Canada: The Memorandum of Understanding (MOU) is a document signed by the Railway Association of Canada, Environment Canada and Transport Canada which sets out measures on a voluntary basis to address CAC and GHG emissions from all railway operations in Canada. The MOU calls for a Locomotive Emissions Monitoring (LEM) report to be published annually containing the respective cumulative data on CAC and GHG emissions, and information related to emissions reduction actions taken by the railways. The previous MOU covered the period 1995 to 2005; the current MOU covers the period 2006 to 2010, as exhibited in Appendix A. Once the MOU expires, the voluntary approach will be replaced with a regulatory regime implemented under the Railway Safety Act to take effect in 2011. USA: The U.S. Environmental Protection Agency (EPA) rulemaking promulgated in 1998 contains three levels of locomotive-specific emissions limits corresponding to the date of a locomotive's original manufacture, that is, Tier 0, Tier 1 and Tier 2 (as listed below). The significance of the U.S. EPA regulations for Canadian railways is that the new locomotives they traditionally acquire from the American locomotive original equipment manufacturers (OEM) are manufactured to meet the latest EPA emissions limits. Hence, emissions in Canada are reduced as these new locomotives are acquired