The document summarizes Ontario Regulation 419/05 Section 34, which establishes opacity limits and requirements for visible emissions from industrial sources. It outlines the general 20% opacity limit for emissions, as well as exemptions for sources using high-ash fuels or those with approved alternative monitoring plans. Sources are required to notify the Ministry of the Environment of any exceedances of opacity limits. The regulation also establishes opacity limits and reporting requirements during start-up, shutdown, and maintenance activities.