Irish Cement in Limerick has been given a warning by the Environmental Protection Agency to improve its environmental performance or "face further sanction".
Four other companies, Tipperary Co-operative Creamery, Rosderra Irish Meats Group in Co Offaly, the Arrow Group in Kildare and T and J Standish in Tipperary have also been included on a priority list.
The EPA said it had launched a new enforcement initiative to drive further environmental compliance at industrial and waste facilities.
Licensed facilities with the poorest compliance status are identified as National Priority Sites for enforcement using a new system developed by the EPA.
The EPA said three of the five sites included on the priority list accounted for "over half of all complaints received to-date in 2017".
Director of the EPA's Office of Environmental Enforcement Gerard O'Leary said "the EPA will escalate enforcement action against companies, and their directors, if necessary, if compliance does not improve".
In May, the Irish Cement plant in Mungret was found to be in non-compliance over dust emissions.