U.S. longwall operators find compliance with federal respirable dust regulations difficult to achieve and maintain. Research has found that a major problem on many faces is contamination of the face intake air. Most U.S. longwall faces are currently ventilated from headgate to tailgate. Air is routed up one or more of the headgate entries, through a crosscut, and down the face to a return entry at the tailgate, causing intake air to become contaminated prior to entering the face. Results from this evaluation clearly showed the benefits of homotropal ventilation, as intake dust levels on the face were reduced by over 60% when compared with levels on the majority of longwall faces in the United States.