A study has been examining the present problems resulting from inappropriate re-entry times across Australian underground development heading mining practices. It has focused on possible solutions that enable current ventilation practices with reduced quantities of fresh air without affecting re-entry times, or shorter reentry times without increasing fresh air requirements or a combination of both. After blast re-entry times have been identified as a potential safety problems exaggerated by advanced mining technology and complicated by the modern prevalence of 12 hour shifts. Industry surveys on blasting re-entry time indicate most mines rely on a fixed time strategy to deal with the after blast re-entry mostly based on past experiences and observation. Very few monitor blast fumes for gas composition. A series of measurements of after blast fumes in various development heading arrangements has be undertaken to improve the understanding of occurrence and magnitude of blast contaminants. A development face ventilation study has been undertaken. Rigorous analysis has produced two empirical equations that can be used with some confidence to conservatively estimate re-entry times for level development headings. It was concluded that the working space volume used in mathematical modeling might be a constant for development headings of a similar configuration and environment, regardless of the relative distance from the end of the ventilation ducting to the face. Further testing is required to confirm this hypothesis.