The US Environmental Protection Agency (EPA) began regulating the emissions of greenhouse gases (GHGs) on January 2, 2011. Its long-awaited GHG controls guidance document, PSD and Title V Permitting Guidance for GHGs, was issued on November 10, 2010, and included over 450 pages of guidance and seven sector-specific white papers focused on controlling and reducing the emissions of GHGs through the use of best available control technology (BACT). All new major source permits not issued by January 2, 2011, were potentially impacted. Any new facility emitting more than 100,000 tpy of GHGs comes under scrutiny. Some facilities will have to install new controls, modify their permitting practices, and comply with significant new record-keeping, monitoring and permitting requirements.