed during the Advisory Committee meetings. These specific concerns included: 1) the effect on intake dust levels when belt air is used at the face; 2) the effect on worker exposure when belt air is used at the face; and, 3) the potential entrainment of dust in the belt entry. The purpose of this article is to review the specific issues related to respirable dust when belt air is used to ventilate the working face, and provide the data used to evaluate the impact of belt air.